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{{Short description|Pictorial representation of symmetry}}
{{Lie groups |Semi-simple}}

In the [[Mathematics|mathematical]] field of [[Lie theory]], a '''Dynkin diagram''', named for [[Eugene Dynkin]], is a type of [[Graph (discrete mathematics)|graph]] with some edges doubled or tripled (drawn as a double or triple line).  Dynkin diagrams arise in the classification of [[semisimple Lie algebra]]s over [[algebraically closed field]]s, in the classification of [[Weyl group]]s and other [[finite reflection group]]s, and in other contexts.  Various properties of the Dynkin diagram (such as whether it contains multiple edges, or its symmetries) correspond to important features of the associated Lie algebra.

[[File:Finite Dynkin diagrams.svg|thumb|Finite Dynkin diagrams]]
[[File:Affine Dynkin diagrams.png|thumb|Affine (extended) Dynkin diagrams]]

The term "Dynkin diagram" can be ambiguous. In some cases, Dynkin diagrams are assumed to be [[directed graph|directed]], in which case they correspond to [[root system]]s and semi-simple Lie algebras, while in other cases they are assumed to be [[undirected graph|undirected]], in which case they correspond to Weyl groups. In this article, "Dynkin diagram" means ''directed'' Dynkin diagram, and ''undirected'' Dynkin diagrams will be explicitly so named.

== Classification of semisimple Lie algebras ==
{{Further|Semisimple Lie algebra#Classification}}

The fundamental interest in Dynkin diagrams is that they classify [[semisimple Lie algebra]]s over [[algebraically closed field]]s. One classifies such Lie algebras via their [[root system]], which can be represented by a Dynkin diagram. One then classifies Dynkin diagrams according to the constraints they must satisfy, as described below.

Dropping the direction on the graph edges corresponds to replacing a root system by the [[finite reflection group]] it generates, the so-called [[Weyl group]], and thus undirected Dynkin diagrams classify Weyl groups.

They have the following correspondence for the Lie algebras associated to classical groups over the complex numbers:
* <math>A_n</math>: <math>\mathfrak {sl}_{n+1}</math>, the [[special linear Lie algebra]].
* <math>B_n</math>: <math>\mathfrak{so}_{2n+1}</math>, the odd-dimensional [[special orthogonal Lie algebra]].
* <math>C_n</math>: <math>\mathfrak {sp}_{2n}</math>, the [[symplectic Lie algebra]].
* <math>D_n</math>: <math>\mathfrak{so}_{2n}</math>, the even-dimensional [[special orthogonal Lie algebra]] (<math>n>1</math>).
For the exceptional groups, the names for the Lie algebra and the associated Dynkin diagram coincide.

== Related classifications ==

Dynkin diagrams can be interpreted as classifying many distinct, related objects, and the notation "A<sub>''n''</sub>, B<sub>''n''</sub>, ..." is used to refer to ''all'' such interpretations, depending on context; this ambiguity can be confusing.

The central classification is that a simple Lie algebra has a root system, to which is associated an (oriented) Dynkin diagram; all three of these may be referred to as B<sub>''n''</sub>, for instance.

The ''un''oriented Dynkin diagram is a form of [[Coxeter diagram]], and corresponds to the Weyl group, which is the [[finite reflection group]] associated to the root system. Thus B<sub>''n''</sub> may refer to the unoriented diagram (a special kind of Coxeter diagram), the Weyl group (a concrete reflection group), or the abstract Coxeter group.

Although the Weyl group is abstractly isomorphic to the Coxeter group, a specific isomorphism depends on an ordered choice of simple roots. Likewise, while Dynkin diagram notation is standardized, Coxeter diagram and group notation is varied and sometimes agrees with Dynkin diagram notation and sometimes does not.{{cn|date=May 2021}}

Lastly, ''sometimes'' associated objects are referred to by the same notation, though this cannot always be done regularly. Examples include:
* The [[root lattice]] generated by the root system, as in the [[E8 lattice|E<sub>8</sub> lattice]]. This is naturally defined, but not one-to-one – for example, A<sub>2</sub> and G<sub>2</sub> both generate the [[hexagonal lattice]].
* An associated polytope – for example [[Gosset 4 21 polytope|Gosset 4<sub>21</sub> polytope]] may be referred to as "the E<sub>8</sub> polytope", as its vertices are derived from the E<sub>8</sub> root system and it has the E<sub>8</sub> Coxeter group as symmetry group.
* An associated quadratic form or manifold – for example, the [[E8 manifold|E<sub>8</sub> manifold]] has [[Intersection form (4-manifold)|intersection form]] given by the E<sub>8</sub> lattice.
These latter notations are mostly used for objects associated with exceptional diagrams – objects associated to the regular diagrams (A, B, C, D) instead have traditional names.

The index (the ''n'') equals to the number of nodes in the diagram, the number of simple roots in a basis, the dimension of the root lattice and span of the root system, the number of generators of the Coxeter group, and the rank of the Lie algebra. However, ''n'' does not equal the dimension of the defining module (a [[fundamental representation]]) of the Lie algebra – the index on the Dynkin diagram should not be confused with the index on the Lie algebra. For example, <math>B_4</math> corresponds to <math>\mathfrak{so}_{2\cdot 4 + 1} = \mathfrak{so}_9,</math> which naturally acts on 9-dimensional space, but has rank 4 as a Lie algebra.

The [[#Simply laced|simply laced]] Dynkin diagrams, those with no multiple edges (A, D, E) classify many further mathematical objects; see discussion at [[ADE classification]].

=== Example: A<sub>2</sub> ===
[[File:Root system A2.svg|thumb|The <math>A_2</math> root system]]

For example, the symbol <math>A_2</math> may refer to:
* The '''Dynkin diagram''' with 2 connected nodes, {{Dynkin|node|3|node}}, which may also be interpreted as a '''[[Coxeter diagram]]'''.
* The '''[[root system]]''' with 2 simple roots at a <math>2\pi/3</math> (120 degree) angle.
* The '''Lie algebra''' <math>\mathfrak{sl}_{2+1} = \mathfrak{sl}_3</math> of [[rank (Lie algebra)|rank]] 2.
* The '''[[Weyl group]]''' of symmetries of the roots (reflections in the hyperplane orthogonal to the roots), isomorphic to the [[symmetric group]] <math>S_3</math> (of order 6).
* The abstract '''[[Coxeter group]]''', presented by generators and relations, <math>\left\langle r_1,r_2 \mid (r_1)^2=(r_2)^2=(r_ir_j)^3=1\right\rangle.</math>

== Construction from root systems ==

Consider a [[root system]], assumed to be reduced and integral (or "crystallographic"). In many applications, this root system will arise from a [[semisimple Lie algebra]]. Let <math>\Delta</math> be a set of [[Root system#Positive roots and simple roots|positive simple roots]]. We then construct a diagram from <math>\Delta</math> as follows.<ref>{{harvnb|Hall|2015}} Section 8.6</ref> Form a graph with one vertex for each element of <math>\Delta</math>. Then insert edges between each pair of vertices according to the following recipe. If the roots corresponding to the two vertices are orthogonal, there is no edge between the vertices. If the angle between the two roots is 120 degrees, we put one edge between the vertices. If the angle is 135 degrees, we put two edges, and if the angle is 150 degrees, we put three edges. (These four cases exhaust all possible angles between pairs of positive simple roots.<ref>{{harvnb|Hall|2015}} Propositions 8.6 and 8.13</ref>) Finally, if there are any edges between a given pair of vertices, we decorate them with an arrow pointing from the vertex corresponding to the longer root to the vertex corresponding to the shorter one. (The arrow is omitted if the roots have the same length.) Thinking of the arrow as a "greater than" sign makes it clear which way the arrow should go. Dynkin diagrams lead to a [[Root system#Classification of root systems by Dynkin diagrams|classification]] of root systems. The angles and length ratios between roots are [[Root system#Elementary consequences of the root system axioms|related]].<ref>{{harvnb|Hall|2015}} Proposition 8.6</ref> Thus, the edges for non-orthogonal roots may alternatively be described as one edge for a length ratio of 1, two edges for a length ratio of <math>\sqrt{2}</math>, and three edges for a length ratio of <math>\sqrt{3}</math>. (There are no edges when the roots are orthogonal, regardless of the length ratio.)

In the <math>A_2</math> root system, shown at right, the roots labeled <math>\alpha</math> and <math>\beta</math> form a base. Since these two roots are at angle of 120 degrees (with a length ratio of 1), the Dynkin diagram consists of two vertices connected by a single edge: {{Dynkin|node|3|node}}.

== Constraints ==
{{Expand section|date=December 2009}}

Dynkin diagrams must satisfy certain constraints; these are essentially those satisfied by finite [[Coxeter–Dynkin diagram]]s, together with an additional crystallographic constraint.

== Connection with Coxeter diagrams ==
Dynkin diagrams are closely related to [[Coxeter–Dynkin diagram|Coxeter diagrams]] of finite [[Coxeter group]]s, and the terminology is often conflated.<ref group="note">In this section we refer to the general class as "Coxeter diagrams" rather than "Coxeter–Dynkin diagrams" for clarity, as there is great potential for confusion, and for concision.</ref>

Dynkin diagrams differ from Coxeter diagrams of finite groups in two important respects:
;Partly directed: Dynkin diagrams are ''partly [[directed graph|directed]]'' – any multiple edge (in Coxeter terms, labeled with "4" or above) has a direction (an arrow pointing from one node to the other); thus Dynkin diagrams have ''more'' data than the underlying Coxeter diagram (undirected graph).
:At the level of root systems the direction corresponds to pointing towards the shorter vector; edges labeled "3" have no direction because the corresponding vectors must have equal length. (Caution: Some authors reverse this convention, with the arrow pointing towards the longer vector.)
;Crystallographic restriction: Dynkin diagrams must satisfy an additional restriction, namely that the only allowable edge labels are 2, 3, 4, and 6, a restriction not shared by Coxeter diagrams, so not every Coxeter diagram of a finite group comes from a Dynkin diagram.
:At the level of root systems this corresponds to the [[crystallographic restriction theorem]], as the roots form a lattice.
A further difference, which is only stylistic, is that Dynkin diagrams are conventionally drawn with double or triple edges between nodes (for ''p''&nbsp;=&nbsp;4,&nbsp;6), rather than an edge labeled with "''p''".

The term "Dynkin diagram" at times refers to the ''directed'' graph, at times to the ''undirected'' graph. For precision, in this article "Dynkin diagram" will mean ''directed,'' and the underlying undirected graph will be called an "undirected Dynkin diagram". Then Dynkin diagrams and Coxeter diagrams may be related as follows:
{| class="wikitable" border="1"
! !! crystallographic !! point group
|-
! directed
| Dynkin diagrams
|-
! undirected
| undirected Dynkin diagrams
| Coxeter diagrams of finite groups
|}
By this is meant that Coxeter diagrams of finite groups correspond to [[point group]]s generated by reflections, while Dynkin diagrams must satisfy an additional restriction corresponding to the [[crystallographic restriction theorem]], and that Coxeter diagrams are undirected, while Dynkin diagrams are (partly) directed.

The corresponding mathematical objects classified by the diagrams are:
{| class="wikitable" border="1"
! !! crystallographic !! point group
|-
! directed
| [[root system]]s
|-
! undirected
| [[Weyl group]]s
| [[finite Coxeter group]]s
|}
The blank in the upper right, corresponding to directed graphs with underlying undirected graph any Coxeter diagram (of a finite group), can be defined formally, but is little-discussed, and does not appear to admit a simple interpretation in terms of mathematical objects of interest.

There are natural maps down – from Dynkin diagrams to undirected Dynkin diagrams; respectively, from root systems to the associated Weyl groups – and right – from undirected Dynkin diagrams to Coxeter diagrams; respectively from Weyl groups to finite Coxeter groups.

The down map is onto (by definition) but not one-to-one, as the ''B''<sub>''n''</sub> and ''C''<sub>''n''</sub> diagrams map to the same undirected diagram, with the resulting Coxeter diagram and Weyl group thus sometimes denoted ''BC''<sub>''n''</sub>.

The right map is simply an inclusion – undirected Dynkin diagrams are special cases of Coxeter diagrams, and Weyl groups are special cases of finite Coxeter groups – and is not onto, as not every Coxeter diagram is an undirected Dynkin diagram (the missed diagrams being ''H''<sub>3</sub>, ''H''<sub>4</sub> and ''I''<sub>2</sub>(''p'') for ''p''&nbsp;=&nbsp;5&nbsp;''p''&nbsp;≥&nbsp;7), and correspondingly not every finite Coxeter group is a Weyl group.

==Isomorphisms==
[[File:Dynkin Diagram Isomorphisms.svg|thumb|upright|The [[exceptional isomorphism]]s of connected Dynkin diagrams.]]
Dynkin diagrams are conventionally numbered so that the list is non-redundant: <math>n \geq 1</math> for <math>A_n,</math> <math>n \geq 2</math> for <math>B_n,</math> <math>n \geq 3</math> for <math>C_n,</math> <math>n \geq 4</math> for <math>D_n,</math> and <math>E_n</math> starting at <math>n=6.</math> The families can however be defined for lower ''n,'' yielding [[exceptional isomorphism]]s of diagrams, and corresponding exceptional isomorphisms of Lie algebras and associated Lie groups.

Trivially, one can start the families at <math>n=0</math> or <math>n=1,</math> which are all then isomorphic as there is a unique empty diagram and a unique 1-node diagram. The other isomorphisms of connected Dynkin diagrams are:
* <math>A_1 \cong B_1 \cong C_1</math>
* <math>B_2 \cong C_2</math>
* <math>D_2 \cong A_1 \times A_1</math>
* <math>D_3 \cong A_3</math>
* <math>E_3 \cong A_1 \times A_2</math>
* <math>E_4 \cong A_4</math>
* <math>E_5 \cong D_5</math>

These isomorphisms correspond to isomorphism of simple and semisimple Lie algebras, which also correspond to certain isomorphisms of Lie group forms of these. They also add context to the [[En (Lie algebra)|E<sub>n</sub> family]].<ref>{{citation |title=This Week's Finds in Mathematical Physics (Week 119) |date=April 13, 1998 |first=John |last=Baez |url=http://math.ucr.edu/home/baez/week119.html}}</ref>

== Automorphisms ==
[[File:Dynkin diagram D4.png|thumb|The most symmetric Dynkin diagram is D<sub>4</sub>, which gives rise to [[triality]].]]

In addition to isomorphism between different diagrams, some diagrams also have self-isomorphisms or "[[automorphism]]s". Diagram automorphisms correspond to [[outer automorphism]]s of the Lie algebra, meaning that the outer automorphism group Out = Aut/Inn equals the group of diagram automorphisms.<ref>{{Harvnb |Fulton |Harris |1991 |loc = Proposition D.40}}</ref><ref name="overout">[https://mathoverflow.net/q/14735 Outer automorphisms of simple Lie Algebras]</ref><ref>{{Harvnb |Humphreys |1972 |loc=§ 16.5}}</ref>

The diagrams that have non-trivial automorphisms are A<sub>''n''</sub> (<math>n > 1</math>), D<sub>''n''</sub> (<math>n > 1</math>), and E<sub>6</sub>. In all these cases except for D<sub>4</sub>, there is a single non-trivial automorphism (Out = ''C''<sub>2</sub>, the cyclic group of order 2), while for D<sub>4</sub>, the automorphism group is the [[symmetric group]] on three letters (''S''<sub>3</sub>, order 6) – this phenomenon is known as "[[triality]]". It happens that all these diagram automorphisms can be realized as Euclidean symmetries of how the diagrams are conventionally drawn in the plane, but this is just an artifact of how they are drawn, and not intrinsic structure.

[[File:Dynkin diagram An 2.png|160px|thumb|A<sub>n</sub>.]]
For A<sub>''n''</sub>, the diagram automorphism is reversing the diagram, which is a line. The nodes of the diagram index the [[fundamental weight]]s, which (for A<sub>''n''&minus;1</sub>) are <math>\bigwedge^i C^n</math> for <math>i=1,\dots,n</math>, and the diagram automorphism corresponds to the duality <math>\bigwedge^i C^n \mapsto \bigwedge^{n-i} C^n.</math> Realized as the Lie algebra <math>\mathfrak{sl}_{n+1},</math> the outer automorphism can be expressed as negative transpose, <math>T \mapsto -T^{\mathrm T}</math>, which is how the dual representation acts.<ref name="overout" />

[[File:Dynkin diagram Dn 2.png|160px|thumb|D<sub>n</sub>.]]
For D<sub>''n''</sub>, the diagram automorphism is switching the two nodes at the end of the Y, and corresponds to switching the two [[chirality (mathematics)|chiral]] [[spin representation]]s. Realized as the Lie algebra <math>\mathfrak{so}_{2n},</math> the outer automorphism can be expressed as conjugation by a matrix in O(2''n'') with determinant &minus;1. When ''n'' = 3, one has <math>\mathrm{D}_3 \cong \mathrm{A}_3,</math> so their automorphisms agree, while <math>\mathrm{D}_2 \cong \mathrm{A}_1 \times \mathrm{A}_1</math> is disconnected, and the automorphism corresponds to switching the two nodes.

For D<sub>4</sub>, the [[fundamental representation]] is isomorphic to the two spin representations, and the resulting [[symmetric group]] on three letter (''S''<sub>3</sub>, or alternatively the [[dihedral group]] of order 6, Dih<sub>3</sub>) corresponds both to automorphisms of the Lie algebra and automorphisms of the diagram.

[[File:Dynkin diagram E6 2.png|160px|thumb|E<sub>6</sub>.]]
The automorphism group of E<sub>6</sub> corresponds to reversing the diagram, and can be expressed using [[Jordan algebra]]s.<ref name="overout"/><ref>{{Harvnb |Jacobson |1971 |loc = § 7}}</ref>

Disconnected diagrams, which correspond to ''semi''simple Lie algebras, may have automorphisms from exchanging components of the diagram.

[[File:Dynkin diagram F4 2.png|160px|thumb|In characteristic 2, the arrow on F<sub>4</sub> can be ignored, yielding an additional diagram automorphism and corresponding [[Suzuki–Ree group]]s.]]
In [[positive characteristic]] there are additional "diagram automorphisms" – roughly speaking, in characteristic ''p'' one is sometimes allowed to ignore the arrow on bonds of multiplicity ''p'' in the Dynkin diagram when taking diagram automorphisms. Thus in characteristic 2 there is an order 2 automorphism of <math>\mathrm{B}_2 \cong \mathrm{C}_2</math> and of F<sub>4</sub>, while in characteristic 3 there is an order 2 automorphism of G<sub>2</sub>. But doesn't apply in all circumstances: for example, such automorphisms need not arise as automorphisms of the corresponding algebraic group, but rather on the level of points valued in a finite field.

===Construction of Lie groups via diagram automorphisms===
Diagram automorphisms in turn yield additional [[Lie group]]s and [[groups of Lie type]], which are of central importance in the classification of finite simple groups.

The [[Chevalley group]] construction of Lie groups in terms of their Dynkin diagram does not yield some of the classical groups, namely the unitary groups and the non-[[split orthogonal group]]s. The [[Steinberg group (Lie theory)|Steinberg groups]] construct the unitary groups <sup>2</sup>A<sub>''n''</sub>, while the other orthogonal groups are constructed as <sup>2</sup>D<sub>''n''</sub>, where in both cases this refers to combining a diagram automorphism with a field automorphism. This also yields additional exotic Lie groups <sup>2</sup>E<sub>6</sub> and <sup>3</sup>D<sub>4</sub>, the latter only defined over fields with an order 3 automorphism.

The additional diagram automorphisms in positive characteristic yield the [[Suzuki–Ree group]]s, <sup>2</sup>B<sub>2</sub>, <sup>2</sup>F<sub>4</sub>, and <sup>2</sup>G<sub>2</sub>.

===Folding===
[[File:Geometric folding Dynkin graphs2.png|188px|thumb|Finite Coxeter group foldings.]]
[[File:Geometric folding Dynkin graphs affine2.png|343px|thumb|Affine Coxeter group foldings, with three naming conventions: first, the original extended set; the second used in the context of [[Quiver (mathematics)|quiver]] graphs; and the last by [[Victor Kac]] for [[Affine Lie algebra#Constructing the Dynkin diagrams|twisted affine Lie algebras]].]]
A (simply-laced) Dynkin diagram (finite or [[affine Dynkin diagram|affine]]) that has a symmetry (satisfying one condition, below) can be quotiented by the symmetry, yielding a new, generally multiply laced diagram, with the process called '''folding''' (due to most symmetries being 2-fold). At the level of Lie algebras, this corresponds to taking the invariant subalgebra under the outer automorphism group, and the process can be defined purely with reference to root systems, without using diagrams.<ref>''Algebraic geometry and number theory: in honor of Vladimir Drinfeld's 50th Birthday,'' edited by Victor Ginzburg, [https://books.google.com/books?id=gGUTVxVieRIC&pg=PA47 p. 47, section 3.6: Cluster folding]</ref> Further, every multiply laced diagram (finite or infinite) can be obtained by folding a simply-laced diagram.<ref name="stembridge">[http://www.math.lsa.umich.edu/~jrs/papers/folding.ps.gz Folding by Automorphisms] {{Webarchive|url=https://web.archive.org/web/20160304091644/http://www.math.lsa.umich.edu/~jrs/papers/folding.ps.gz |date=2016-03-04 }}, John Stembridge, 4pp., 79K, 20 August 2008, [http://www.math.lsa.umich.edu/~jrs/other.html Other Articles by John Stembridge]</ref>

The one condition on the automorphism for folding to be possible is that distinct nodes of the graph in the same orbit (under the automorphism) must not be connected by an edge; at the level of root systems, roots in the same orbit must be orthogonal.<ref name="stembridge" /> At the level of diagrams, this is necessary as otherwise the quotient diagram will have a loop, due to identifying two nodes but having an edge between them, and loops are not allowed in Dynkin diagrams.

The nodes and edges of the quotient ("folded") diagram are the orbits of nodes and edges of the original diagram; the edges are single unless two incident edges map to the same edge (notably at nodes of valence greater than 2) – a "branch point" of the map, in which case the weight is the number of incident edges, and the arrow points ''towards'' the node at which they are incident – "the branch point maps to the non-homogeneous point". For example, in D<sub>4</sub> folding to G<sub>2</sub>, the edge in G<sub>2</sub> points from the class of the 3 outer nodes (valence 1), to the class of the central node (valence 3).

The foldings of finite diagrams are:<ref>See {{Harvnb|Stekolshchik|2008|loc=[https://books.google.com/books?id=gtwR-rd4--UC&pg=PA102 p. 102], remark 5.4}} for illustrations of these foldings and references.</ref><ref group="note">Note that Stekloshchik uses an arrow convention opposite to that of this article.</ref>
* <math>A_{2n-1} \to  C_n</math>
:(The automorphism of A<sub>2''n''</sub> does not yield a folding because the middle two nodes are connected by an edge, but in the same orbit.)
* <math>D_{n+1} \to B_n</math>
* <math>D_4 \to G_2</math> (if quotienting by the full group or a 3-cycle, in addition to <math>D_4 \to B_3</math> in 3 different ways, if quotienting by an involution)
* <math>E_6 \to F_4</math>

Similar foldings exist for affine diagrams, including:
* <math>\tilde A_{2n-1} \to \tilde C_n</math>
* <math>\tilde D_{n+1} \to \tilde B_n</math>
* <math>\tilde D_4 \to \tilde G_2</math>
* <math>\tilde E_6 \to \tilde F_4</math>

The notion of foldings can also be applied more generally to [[Coxeter diagram]]s<ref>{{cite book | citeseerx = 10.1.1.54.3122 | chapter = Generalized Dynkin diagrams and root systems and their folding | first = Jean-Bernard | last = Zuber | pages = 28–30 | year = 1998 |editor1=Kashiwara, M. |editor2=Matsuo, A. |editor3=Saito, K. |editor4=Satake, I. |title=Topological Field Theory, Primitive Forms and Related Topics |series=Progress in Mathematics |volume=160 |doi=10.1007/978-1-4612-0705-4_16| isbn = 978-1-4612-6874-1 | s2cid = 12429369 }}</ref> – notably, one can generalize allowable quotients of Dynkin diagrams to H<sub>n</sub> and I<sub>2</sub>(''p''). Geometrically this corresponds to projections of [[uniform polytope]]s. Notably, any simply laced Dynkin diagram can be folded to I<sub>2</sub>(''h''), where ''h'' is the [[Coxeter number]], which corresponds geometrically to projection to the [[Coxeter plane]].

Folding can be applied to reduce questions about (semisimple) Lie algebras to questions about simply-laced ones, together with an automorphism, which may be simpler than treating multiply laced algebras directly; this can be done in constructing the semisimple Lie algebras, for instance. See [https://mathoverflow.net/q/3888 Math Overflow: Folding by Automorphisms] for further discussion.

== Other maps of diagrams ==
{| class=wikitable align=right
|- align=center
|[[File:Root system A2.svg|160px]]<BR>A<sub>2</sub> root system
|[[File:Root system G2.svg|160px]]<BR>G<sub>2</sub> root system
|}

Some additional maps of diagrams have meaningful interpretations, as detailed below. However, not all maps of root systems arise as maps of diagrams.<ref name="armstrong">{{cite web |url=http://unapologetic.wordpress.com/2010/03/05/transformations-of-dynkin-diagrams/ |title=Transformations of Dynkin Diagrams |first1=John |last1=Armstrong |date=March 5, 2010}}</ref>

For example, there are two inclusions of root systems of A<sub>2</sub> in G<sub>2</sub>, either as the six long roots or the six short roots. However, the nodes in the G<sub>2</sub> diagram correspond to one long root and one short root, while the nodes in the A<sub>2</sub> diagram correspond to roots of equal length, and thus this map of root systems cannot be expressed as a map of the diagrams.

Some inclusions of root systems can be expressed as one diagram being an [[induced subgraph]] of another, meaning "a subset of the nodes, with all edges between them". This is because eliminating a node from a Dynkin diagram corresponds to removing a simple root from a root system, which yields a root system of rank one lower. By contrast, removing an edge (or changing the multiplicity of an edge) while leaving the nodes unchanged corresponds to changing the angles between roots, which cannot be done without changing the entire root system. Thus, one can meaningfully remove nodes, but not edges. Removing a node from a connected diagram may yield a connected diagram (simple Lie algebra), if the node is a leaf, or a disconnected diagram (semisimple but not simple Lie algebra), with either two or three components (the latter for D<sub>''n''</sub> and E<sub>''n''</sub>). At the level of Lie algebras, these inclusions correspond to sub-Lie algebras.

The maximal subgraphs are as follows; subgraphs related by a [[#Automorphisms|diagram automorphism]] are labeled "conjugate":
* A<sub>''n''+1</sub>: A<sub>''n''</sub>, in 2 conjugate ways.
* B<sub>''n''+1</sub>: A<sub>''n''</sub>, B<sub>''n''</sub>.
* C<sub>''n''+1</sub>: A<sub>''n''</sub>, C<sub>''n''</sub>.
* D<sub>''n''+1</sub>: A<sub>''n''</sub> (2 conjugate ways), D<sub>''n''</sub>.
* E<sub>''n''+1</sub>: A<sub>''n''</sub>, D<sub>''n''</sub>, E<sub>''n''</sub>.
** For E<sub>6</sub>, two of these coincide: <math>\mathrm{D}_5 \cong \mathrm{E}_5</math> and are conjugate.
* F<sub>4</sub>: B<sub>3</sub>, C<sub>3</sub>.
* G<sub>2</sub>: A<sub>1</sub>, in 2 non-conjugate ways (as a long root or a short root).

Finally, duality of diagrams corresponds to reversing the direction of arrows, if any:<ref name="armstrong" /> B<sub>n</sub> and C<sub>n</sub> are dual, while F<sub>4</sub>, and G<sub>2</sub> are self-dual, as are the simply-laced ADE diagrams.

== Simply laced<!--'Simply laced Dynkin diagram' redirects here--> ==
{{Main|ADE classification}}
[[File:Simply Laced Dynkin Diagrams.svg|thumb|upright|The simply laced Dynkin diagrams classify diverse mathematical objects; this is called the [[ADE classification]].]]

A Dynkin diagram with no multiple edges is called '''simply laced''', as are the corresponding Lie algebra and Lie group. These are the <math>A_n, D_n, E_n</math> diagrams, and phenomena that such diagrams classify are referred to as an [[ADE classification]]. In this case the Dynkin diagrams exactly coincide with Coxeter diagrams, as there are no multiple edges.

== Satake diagrams ==
{{main|Satake diagram}}
{{Expand section|date=December 2009}}

Dynkin diagrams classify ''complex'' semisimple Lie algebras. Real semisimple Lie algebras can be classified as [[Real form (Lie theory)|real forms]] of complex semisimple Lie algebras, and these are classified by [[Satake diagram]]s, which are obtained from the Dynkin diagram by labeling some vertices black (filled), and connecting some other vertices in pairs by arrows, according to certain rules.

== History ==
{{See also|Semisimple Lie algebra#History}}
[[File:Eugene Dynkin.jpg|thumb|upright|[[Eugene Dynkin]].]]

Dynkin diagrams are named for [[Eugene Dynkin]], who used them in two papers (1946, 1947) simplifying the classification of semisimple Lie algebras;<ref name="knapp">{{Harvnb|Knapp |2002 |loc = [https://books.google.com/books?id=U573NrppkA8C&lpg=PA758 p. 758]}}</ref> see {{Harv|Dynkin|2000}}. When Dynkin left the Soviet Union in 1976, which was at the time considered tantamount to treason, Soviet mathematicians were directed to refer to "diagrams of simple roots" rather than use his name.{{Citation needed|date=July 2010}}

Undirected graphs had been used earlier by Coxeter (1934) to classify [[reflection group]]s, where the nodes corresponded to simple reflections; the graphs were then used (with length information) by Witt (1941) in reference to root systems, with the nodes corresponding to simple roots, as they are used today.<ref name="knapp" /><ref name="overdraw">[https://mathoverflow.net/a/20855 Why are the Dynkin diagrams E6, E7 and E8 always drawn the way they are drawn?]</ref> Dynkin then used them in 1946 and 1947, acknowledging Coxeter and Witt in his 1947 paper.

== Conventions ==

Dynkin diagrams have been drawn in a number of ways;<ref name="overdraw" /> the convention followed here is common, with 180° angles on nodes of valence 2, 120° angles on the valence 3 node of D<sub>''n''</sub>, and 90°/90°/180° angles on the valence 3 node of E<sub>''n''</sub>, with multiplicity indicated by 1, 2, or 3 parallel edges, and root length indicated by drawing an arrow on the edge for orientation. Beyond simplicity, a further benefit of this convention is that diagram automorphisms are realized by Euclidean isometries of the diagrams.

Alternative convention include writing a number by the edge to indicate multiplicity (commonly used in Coxeter diagrams), darkening nodes to indicate root length, or using 120° angles on valence 2 nodes to make the nodes more distinct.

There are also conventions about numbering the nodes. The most common modern convention had developed by the 1960s and is illustrated in {{Harv|Bourbaki|1968}}.<ref name="overdraw" />

== Rank 2 Dynkin diagrams ==

Dynkin diagrams are equivalent to generalized [[Cartan matrix|Cartan matrices]], as shown in this table of rank 2 Dynkin diagrams with their corresponding {{math|2{{resx}}2}} Cartan matrices.

For rank 2, the Cartan matrix form is:
: <math>A = \left [\begin{matrix}2&a_{12}\\a_{21}&2\end{matrix}\right ]</math>

A multi-edged diagram corresponds to the nondiagonal Cartan matrix elements {{tmath|-a_{21}, -a_{12} }}, with the number of edges drawn equal to {{tmath|\max(-a_{21}, -a_{12})}}, and an arrow pointing towards nonunity elements.

A '''generalized Cartan matrix''' is a [[square matrix]] <math>A = (a_{ij})</math> such that:
# For diagonal entries, <math>a_{ii} = 2</math>.
# For non-diagonal entries, <math>a_{ij} \leq 0 </math>.
# <math>a_{ij} = 0</math> if and only if <math>a_{ji} = 0</math>

The Cartan matrix determines whether the group is of '''finite type''' (if it is a [[positive-definite matrix]], i.e. all eigenvalues are positive), of '''affine type''' (if it is not positive-definite but positive-semidefinite, i.e. all eigenvalues are non-negative), or of '''indefinite type'''. The indefinite type often is further subdivided, for example a Coxeter group is '''Lorentzian''' if it has one negative eigenvalue and all other eigenvalues are positive. Moreover, multiple sources refer to '''hyberbolic''' Coxeter groups, but there are several non-equivalent definitions for this term. In the discussion below, hyperbolic Coxeter groups are a special case of Lorentzian, satisfying an extra condition. For rank 2, all negative determinant Cartan matrices correspond to hyperbolic Coxeter group. But in general, most negative determinant matrices are neither hyperbolic nor Lorentzian.

Finite branches have <math>(-a_{21}, -a_{12}) = (1,1), (2,1), (3,1)</math>, and affine branches (with a zero determinant) have {{tmath|1=(-a_{21}, -a_{12}) =(2,2)\text{ or }(4,1)}}.

{| class=wikitable width=720
|+ Rank 2 Dynkin diagrams
|-
!rowspan=2|Group<BR>name
!colspan=3|Dynkin diagram
!colspan=2|Cartan matrix
!rowspan=2|Symmetry<BR>order
!rowspan=2|Related<BR>simply-laced<BR>group<sup>3</sup>
|-
!(Standard)<BR>multi-edged<BR>graph<BR>{{Dynkin2|node_n1|3|node_n2}}
!Valued<BR>graph<sup>1</sup>
!Coxeter<BR>graph<sup>2</sup>
!<math>\left [\begin{matrix}2&a_{12}\\a_{21}&2\end{matrix}\right ]</math>
!Determinant<br>{{tmath|(4 - a_{21} \cdot a_{12})}}
|-
! colspan="5" {{rh|align=right}} | [[Dynkin diagram#Finite Dynkin diagrams|Finite]] 
| colspan="3" | Determinant > 0
|- align=center
!A<sub>1</sub>xA<sub>1</sub>
|{{Dynkin|node}} {{Dynkin|node}}
|{{Dynkin|node}} {{Dynkin|node}}
| {{CDD|node|2|node}}
|<math>\left [\begin{smallmatrix}2&0\\0&2\end{smallmatrix}\right ]</math>
|4
|2
|&nbsp;
|- align=center
!A<sub>2</sub><BR>(undirected)
|{{Dynkin|node|3|node}}
|{{Dynkin|node|3|node}}
| {{CDD|node|3|node}}
|<math>\left [\begin{smallmatrix}2&-1\\-1&2\end{smallmatrix}\right ]</math>
|3
|3
|&nbsp;
|- align=center
!B<sub>2</sub>
|{{Dynkin|node|4b|nodeg}}
|{{Dynkin|node|v21|nodeg}}
|
|<math>\left [\begin{smallmatrix}2&-2\\-1&2\end{smallmatrix}\right ]</math>
|2
|4
|<math>{A}_3</math> {{Dynkin|node|branch2}}
|- align=center
!C<sub>2</sub>
|{{Dynkin|nodeg|4a|node}}
|{{Dynkin|nodeg|v12|node}}
|
|<math>\left [\begin{smallmatrix}2&-1\\-2&2\end{smallmatrix}\right ]</math>
|2
|4
|<math>{A}_3</math> {{Dynkin|branch1|node}}
|- align=center
!BC<sub>2</sub><BR>(undirected)
|{{Dynkin|node|4|node}}
|
| {{CDD|node|4|node}}
|<math>\left [\begin{smallmatrix}2&-\sqrt{2}\\-\sqrt{2}&2\end{smallmatrix}\right ]</math>
|2
|4
|
|- align=center
!G<sub>2</sub>
|{{Dynkin|nodeg|6a|node}}
|{{Dynkin|nodeg|v13|node}}
|
|<math>\left [\begin{smallmatrix}2&-1\\-3&2\end{smallmatrix}\right ]</math>
|1
|6
|<math>{D}_4</math> [[File:Dynkin affine D3 folding.png]]
|- align=center
!G<sub>2</sub><BR>(undirected)
|{{Dynkin|node|6|node}}
|
|{{CDD|node|6|node}}
|<math>\left [\begin{smallmatrix}2&-\sqrt{3}\\-\sqrt{3}&2\end{smallmatrix}\right ]</math>
|1
|6
|
|-
! colspan="5" {{rh|align=right}} |[[Dynkin diagram#Affine Dynkin diagrams|Affine]]
| colspan="3" | Determinant = 0
|- align=center
!A<sub>1</sub><sup>(1)</sup>
|{{Dynkin|nodeg|4ab|nodeg}}
|{{Dynkin|nodeg|v22|nodeg}}
| {{CDD|node|infin|node}}
|<math>\left [\begin{smallmatrix}2&-2\\-2&2\end{smallmatrix}\right ]</math>
|0
|∞
|<math>{\tilde{A}}_3</math> [[File:Dynkin affine A3 folding.png]]
|- align=center
!A<sub>2</sub><sup>(2)</sup>
|{{Dynkin|nodeg|4c|node}}
|{{Dynkin|nodeg|v14|node}}
|
|<math>\left [\begin{smallmatrix}2&-1\\-4&2\end{smallmatrix}\right ]</math>
|0
|∞
|<math>{\tilde{D}}_4</math> [[File:Dynkin affine D4 folding.png]]
|-
! colspan="5" {{rh|align=right}}| Hyperbolic 
| colspan="3" | Determinant < 0
|- align=center
!
|colspan=2|{{Dynkin|nodeg|v51|node}}
|
|<math>\left [\begin{smallmatrix}2&-1\\-5&2\end{smallmatrix}\right ]</math>
| &minus;1
| {{n/a}}
|
|- align=center
!
|colspan=2|{{Dynkin|nodeg|v32|nodeg}}
|
|<math>\left [\begin{smallmatrix}2&-2\\-3&2\end{smallmatrix}\right ]</math>
| &minus;2
| {{n/a}}
|
|- align=center
!
|colspan=2|{{Dynkin|nodeg|v61|node}}
|
|<math>\left [\begin{smallmatrix}2&-1\\-6&2\end{smallmatrix}\right ]</math>
| &minus;2
| {{n/a}}
|
|- align=center
!
|colspan=2|{{Dynkin|nodeg|v71|node}}
|
|<math>\left [\begin{smallmatrix}2&-1\\-7&2\end{smallmatrix}\right ]</math>
| &minus;3
| {{n/a}}
|
|- align=center
!
|colspan=2|{{Dynkin|nodeg|v42|nodeg}}
|
|<math>\left [\begin{smallmatrix}2&-2\\-4&2\end{smallmatrix}\right ]</math>
| &minus;4
| {{n/a}}
|
|- align=center
!
|colspan=2|{{Dynkin|nodeg|v81|node}}
|
|<math>\left [\begin{smallmatrix}2&-1\\-8&2\end{smallmatrix}\right ]</math>
| &minus;4
| {{n/a}}
|
|- align=center
!
|colspan=2|{{Dynkin|nodeg|v33|nodeg}}
|
|<math>\left [\begin{smallmatrix}2&-3\\-3&2\end{smallmatrix}\right ]</math>
| &minus;5
| {{n/a}}
|
|- align=center
!
|colspan=2|{{Dynkin|nodeg|vab|nodeg}}
|
|<math>\left [\begin{smallmatrix}2&-b\\-a&2\end{smallmatrix}\right ]</math>
|{{tmath|4-ab<0}}
| {{n/a}}
|
|-
|colspan=8|
Note<sup>1</sup>: For hyperbolic groups, (''a''<sub>12</sub>&sdot;''a''<sub>21</sub>>4), the multiedge style is abandoned in favor of an explicit labeling {{math|(''a''<sub>21</sub>, ''a''<sub>12</sub>)}} on the edge. These are usually not applied to finite and affine graphs.<ref>Section 2.1 in {{cite arXiv |eprint=math/0510216v1|last1=Stekolshchik|first1=Rafael|title=Notes on Coxeter Transformations and the McKay correspondence|year=2005}}</ref>

Note<sup>2</sup>: For undirected groups, [[Coxeter diagram]]s are interchangeable. They are usually labeled by their order of symmetry, with order-3 implied with no label.

Note<sup>3</sup>: Many multi-edged groups can be obtained from a higher ranked simply-laced group by applying a suitable [[Dynkin diagram#Folding|folding operation]].
|}

== Finite Dynkin diagrams ==

{| class="wikitable"
|+ Finite Dynkin graphs with 1 to 9 nodes
|- align=center
!rowspan=2|Rank
!colspan=4|[[Classical Lie group]]s
!colspan=2|[[Exceptional Lie group]]s
|-
!height=35|<math>{A}_{1+}</math>
!<math>{B}_{2+}</math>
!<math>{C}_{2+}</math>
!<math>{D}_{2+}</math>
![[En (Lie algebra)|<math>{E}_{3-8}</math>]]
![[G2 (mathematics)|<math>{G}_{2}</math>]] / [[F4 (mathematics)|<math>{F}_{4}</math>]]
|- align=center
!1
|A<sub>1</sub>&nbsp;<br>{{Dynkin2|node}}
|&nbsp;
|&nbsp;
|&nbsp;
|&nbsp;
|&nbsp;
|- align=center
!2
|A<sub>2</sub>&nbsp;<br>{{Dynkin2|node|3|node}}
|B<sub>2</sub><br>{{Dynkin2|node|4a|node}}
|C<sub>2</sub>=B<sub>2</sub><br>{{Dynkin2|node|4b|node}}
|D<sub>2</sub>=A<sub>1</sub>A<sub>1</sub><br>{{Dynkin2|nodes}}
|&nbsp;
|G<sub>2</sub>&nbsp;<br>{{Dynkin2|node|6a|node}}
|- align=center
!3
|A<sub>3</sub><br>{{Dynkin2|node|3|node|3|node}}
|B<sub>3</sub><br>{{Dynkin2|node|4a|node|3|node}}
|C<sub>3</sub><br>{{Dynkin2|node|4b|node|3|node}}
|D<sub>3</sub>=A<sub>3</sub><br>{{Dynkin|branch1|node}}
|E<sub>3</sub>=A<sub>2</sub>A<sub>1</sub><br>{{Dynkin2|node|3|node|2|node}}
|&nbsp;
|- align=center
!4
|A<sub>4</sub><br>{{Dynkin2|node|3|node|3|node|3|node}}
|B<sub>4</sub><br>{{Dynkin2|node|4a|node|3|node|3|node}}
|C<sub>4</sub><br>{{Dynkin2|node|4b|node|3|node|3|node}}
|D<sub>4</sub><br>{{Dynkin|branch1|node|3|node}}
|E<sub>4</sub>=A<sub>4</sub><br>{{Dynkin2|node|3|node|3|branch}}
|F<sub>4</sub><br>{{Dynkin2|node|3|node|4a|node|3|node}}
|- align=center
!5
|A<sub>5</sub><br>{{Dynkin2|node|3|node|3|node|3|node|3|node}}
|B<sub>5</sub><br>{{Dynkin2|node|4a|node|3|node|3|node|3|node}}
|C<sub>5</sub><br>{{Dynkin2|node|4b|node|3|node|3|node|3|node}}
|D<sub>5</sub><br>{{Dynkin|branch1|node|3|node|3|node}}
|E<sub>5</sub>=D<sub>5</sub><br>{{Dynkin2|node|3|node|3|branch|3|node}}
|- align=center
!6
|A<sub>6</sub>&nbsp;<br>{{Dynkin2|node|3|node|3|node|3|node|3|node|3|node}}
|B<sub>6</sub>&nbsp;<br>{{Dynkin2|node|4a|node|3|node|3|node|3|node|3|node}}
|C<sub>6</sub>&nbsp;<br>{{Dynkin2|node|4b|node|3|node|3|node|3|node|3|node}}
|D<sub>6</sub>&nbsp;<br>{{Dynkin|branch1|node|3|node|3|node|3|node}}
|E<sub>6</sub>&nbsp;<br>{{Dynkin2|node|3|node|3|branch|3|node|3|node}}
|- align=center
!7
|A<sub>7</sub>&nbsp;<br>{{Dynkin2|node|3|node|3|node|3|node|3|node|3|node|3|node}}
|B<sub>7</sub>&nbsp;<br>{{Dynkin2|node|4a|node|3|node|3|node|3|node|3|node|3|node}}
|C<sub>7</sub>&nbsp;<br>{{Dynkin2|node|4b|node|3|node|3|node|3|node|3|node|3|node}}
|D<sub>7</sub>&nbsp;<br>{{Dynkin|branch1|node|3|node|3|node|3|node|3|node}}
|E<sub>7</sub>&nbsp;<br>{{Dynkin2|node|3|node|3|branch|3|node|3|node|3|node}}
|- align=center
!8
|A<sub>8</sub>&nbsp;<br>{{Dynkin2|node|3|node|3|node|3|node|3|node|3|node|3|node|3|node}}
|B<sub>8</sub>&nbsp;<br>{{Dynkin2|node|4a|node|3|node|3|node|3|node|3|node|3|node|3|node}}
|C<sub>8</sub>&nbsp;<br>{{Dynkin2|node|4b|node|3|node|3|node|3|node|3|node|3|node|3|node}}
|D<sub>8</sub>&nbsp;<br>{{Dynkin|branch1|node|3|node|3|node|3|node|3|node|3|node}}
|E<sub>8</sub>&nbsp;<br>{{Dynkin2|node|3|node|3|branch|3|node|3|node|3|node|3|node}}
|- align=center
!9
|A<sub>9</sub>&nbsp;<br>{{Dynkin2|node|3|node|3|node|3|node|3|node|3|node|3|node|3|node|3|node}}
|B<sub>9</sub>&nbsp;<br>{{Dynkin2|node|4a|node|3|node|3|node|3|node|3|node|3|node|3|node|3|node}}
|C<sub>9</sub>&nbsp;<br>{{Dynkin2|node|4b|node|3|node|3|node|3|node|3|node|3|node|3|node|3|node}}
|D<sub>9</sub>&nbsp;<br>{{Dynkin|branch1|node|3|node|3|node|3|node|3|node|3|node|3|node}}
|- align=center
!10+
|..
|..
|..
|..
|}

== Affine Dynkin diagrams ==
{{Further|Affine root system}}

There are extensions of Dynkin diagrams, namely the '''affine Dynkin diagrams'''; these classify Cartan matrices of [[affine Lie algebra]]s. These are classified in {{Harv|Kac|1994|loc=Chapter 4, [https://books.google.com/books?id=kuEjSb9teJwC&pg=PA47 pp. 47–]}}, specifically listed on {{Harv|Kac|1994|loc=[https://books.google.com/books?id=kuEjSb9teJwC&pg=PA53 pp. 53–55]}}.<!-- TeX code for the diagrams can be found at http://tex.stackexchange.com/questions/5309/how-can-i-replicate-affine-dynkin-diagrams-in-kacs-textbook --> Affine diagrams are denoted as <math>X_l^{(1)}, X_l^{(2)},</math> or <math>X_l^{(3)},</math> where ''X'' is the letter of the corresponding finite diagram, and the exponent depends on which series of affine diagrams they are in. The first of these, <math>X_l^{(1)},</math> are most common, and are called '''extended Dynkin diagrams''' and denoted with a [[tilde]], and also sometimes marked with a '''+''' superscript.<ref>See for example {{cite book |first1=James E. |last1=Humphreys |chapter=48. Fundamental domain § Affine reflection groups |title=Reflection Groups and Coxeter Groups |chapter-url=https://books.google.com/books?id=ODfjmOeNLMUC&pg=PA96 |year=1990 |publisher=Cambridge University Press |isbn=978-0-521-43613-7 |pages=96}}</ref> as in <math>\tilde A_5 = A_5^{(1)} = A_5^{+}</math>. The (2) and (3) series are called '''twisted affine diagrams'''.

See [http://lesha.goder.com/dynkin-diagrams.html Dynkin diagram generator] for diagrams.

{| class=wikitable width=840
|- align=center
|[[File:Affine Dynkin diagrams.png|420px]]<BR>The set of extended affine Dynkin diagrams, with added nodes in green (<math>n\ge 3</math> for <math>B_n</math> and <math>n\ge 4</math> for <math>D_n</math>)
|[[File:Twisted affine Dynkin diagrams.png|320px]]<BR>"Twisted" affine forms are named with (2) or (3) superscripts.<BR>(The subscript ''k'' always counts the number of ''yellow'' nodes in the graph, i.e. the total number of nodes minus 1.)
|}

Here are all of the Dynkin graphs for affine groups up to 10 nodes. Extended Dynkin graphs are given as the ''~'' families, the same as the finite graphs above, with one node added. Other directed-graph variations are given with a superscript value (2) or (3), representing foldings of higher order groups. These are categorized as ''Twisted affine'' diagrams.<ref>{{cite book |author-link=Victor Kac |first1=Victor G. |last1=Kac |chapter=4. A Classification of Generalized Cartan Matrices |title=Infinite-Dimensional Lie Algebras |chapter-url=https://books.google.com/books?id=kuEjSb9teJwC&pg=PA53 |year=1990 |publisher=Cambridge University Press |isbn=978-0-521-46693-6 |pages=53–}}</ref>

{| class="wikitable"
|+ Connected affine Dynkin graphs up to (2 to 10 nodes)<BR>(Grouped as undirected graphs)
!Rank
!<math>{\tilde{A}}_{1+}</math>
!<math>{\tilde{B}}_{3+}</math>
!<math>{\tilde{C}}_{2+}</math>
!<math>{\tilde{D}}_{4+}</math>
! E / F / G
|- align=center valign=top
!2
|<math>{\tilde{A}}_{1}</math> or <math>{A}_{1}^{(1)}</math><br>{{Dynkin|node|4ab|nodeg}}
|rowspan=2|&nbsp;
|<math>{A}_{2}^{(2)}</math>: {{Dynkin|nodeg|4c|node}}
|rowspan=3|&nbsp;
|&nbsp;
|- align=center valign=top
!3
|<math>{\tilde{A}}_{2}</math> or <math>{A}_{2}^{(1)}</math>[http://commons.wikimedia.org/wiki/File:DynkinA2Affine.svg<br>{{Dynkin2|branch|loop2g}}]
|<math>{\tilde{C}}_{2}</math> or <math>{C}_{2}^{(1)}</math>[http://commons.wikimedia.org/wiki/File:DynkinC2Affine.svg<br>{{Dynkin2|nodeg|4b|node|4a|node}}]<br><math>{D}_{5}^{(2)}</math>: {{Dynkin2|nodeg|4a|node|4b|node}}<br><math>{A}_{4}^{(2)}</math>: {{Dynkin2|nodeg|4a|node|4a|node}}
|<math>{\tilde{G}}_{2}</math> or <math>{G}_{2}^{(1)}</math>[http://commons.wikimedia.org/wiki/File:DynkinG2Affine.svg<br>{{Dynkin2|node|6a|node|3|nodeg}}]<br><math>{D}_{4}^{(3)}</math><BR><br>{{Dynkin2|node|6b|node|3|nodeg}}
|- align=center valign=top
!4
|<math>{\tilde{A}}_{3}</math> or <math>{A}_{3}^{(1)}</math>[http://commons.wikimedia.org/wiki/File:DynkinA3Affine.svg<br>{{Dynkin2|loop1|nodes|loop2g}}]
|<math>{\tilde{B}}_{3}</math> or <math>{B}_{3}^{(1)}</math>[http://commons.wikimedia.org/wiki/File:DynkinB3Affine.svg<br>{{Dynkin|branch1yg|node|4b|node}}]<br><math>{A}_{5}^{(2)}</math>: {{Dynkin|branch1yg|node|4a|node}}
|<math>{\tilde{C}}_{3}</math> or <math>{C}_{3}^{(1)}</math>[http://commons.wikimedia.org/wiki/File:DynkinC3Affine.svg<br>{{Dynkin2|nodeg|4b|node|3|node|4a|node}}]<br><math>{D}_{6}^{(2)}</math>: {{Dynkin2|nodeg|4a|node|3|node|4b|node}}<br><math>{A}_{6}^{(2)}</math>: {{Dynkin2|nodeg|4a|node|3|node|4a|node}}
|&nbsp;
|- align=center valign=top
!5
|<math>{\tilde{A}}_{4}</math> or <math>{A}_{4}^{(1)}</math><br>[http://commons.wikimedia.org/wiki/File:DynkinA4Affine.svg<br>{{Dynkin2|branch|3s|nodes|loop2g}}]
|<math>{\tilde{B}}_{4}</math> or <math>{B}_{4}^{(1)}</math>[http://commons.wikimedia.org/wiki/File:DynkinB4Affine.svg<br>{{Dynkin|branch1yg|node|3|node|4b|node}}]<br><math>{A}_{7}^{(2)}</math>: {{Dynkin|branch1yg|node|3|node|4a|node}}
|<math>{\tilde{C}}_{4}</math> or <math>{C}_{4}^{(1)}</math>[http://commons.wikimedia.org/wiki/File:DynkinC4Affine.svg<br>{{Dynkin2|nodeg|4b|node|3|node|3|node|4a|node}}]<br><math>{D}_{7}^{(2)}</math>: {{Dynkin2|nodeg|4a|node|3|node|3|node|4b|node}}<br><math>{A}_{8}^{(2)}</math>: {{Dynkin2|nodeg|4a|node|3|node|3|node|4a|node}}
|<math>{\tilde{D}}_{4}</math> or <math>{D}_{4}^{(1)}</math>[http://commons.wikimedia.org/wiki/File:DynkinD4Affine.svg<br>{{Dynkin|branch1|node|branch2gy}}]
|<math>{\tilde{F}}_{4}</math> or <math>{F}_{4}^{(1)}</math>[http://commons.wikimedia.org/wiki/File:DynkinF42Affine.svg<br>{{Dynkin2|node|3|node|4a|node|3|node|3|nodeg}}]<br><math>{E}_{6}^{(2)}</math><BR><br>{{Dynkin2|node|3|node|4b|node|3|node|3|nodeg}}
|- align=center valign=top
!6
|<math>{\tilde{A}}_{5}</math> or <math>{A}_{5}^{(1)}</math>[http://commons.wikimedia.org/wiki/File:DynkinA5Affine.svg<br>{{Dynkin2|loop1|nodes|3s|nodes|loop2g}}]
|<math>{\tilde{B}}_{5}</math> or <math>{B}_{5}^{(1)}</math>[http://commons.wikimedia.org/wiki/File:DynkinB5Affine.svg<br>{{Dynkin|branch1yg|node|3|node|3|node|4b|node}}]<br><math>{A}_{9}^{(2)}</math>: {{Dynkin|branch1yg|node|3|node|3|node|4a|node}}
|<math>{\tilde{C}}_{5}</math> or <math>{C}_{5}^{(1)}</math>[http://commons.wikimedia.org/wiki/File:DynkinC5Affine.svg<br>{{Dynkin2|nodeg|4b|node|3|node|3|node|3|node|4a|node}}]<br><math>{D}_{8}^{(2)}</math>: {{Dynkin2|nodeg|4a|node|3|node|3|node|3|node|4b|node}}<br><math>{A}_{10}^{(2)}</math>: {{Dynkin2|nodeg|4a|node|3|node|3|node|3|node|4a|node}}
|<math>{\tilde{D}}_{5}</math> or <math>{D}_{5}^{(1)}</math>[http://commons.wikimedia.org/wiki/File:DynkinD5Affine.svg<br>{{Dynkin|branch1|node|3|node|branch2gy}}]
|&nbsp;
|- align=center valign=top
!7
|<math>{\tilde{A}}_{6}</math> or <math>{A}_{6}^{(1)}</math>[http://commons.wikimedia.org/wiki/File:AffineA6.svg<br>{{Dynkin2|branch|3s|nodes|3s|nodes|loop2g}}]
|<math>{\tilde{B}}_{6}</math> or <math>{B}_{6}^{(1)}</math><br>{{Dynkin|branch1yg|node|3|node|3|node|3|node|4b|node}}<br><math>{A}_{11}^{(2)}</math>: {{Dynkin|branch1yg|node|3|node|3|node|3|node|4a|node}}
|<math>{\tilde{C}}_{6}</math> or <math>{C}_{6}^{(1)}</math><br>{{Dynkin2|nodeg|4b|node|3|node|3|node|3|node|3|node|4a|node}}<br><math>{D}_{9}^{(2)}</math>: {{Dynkin2|nodeg|4a|node|3|node|3|node|3|node|3|node|4b|node}}<br><math>{A}_{12}^{(2)}</math>: {{Dynkin2|nodeg|4a|node|3|node|3|node|3|node|3|node|4a|node}}
|<math>{\tilde{D}}_{6}</math> or <math>{D}_{6}^{(1)}</math><br>{{Dynkin|branch1|node|3|node|3|node|branch2gy}}
|<math>{\tilde{E}}_{6}</math> or <math>{E}_{6}^{(1)}</math><br>{{Dynkin|nodes|3s|nodes|loop2|3|node|3|nodeg}}
|- align=center valign=top
!8
|<math>{\tilde{A}}_{7}</math> or <math>{A}_{7}^{(1)}</math>[http://commons.wikimedia.org/wiki/File:AffineA7.svg<br>{{Dynkin2|loop1|nodes|3s|nodes|3s|nodes|loop2g}}]
|<math>{\tilde{B}}_{7}</math> or <math>{B}_{7}^{(1)}</math>[http://commons.wikimedia.org/wiki/File:AffineB7.svg<br>{{Dynkin|branch1yg|node|3|node|3|node|3|node|3|node|4b|node}}]<br><math>{A}_{13}^{(2)}</math>: {{Dynkin|branch1yg|node|3|node|3|node|3|node|3|node|4a|node}}
|<math>{\tilde{C}}_{7}</math> or <math>{C}_{7}^{(1)}</math><br>{{Dynkin2|nodeg|4b|node|3|node|3|node|3|node|3|node|3|node|4a|node}}<br><math>{D}_{10}^{(2)}</math>: {{Dynkin2|nodeg|4a|node|3|node|3|node|3|node|3|node|3|node|4b|node}}<br><math>{A}_{14}^{(2)}</math>: {{Dynkin2|nodeg|4a|node|3|node|3|node|3|node|3|node|3|node|4a|node}}
|<math>{\tilde{D}}_{7}</math> or <math>{D}_{7}^{(1)}</math>[http://commons.wikimedia.org/wiki/File:AffineD7.svg<br>{{Dynkin|branch1|node|3|node|3|node|3|node|branch2gy}}]
|<math>{\tilde{E}}_{7}</math> or <math>{E}_{7}^{(1)}</math><br>{{Dynkin|nodesyg|3s|nodes|3s|nodes|loop2|3|node}}
|- align=center valign=top
!9
|<math>{\tilde{A}}_{8}</math> or <math>{A}_{8}^{(1)}</math>[http://commons.wikimedia.org/wiki/File:AffineA8.svg<br>{{Dynkin2|branch|3s|nodes|3s|nodes|3s|nodes|loop2g}}]
|<math>{\tilde{B}}_{8}</math> or <math>{B}_{8}^{(1)}</math><br>{{Dynkin|branch1yg|node|3|node|3|node|3|node|3|node|3|node|4b|node}}<br><math>{A}_{15}^{(2)}</math>: {{Dynkin|branch1yg|node|3|node|3|node|3|node|3|node|3|node|4a|node}}
|<math>{\tilde{C}}_{8}</math> or <math>{C}_{8}^{(1)}</math><br>{{Dynkin2|nodeg|4b|node|3|node|3|node|3|node|3|node|3|node|3|node|4a|node}}<br><math>{D}_{11}^{(2)}</math>: {{Dynkin2|nodeg|4a|node|3|node|3|node|3|node|3|node|3|node|3|node|4b|node}}<br><math>{A}_{16}^{(2)}</math>: {{Dynkin2|nodeg|4a|node|3|node|3|node|3|node|3|node|3|node|3|node|4a|node}}
|<math>{\tilde{D}}_{8}</math> or <math>{D}_{8}^{(1)}</math><br>{{Dynkin|branch1|node|3|node|3|node|3|node|3|node|branch2gy}}
|<math>{\tilde{E}}_{8}</math> or <math>{E}_{8}^{(1)}</math><br>{{Dynkin2|node|3|node|3|branch|3|node|3|node|3|node|3|node|3|nodeg}}
|- align=center valign=top
!10
|<math>{\tilde{A}}_{9}</math> or <math>{A}_{9}^{(1)}</math>[http://commons.wikimedia.org/wiki/File:AffineA9.svg<br>{{Dynkin2|loop1|nodes|3s|nodes|3s|nodes|3s|nodes|loop2g}}]
|<math>{\tilde{B}}_{9}</math> or <math>{B}_{9}^{(1)}</math><br>{{Dynkin|branch1yg|node|3|node|3|node|3|node|3|node|3|node|3|node|4b|node}}<br><math>{A}_{17}^{(2)}</math>: {{Dynkin|branch1yg|node|3|node|3|node|3|node|3|node|3|node|3|node|4a|node}}
|<math>{\tilde{C}}_{9}</math> or <math>{C}_{9}^{(1)}</math><br>{{Dynkin2|nodeg|4b|node|3|node|3|node|3|node|3|node|3|node|3|node|3|node|4a|node}}<br><math>{D}_{12}^{(2)}</math>: {{Dynkin2|nodeg|4a|node|3|node|3|node|3|node|3|node|3|node|3|node|3|node|4b|node}}<br><math>{A}_{18}^{(2)}</math>: {{Dynkin2|nodeg|4a|node|3|node|3|node|3|node|3|node|3|node|3|node|3|node|4a|node}}
|<math>{\tilde{D}}_{9}</math> or <math>{D}_{9}^{(1)}</math><br>{{Dynkin|branch1|node|3|node|3|node|3|node|3|node|3|node|branch2gy}}
|- align=center valign=top
!11
|...
|...
|...
|...
|}

== Hyperbolic and higher Dynkin diagrams ==

The set of compact and noncompact hyperbolic Dynkin graphs has been enumerated.<ref>{{cite journal |arxiv=1003.0564|bibcode=2010JPhA...43o5209C|title=Classification of hyperbolic Dynkin diagrams, root lengths and Weyl group orbits|last1=Carbone|first1=Lisa|last2=Chung|first2=Sjuvon|last3=Cobbs|first3=Leigh|last4=McRae|first4=Robert|last5=Nandi|first5=Debajyoti|last6=Naqvi|first6=Yusra|last7=Penta|first7=Diego|journal=Journal of Physics A: Mathematical and Theoretical|volume=43|issue=15|pages=155209|year=2010|doi=10.1088/1751-8113/43/15/155209|s2cid=16946456}}</ref> All rank 3 hyperbolic graphs are compact. Compact hyperbolic Dynkin diagrams exist up to rank 5, and noncompact hyperbolic graphs exist up to rank 10.

{| class=wikitable
|+ Summary
|-
!Rank 
!Compact
!Noncompact
!Total
|-
!3
||31||93||123
|-
!4
||3||50||53
|-
!5
||1||21||22
|-
!6
||0||22||22
|-
!7
||0||4||4
|-
!8
||0||5||5
|-
!9
||0||5||5
|-
!10
||0||4||4
|}

===Compact hyperbolic Dynkin diagrams===
{| class=wikitable
|+ Compact hyperbolic graphs
|-
!colspan=2|Rank 3
!Rank 4
!Rank 5
|- valign=top
|Linear graphs
* (6 4 2):
** H<sub>100</sub><sup>(3)</sup>: {{Dynkin|node|4b|node|6b|node}}
** H<sub>101</sub><sup>(3)</sup>: {{Dynkin|node|4b|node|6a|node}}
** H<sub>105</sub><sup>(3)</sup>: {{Dynkin|node|4a|node|6b|node}}
** H<sub>106</sub><sup>(3)</sup>: {{Dynkin|node|4a|node|6a|node}}
* (6 6 2):
** H<sub>114</sub><sup>(3)</sup>: {{Dynkin|node|6a|node|6a|node}}
** H<sub>115</sub><sup>(3)</sup>: {{Dynkin|node|6b|node|6a|node}}
** H<sub>116</sub><sup>(3)</sup>: {{Dynkin|node|6a|node|6b|node}}
| Cyclic graphs
* (4 3 3):  H<sub>1</sub><sup>(3)</sup>: {{Dynkin|branch4al|loop2}}
* (4 4 3): 3 forms...
* (4 4 4): 2 forms...
* (6 3 3): H<sub>3</sub><sup>(3)</sup>: {{Dynkin|branch6|loop2}}
* (6 4 3): 4 forms...
* (6 4 4): 4 forms...
* (6 6 3): 3 forms...
* (6 6 4): 4 forms...
* (6 6 6): 2 forms...
|
* (4 3 3 3):
** H<sub>8</sub><sup>(4)</sup>: {{Dynkin|branch4al|3s|branch}}
** H<sub>13</sub><sup>(4)</sup>: {{Dynkin|branch4al|3s|branch4ar}}
* (4 3 4 3):
** H<sub>14</sub><sup>(4)</sup>: {{Dynkin|branch4al|3s|branch4br}}
|
* (4 3 3 3 3):
** H<sub>7</sub><sup>(5)</sup>: {{Dynkin|branch4al|3s|nodes|loop2}}
|}

===Noncompact (over-extended) forms===
Some notations used in [[theoretical physics]], such as [[M-theory]], use a "+" superscript for extended groups instead of a "~" and this allows higher extensions groups to be defined. 
# '''Extended''' Dynkin diagrams (affine) are given "+" and represent one added node. (Same as "~")
# '''Over-extended''' Dynkin diagrams (hyperbolic) are given "^" or "++" and represent two added nodes.
# '''Very-extended''' Dynkin diagrams with 3 nodes added are given "+++".

{| class=wikitable
|+Some example over-extended (hyperbolic) Dynkin diagrams
|- align=center
!Rank
!height=30|AE{{sub|n}} = A<sub>n-2</sub><sup>(1)^</sup>
!height=30|BE{{sub|n}} = B<sub>n-2</sub><sup>(1)^</sup><br>CE{{sub|n}}
!height=30|C<sub>n-2</sub><sup>(1)^</sup>
!height=30|DE{{sub|n}} = D<sub>n-2</sub><sup>(1)^</sup>
! E / F / G
|- align=center
!3
|AE{{sub|3}}:{{Dynkin|node|4ab|nodeg|3|nodeg}}
|&nbsp;
|&nbsp;
|&nbsp;
|&nbsp;
|- align=center
!4
|AE{{sub|4}}:{{Dynkin|branch|loop2g|3|nodeg}}<BR>{{Dynkin|branch|loop2g|4a|nodeg}}<BR>{{Dynkin|branch|loop2g|4b|nodeg}}<BR>{{Dynkin|branch|loop2g|6a|nodeg}}<BR>{{Dynkin|branch|loop2g|6b|nodeg}}
|&nbsp;
|C<sub>2</sub><sup>(1)^</sup><br>{{Dynkin2|nodeg|3|nodeg|4b|node|4a|node}}<br>A<sub>4</sub><sup>(2)'^</sup><br>{{Dynkin2|nodeg|3|nodeg|4a|node|4a|node}}<br>A<sub>4</sub><sup>(2)^</sup><br>{{Dynkin2|nodeg|3|nodeg|4b|node|4b|node}}<br>D<sub>3</sub><sup>(2)^</sup><br>{{Dynkin2|nodeg|3|nodeg|4a|node|4b|node}}
|rowspan=2|&nbsp;
|G<sub>2</sub><sup>(1)^</sup><br>{{Dynkin2|node|6a|node|3|nodeg|3|nodeg}}<br>D<sub>4</sub><sup>(3)^</sup><br>{{Dynkin2|node|6b|node|3|nodeg|3|nodeg}}
|- align=center
!5
|AE{{sub|5}}:{{Dynkin|loop1|nodes|loop2g|3|nodeg}}<BR>{{Dynkin|loop1|nodes|loop2g|4a|nodeg}}<BR>{{Dynkin|loop1|nodes|loop2g|4b|nodeg}}
|BE{{sub|5}}<br>{{Dynkin2|nodeg|3|nodeg|3|branch|4b|node}}<BR>CE{{sub|5}}<br>{{Dynkin2|nodeg|3|nodeg|3|branch|4a|node}}
|C<sub>3</sub><sup>(1)^</sup><br>{{Dynkin2|nodeg|3|nodeg|4b|node|3|node|4a|node}}<br>A<sub>6</sub><sup>(2)^</sup><br>{{Dynkin2|nodeg|3|nodeg|4a|node|3|node|4a|node}}<br>A<sub>6</sub><sup>(2)'^</sup><br>{{Dynkin2|nodeg|3|nodeg|4b|node|3|node|4b|node}}<br>D<sub>5</sub><sup>(2)^</sup><br>{{Dynkin2|nodeg|3|nodeg|4a|node|3|node|4b|node}}
|
|- align=center
!6
|AE{{sub|6}}<br>{{Dynkin|branch|3s|nodes|loop2g|3|nodeg}}
|BE{{sub|6}}<br>{{Dynkin2|nodeg|3|nodeg|3|branch|3|node|4b|node}}<BR>CE{{sub|6}}<br>{{Dynkin2|nodeg|3|nodeg|3|branch|3|node|4a|node}}
|C<sub>4</sub><sup>(1)^</sup><br>{{Dynkin2|nodeg|3|nodeg|4b|node|3|node|3|node|4a|node}}<br>A<sub>8</sub><sup>(2)^</sup><br>{{Dynkin2|nodeg|3|nodeg|4a|node|3|node|3|node|4a|node}}<br>A<sub>8</sub><sup>(2)'^</sup><br>{{Dynkin2|nodeg|3|nodeg|4b|node|3|node|3|node|4b|node}}<br>D<sub>7</sub><sup>(2)^</sup><br>{{Dynkin2|nodeg|3|nodeg|4a|node|3|node|3|node|4b|node}}
|DE{{sub|6}}<br>{{Dynkin|triplebranch1|node|3|nodeg|3|nodeg}}
|F<sub>4</sub><sup>(1)^</sup><br>{{Dynkin2|node|3|node|4a|node|3|node|3|nodeg|3|nodeg}}<br>E<sub>6</sub><sup>(2)^</sup><br>{{Dynkin2|node|3|node|4b|node|3|node|3|nodeg|3|nodeg}}
|- align=center
!7
|AE{{sub|7}}<br>{{Dynkin|loop1|nodes|3s|nodes|loop2g|3|nodeg}}
|BE{{sub|7}}<br>{{Dynkin2|nodeg|3|nodeg|3|branch|3|node|3|node|4b|node}}<BR>CE{{sub|7}}<br>{{Dynkin2|nodeg|3|nodeg|3|branch|3|node|3|node|4a|node}}
|
|DE{{sub|7}}<br>{{Dynkin2|node|3|branch|3|branch|3|nodeg|3|nodeg}}
|
|- align=center
!8
|AE{{sub|8}}<br>{{Dynkin|branch|3s|nodes|3s|nodes|loop2g|3|nodeg}}
|BE{{sub|8}}<br>{{Dynkin2|nodeg|3|nodeg|3|branch|3|node|3|node|3|node|4b|node}}<BR>CE{{sub|8}}<br>{{Dynkin2|nodeg|3|nodeg|3|branch|3|node|3|node|3|node|4a|node}}
|
|DE{{sub|8}}<br>{{Dynkin2|node|3|branch|3|node|3|branch|3|nodeg|3|nodeg}}
|E<sub>6</sub><sup>(1)^</sup><br>{{Dynkin|nodes|3s|nodes|loop2|3|node|3|nodeg|3|nodeg}}
|- align=center
!9
|AE{{sub|9}}<br>{{Dynkin|loop1|nodes|3s|nodes|3s|nodes|loop2g|3|nodeg}}
|BE{{sub|9}}<br>{{Dynkin2|nodeg|3|nodeg|3|branch|3|node|3|node|3|node|3|node|4b|node}}<BR>CE{{sub|9}}<br>{{Dynkin2|nodeg|3|nodeg|3|branch|3|node|3|node|3|node|3|node|4a|node}}
|
|DE{{sub|9}}<br>{{Dynkin2|node|3|branch|3|node|3|node|3|branch|3|nodeg|3|nodeg}}
|E<sub>7</sub><sup>(1)^</sup><br>{{Dynkin2|nodeg|3|nodeg|3|node|3|node|3|branch|3|node|3|node|3|node}}
|- align=center
!10
|&nbsp;
|BE{{sub|10}}<br>{{Dynkin2|nodeg|3|nodeg|3|branch|3|node|3|node|3|node|3|node|3|node|4b|node}}<BR>CE{{sub|10}}<br>{{Dynkin2|nodeg|3|nodeg|3|branch|3|node|3|node|3|node|3|node|3|node|4a|node}}
|
|DE{{sub|10}}<br>{{Dynkin2|node|3|branch|3|node|3|node|3|node|3|branch|3|nodeg|3|nodeg}}
|E{{sub|10}}=E<sub>8</sub><sup>(1)^</sup><br>{{Dynkin2|node|3|node|3|branch|3|node|3|node|3|node|3|node|3|nodeg|3|nodeg}}
|}

=== 238 Hyperbolic groups (compact and noncompact) ===
The 238 hyperbolic groups (compact and noncompact) of rank <math>n \ge 3</math> are named as <math>H_i^{(n)}</math> and listed as <math>i=1,2,3...</math> for each rank.

<gallery perrow="4" widths="200px" heights="400px" mode="nolines">
File:Rank3CompactHyperbolicDynkins1-31bw.svg
File:Rank3NonCompactHyperbolicDynkins32-75bw.svg
File:Rank3NonCompactHyperbolicDynkins76-123bw.svg
File:Rank4HyperbolicDynkins124-176bw.svg
File:Rank5HyperbolicDynkins177-198bw.svg
File:Rank6HyperbolicDynkins199-205bw.svg
File:Rank6HyperbolicDynkins206-212bw.svg
File:Rank6HyperbolicDynkins213-220bw.svg
File:Rank7HyperbolicDynkins221-224bw.svg
File:Rank8HyperbolicDynkins225-229bw.svg
File:Rank9HyperbolicDynkins230-234bw.svg
File:Rank10HyperbolicDynkins235-238bw.svg
</gallery>

===Very-extended===
Very-extended groups are [[Lorentz group]]s, defined by adding three nodes to the finite groups. The E<sub>8</sub>, E<sub>7</sub>, E<sub>6</sub>, F<sub>4</sub>, and G<sub>2</sub> offer six series ending as very-extended groups. Other extended series not shown can be defined from A<sub>n</sub>, B<sub>n</sub>, C<sub>n</sub>, and D<sub>n</sub>, as different series for each ''n''. The determinant of the associated [[Cartan matrix]] determine where the series changes from finite (positive) to affine (zero) to a noncompact hyperbolic group (negative), and ending as a Lorentz group that can be defined with the use of one [[time-like]] dimension, and is used in [[M theory]].<ref>{{Cite journal |arxiv = hep-th/0304206|bibcode = 2003JHEP...09..020E|title = The symmetry of M-theories|last1 = Englert|first1 = François|last2 = Houart|first2 = Laurent|last3 = Taormina|first3 = Anne|author3-link= Anne Taormina |last4 = West|first4 = Peter|journal = Journal of High Energy Physics|volume = 2003|issue = 9|pages = 020|year = 2003|doi = 10.1088/1126-6708/2003/09/020|s2cid = 15680493}}</ref>

{| class=wikitable
|+ Rank 2 extended series
|-
!Finite
!<math>A_2</math>
!<math>C_2</math>
![[G2 (mathematics)|<math>G_2</math>]]
|- align=center
!2
|BGCOLOR="#ffffe0"|A<sub>2</sub>{{Dynkin2|branch}}
|BGCOLOR="#ffffe0"|C<sub>2</sub>{{Dynkin|node|4a|node}}
|BGCOLOR="#ffffe0"|G<sub>2</sub>{{Dynkin|node|6a|node}}
|- align=center
!3
|BGCOLOR="#ffe0e0"|<math>A_2^+={\tilde{A}}_{2}</math>[http://commons.wikimedia.org/wiki/File:DynkinA2Affine.svg <br>{{Dynkin|branch|loop2g}}]
|BGCOLOR="#ffe0e0"|<math>C_2^+={\tilde{C}}_{2}</math>[http://commons.wikimedia.org/wiki/File:DynkinC2Affine.svg <br>{{Dynkin|node|4b|node|4a|nodeg}}]
|BGCOLOR="#ffe0e0"|<math>G_2^+={\tilde{G}}_{2}</math>[http://commons.wikimedia.org/wiki/File:DynkinG2Affine.svg <br>{{Dynkin|node|6a|node|3|nodeg}}]
|- align=center
!4
|BGCOLOR="#e0ffe0"|A<sub>2</sub><sup>++</sup>[http://commons.wikimedia.org/wiki/File:HyberbolicAffineA2.svg <br>{{Dynkin|branch|loop2g|3|nodeg}}]
|BGCOLOR="#e0ffe0"|C<sub>2</sub><sup>++</sup>[http://commons.wikimedia.org/wiki/File:HyberbolicAffineC2.svg <br>{{Dynkin|node|4b|node|4a|nodeg|3|nodeg}}]
|BGCOLOR="#e0ffe0"|G<sub>2</sub><sup>++</sup>[http://commons.wikimedia.org/wiki/File:HyberbolicAffineG2.svg <br>{{Dynkin|node|6a|node|3|nodeg|3|nodeg}}]
|- align=center
!5
|BGCOLOR="#e0e0ff"|A<sub>2</sub><sup>+++</sup>[http://commons.wikimedia.org/wiki/File:VeryExtendedAffineA2.svg <br>{{Dynkin|branch|loop2g|3|nodeg|3|nodeg}}]
|BGCOLOR="#e0e0ff"|C<sub>2</sub><sup>+++</sup>[http://commons.wikimedia.org/wiki/File:VeryExtendedAffineC2.svg <br>{{Dynkin|node|4b|node|4a|nodeg|3|nodeg|3|nodeg}}]
|BGCOLOR="#e0e0ff"|G<sub>2</sub><sup>+++</sup>[http://commons.wikimedia.org/wiki/File:VeryExtendedAffineG2.svg <br>{{Dynkin|node|6a|node|3|nodeg|3|nodeg|3|nodeg}}]
|- align=center
!Det(''M<sub>n</sub>'')
|3(3&minus;''n'')
|2(3&minus;''n'')
|3&minus;''n''
|}

{| class=wikitable
|+ Rank 3 and 4 extended series
|-
!Finite
!<math>A_3</math>
!<math>B_3</math>
!<math>C_3</math>
!<math>A_4</math>
!<math>B_4</math>
!<math>C_4</math>
!<math>D_4</math>
![[F4 (mathematics)|<math>F_4</math>]]
|- align=center
!2
|
|A<sub>1</sub><sup>2</sup><BR>{{Dynkin|node|2|node}}
|
|
|
|
|
|A<sub>2</sub><BR>{{Dynkin2|node|3|node}}
|- align=center
!3
|BGCOLOR="#ffffe0"|A<sub>3</sub><BR>{{Dynkin2|loop1|nodes}}
|BGCOLOR="#ffffe0"|B<sub>3</sub><BR>{{Dynkin2|node|4a|branch}}
|BGCOLOR="#ffffe0"|C<sub>3</sub><BR>{{Dynkin2|node|4b|node|3|node}}
|
|B<sub>2</sub>A<sub>1</sub><BR>{{Dynkin2|node|4a|node|2|node}}
|
|A<sub>1</sub><sup>3</sup><BR>{{Dynkin2|node|2|node|2|node}}
|{{Dynkin2|node|3|node|4a|node}}
|- align=center
!4
|BGCOLOR="#ffe0e0"|<math>A_{3}^{+} = {\tilde{A}}_{3}</math><BR>{{Dynkin|loop1|nodes|loop2g}}
|BGCOLOR="#ffe0e0"|<math>B_{3}^{+} = {\tilde{B}}_{3}</math><BR>{{Dynkin2|node|4a|branch|3|nodeg}}
|BGCOLOR="#ffe0e0"|<math>C_{3}^{+} = {\tilde{C}}_{3}</math><BR>{{Dynkin|node|4b|node|3|node|4a|nodeg}}
|BGCOLOR="#ffffe0"|A<sub>4</sub><BR>{{Dynkin|branch|3s|nodes}}
|BGCOLOR="#ffffe0"|B<sub>4</sub><BR>{{Dynkin2|node|4a|node|3|branch}}
|BGCOLOR="#ffffe0"|C<sub>4</sub><BR>{{Dynkin2|node|4b|node|3|node|3|node}}
|BGCOLOR="#ffffe0"|D<sub>4</sub><BR>{{Dynkin|triplebranch1|node}}
|BGCOLOR="#ffffe0"|F<sub>4</sub><BR>{{Dynkin2|node|3|node|4a|node|3|node}}
|- align=center
!5
|BGCOLOR="#e0ffe0"|A<sub>3</sub><sup>++</sup><BR>{{Dynkin|loop1|nodes|loop2g|3|nodeg}}
|BGCOLOR="#e0ffe0"|B<sub>3</sub><sup>++</sup><BR>{{Dynkin2|node|4a|branch|3|nodeg|3|nodeg}}
|BGCOLOR="#e0ffe0"|C<sub>3</sub><sup>++</sup><BR>{{Dynkin|node|4b|node|3|node|4a|nodeg|3|nodeg}}
|BGCOLOR="#ffe0e0"|<math>A_4^+={\tilde{A}}_{4}</math><BR>{{Dynkin|branch|3s|nodes|loop2g}}
|BGCOLOR="#ffe0e0"|<math>B_4^+={\tilde{B}}_{4}</math><BR>{{Dynkin2|node|4a|node|3|branch|3|nodeg}}
|BGCOLOR="#ffe0e0"|<math>C_4^+={\tilde{C}}_{4}</math><BR>{{Dynkin2|node|4b|node|3|node|3|node|4a|nodeg}}
|BGCOLOR="#ffe0e0"|<math>D_4^+={\tilde{D}}_{4}</math><BR>{{Dynkin|triplebranch1|node|3|nodeg}}
|BGCOLOR="#ffe0e0"|<math>F_4^+={\tilde{F}}_{4}</math><BR>{{Dynkin2|node|3|node|4a|node|3|node|3|nodeg}}
|- align=center
!6
|BGCOLOR="#e0e0ff"|A<sub>3</sub><sup>+++</sup><BR>{{Dynkin|loop1|nodes|loop2g|3|nodeg|3|nodeg}}
|BGCOLOR="#e0e0ff"|B<sub>3</sub><sup>+++</sup><BR>{{Dynkin2|node|4a|branch|3|nodeg|3|nodeg|3|nodeg}}
|BGCOLOR="#e0e0ff"|C<sub>3</sub><sup>+++</sup><BR>{{Dynkin|node|4b|node|3|node|4a|nodeg|3|nodeg|3|nodeg}}
|BGCOLOR="#e0ffe0"|A<sub>4</sub><sup>++</sup><BR>{{Dynkin|branch|3s|nodes|loop2g|3|nodeg}}
|BGCOLOR="#e0ffe0"|B<sub>4</sub><sup>++</sup><BR>{{Dynkin2|node|4a|node|3|branch|3|nodeg|3|nodeg}}
|BGCOLOR="#e0ffe0"|C<sub>4</sub><sup>++</sup><BR>{{Dynkin2|node|4b|node|3|node|3|node|4a|nodeg|3|nodeg}}
|BGCOLOR="#e0ffe0"|D<sub>4</sub><sup>++</sup><BR>{{Dynkin|triplebranch1|node|3|nodeg|3|nodeg}}
|BGCOLOR="#e0ffe0"|F<sub>4</sub><sup>++</sup><BR>{{Dynkin2|node|3|node|4a|node|3|node|3|nodeg|3|nodeg}}
|- align=center
!7
|BGCOLOR="#e0e0ff"|
|BGCOLOR="#e0e0ff"|
|BGCOLOR="#e0e0ff"|
|BGCOLOR="#e0e0ff"|A<sub>4</sub><sup>+++</sup><BR>{{Dynkin|branch|3s|nodes|loop2g|3|nodeg|3|nodeg}}
|BGCOLOR="#e0e0ff"|B<sub>4</sub><sup>+++</sup><BR>{{Dynkin2|node|4a|node|3|branch|3|nodeg|3|nodeg|3|nodeg}}
|BGCOLOR="#e0e0ff"|C<sub>4</sub><sup>+++</sup><BR>{{Dynkin2|node|4b|node|3|node|3|node|4a|nodeg|3|nodeg|3|nodeg}}
|BGCOLOR="#e0e0ff"|D<sub>4</sub><sup>+++</sup><BR>{{Dynkin|triplebranch1|node|3|nodeg|3|nodeg|3|nodeg}}
|BGCOLOR="#e0e0ff"|F<sub>4</sub><sup>+++</sup><BR>{{Dynkin2|node|3|node|4a|node|3|node|3|nodeg|3|nodeg|3|nodeg}}
|- align=center
!Det(''M<sub>n</sub>'')
|4(4&minus;''n'')
|colspan=2|2(4&minus;''n'')
|5(5&minus;''n'')
|colspan=2|2(5&minus;''n'')
|4(5&minus;''n'')
|5&minus;''n''
|}

{| class=wikitable
|+ Rank 5 and 6 extended series
|-
!Finite
!<math>A_5</math>
!<math>B_5</math>
!<math>D_5</math>
!<math>A_6</math>
!<math>B_6</math>
!<math>D_6</math>
!<math>E_6</math>
|- align=center
!4
|
|B<sub>3</sub>A<sub>1</sub><BR>{{Dynkin2|node|4a|node|3|node|2|node}}
|A<sub>3</sub>A<sub>1</sub><BR>{{Dynkin2|node|3|branch|2|node}}
|
|
|
|A<sub>2</sub><sup>2</sup><BR>{{Dynkin|nodes|3s|nodes}}
|- align=center
!5
|BGCOLOR="#ffffe0"|A<sub>5</sub><BR>{{Dynkin|loop1|nodes|3s|nodes}}
|BGCOLOR="#ffffe0"|{{Dynkin2|node|4a|node|3|node|3|branch}}
|BGCOLOR="#ffffe0"|D<sub>5</sub><BR>{{Dynkin2|node|3|branch|3|branch}}
|
|B<sub>4</sub>A<sub>1</sub><BR>{{Dynkin2|node|4a|node|3|node|3|node|2|node}}
|D<sub>4</sub>A<sub>1</sub><BR>{{Dynkin2|node|3|branch|3|node|2|node}}
|A<sub>5</sub><BR>{{Dynkin|nodes|3s|nodes|loop2}}
|- align=center
!6
|BGCOLOR="#ffe0e0"|<math>A_5^+={\tilde{A}}_5</math><BR>{{Dynkin|loop1|nodes|3s|nodes|loop2g}}
|BGCOLOR="#ffe0e0"|<math>B_5^+={\tilde{B}}_{5}</math><BR>{{Dynkin2|node|4a|node|3|node|3|branch|3|nodeg}}
|BGCOLOR="#ffe0e0"|<math>D_5^+={\tilde{D}}_5</math><BR>{{Dynkin2|node|3|branch|3|branch|3|nodeg}}
|BGCOLOR="#ffffe0"|A<sub>6</sub><BR>{{Dynkin2|branch|3s|nodes|3s|nodes}}
|BGCOLOR="#ffffe0"|B<sub>6</sub><BR>{{Dynkin2|node|4a|node|3|node|3|node|3|branch}}
|BGCOLOR="#ffffe0"|D<sub>6</sub><BR>{{Dynkin2|node|3|branch||3|node|3|branch}}
|BGCOLOR="#ffffe0"|E<sub>6</sub><BR>{{Dynkin|nodes|3s|nodes|loop2|3|node}}
|- align=center
!7
|BGCOLOR="#e0ffe0"|A<sub>5</sub><sup>++</sup><BR>{{Dynkin|loop1|nodes|3s|nodes|loop2g|3|nodeg}}
|BGCOLOR="#e0ffe0"|B<sub>5</sub><sup>++</sup><BR>{{Dynkin2|node|4a|node|3|node|3|branch|3|nodeg|3|nodeg}}
|BGCOLOR="#e0ffe0"|D<sub>5</sub><sup>++</sup><BR>{{Dynkin2|node|3|branch|3|branch|3|nodeg|3|nodeg}}
|BGCOLOR="#ffe0e0"|<math>A_6^+={\tilde{A}}_6</math><BR>{{Dynkin|branch|3s|nodes|3s|nodes|loop2g}}
|BGCOLOR="#ffe0e0"|<math>B_6^+={\tilde{B}}_{6}</math><BR>{{Dynkin2|node|4a|node|3|node|3|node|3|branch|3|nodeg}}
|BGCOLOR="#ffe0e0"|<math>D_6^+={\tilde{D}}_6</math><BR>{{Dynkin2|node|3|branch|3|node|3|branch|3|nodeg}}
|BGCOLOR="#ffe0e0"|<math>E_6^+={\tilde{E}}_6</math><BR>{{Dynkin|nodes|3s|nodes|loop2|3|node|3|nodeg}}
|- align=center
!8
|BGCOLOR="#e0e0ff"|A<sub>5</sub><sup>+++</sup><BR>{{Dynkin|loop1|nodes|3s|nodes|loop2g|3|nodeg|3|nodeg}}
|BGCOLOR="#e0e0ff"|B<sub>5</sub><sup>+++</sup><BR>{{Dynkin2|node|4a|node|3|node|3|branch|3|nodeg|3|nodeg|3|nodeg}}
|BGCOLOR="#e0e0ff"|D<sub>5</sub><sup>+++</sup><BR>{{Dynkin2|node|3|branch|3|branch|3|nodeg|3|nodeg|3|nodeg}}
|BGCOLOR="#e0ffe0"|A<sub>6</sub><sup>++</sup><BR>{{Dynkin|branch|3s|nodes|3s|nodes|loop2g|3|nodeg}}
|BGCOLOR="#e0ffe0"|B<sub>6</sub><sup>++</sup><BR>{{Dynkin2|node|4a|node|3|node|3|node|3|branch|3|nodeg|3|nodeg}}
|BGCOLOR="#e0ffe0"|D<sub>6</sub><sup>++</sup><BR>{{Dynkin2|node|3|branch|3|node|3|branch|3|nodeg|3|nodeg}}
|BGCOLOR="#e0ffe0"|E<sub>6</sub><sup>++</sup><BR>{{Dynkin|nodes|3s|nodes|loop2|3|node|3|nodeg|3|nodeg}}
|- align=center
!9
|BGCOLOR="#e0e0ff"|
|BGCOLOR="#e0e0ff"|
|BGCOLOR="#e0e0ff"|
|BGCOLOR="#e0e0ff"|A<sub>6</sub><sup>+++</sup><BR>{{Dynkin|branch|3s|nodes|3s|nodes|loop2g|3|nodeg|3|nodeg}}
|BGCOLOR="#e0e0ff"|B<sub>6</sub><sup>+++</sup><BR>{{Dynkin2|node|4a|node|3|node|3|node|3|branch|3|nodeg|3|nodeg|3|nodeg}}
|BGCOLOR="#e0e0ff"|D<sub>6</sub><sup>+++</sup><BR>{{Dynkin2|node|3|branch|3|node|3|branch|3|nodeg|3|nodeg|3|nodeg}}
|BGCOLOR="#e0e0ff"|E<sub>6</sub><sup>+++</sup><BR>{{Dynkin|nodes|3s|nodes|loop2|3|node|3|nodeg|3|nodeg|3|nodeg}}
|- align=center
!Det(''M<sub>n</sub>'')
|6(6&minus;''n'')
|2(6&minus;''n'')
|4(6&minus;''n'')
|7(7&minus;''n'')
|2(7&minus;''n'')
|4(7&minus;''n'')
|3(7&minus;''n'')
|}

{| class=wikitable
|+ Some rank 7 and higher extended series
|-
!Finite
!A<sub>7</sub>
!B<sub>7</sub>
!D<sub>7</sub>
!E<sub>7</sub>
![[En (Lie algebra)|E<sub>8</sub>]]
|- align=center
!3
|
|
|
|
|E<sub>3</sub>=A<sub>2</sub>A<sub>1</sub><BR>{{Dynkin2|node|3|node|2|node}}
|- align=center
!4
|
|
|
|A<sub>3</sub>A<sub>1</sub><BR>{{Dynkin2|node|3|node|3|node|2|node}}
|E<sub>4</sub>=A<sub>4</sub><BR>{{Dynkin2|node|3|node|3|branch}}
|- align=center
!5
|
|
|
|A<sub>5</sub><BR>{{Dynkin2|node|3|node|3|node|3|branch}}
|E<sub>5</sub>=D<sub>5</sub><BR>{{Dynkin2|node|3|node|3|branch|3|node}}
|- align=center
!6
|
|B<sub>5</sub>A<sub>1</sub><BR>{{Dynkin2|node|4a|node|3|node|3|node|3|node|2|node}}
|D<sub>5</sub>A<sub>1</sub><BR>{{Dynkin2|node|3|branch|3|node|3|node|2|node}}
|D<sub>6</sub><BR>{{Dynkin2|node|3|node|3|node|3|branch|3|node}}
|E<sub>6</sub> [http://commons.wikimedia.org/wiki/File:DynkinE6Full.svg <br>{{Dynkin2|node|3|node|3|branch|3|node|3|node}}]
|- align=center
!7
|BGCOLOR="#ffffe0"|A<sub>7</sub><BR>{{Dynkin|loop1|nodes|3s|nodes|3s|nodes}}
|BGCOLOR="#ffffe0"|B<sub>7</sub><BR>{{Dynkin2|node|4a|node|3|node|3|node|3|node|3|branch}}
|BGCOLOR="#ffffe0"|D<sub>7</sub><BR>{{Dynkin2|node|3|branch|3|node|3|node|3|branch}}
|BGCOLOR="#ffffe0"|E<sub>7</sub> [http://commons.wikimedia.org/wiki/File:DynkinE7Full.svg <br>{{Dynkin2|node|3|node|3|node|3|branch|3|node|3|node}}]
|E<sub>7</sub> [http://commons.wikimedia.org/wiki/File:DynkinE7Full.svg <br>{{Dynkin2|node|3|node|3|branch|3|node|3|node|3|node}}]
|- align=center
!8
|BGCOLOR="#ffe0e0"|<math>A_7^+={\tilde{A}}_7</math> [http://commons.wikimedia.org/wiki/File:AffineA7.svg <br>{{Dynkin|loop1|nodes|3s|nodes|3s|nodes|loop2g}}]
|BGCOLOR="#ffe0e0"|<math>B_7^+={\tilde{B}}_{7}</math> [http://commons.wikimedia.org/wiki/File:AffineB7.svg <br>{{Dynkin2|node|4a|node|3|node|3|node|3|node|3|branch|3|nodeg}}]
|BGCOLOR="#ffe0e0"|<math>D_7^+={\tilde{D}}_7</math> [http://commons.wikimedia.org/wiki/File:AffineD7.svg <br>{{Dynkin2|node|3|branch|3|node|3|node|3|branch|3|nodeg}}]
|BGCOLOR="#ffe0e0"|<math>E_7^+={\tilde{E}}_{7}</math> [http://commons.wikimedia.org/wiki/File:AffineE7.svg <br>{{Dynkin2|node|3|node|3|node|3|branch|3|node|3|node|3|nodeg}}]
|BGCOLOR="#ffffe0"|E<sub>8</sub> [http://commons.wikimedia.org/wiki/File:DynkinE8Full.svg|<br>{{Dynkin2|node|3|node|3|branch|3|node|3|node|3|node|3|node}}]
|- align=center
!9
|BGCOLOR="#e0ffe0"|A<sub>7</sub><sup>++</sup> [http://commons.wikimedia.org/wiki/File:HyberbolicAffineA7.svg <br>{{Dynkin|loop1|nodes|3s|nodes|3s|nodes|loop2g|3|nodeg}}]
|BGCOLOR="#e0ffe0"|B<sub>7</sub><sup>++</sup> [http://commons.wikimedia.org/wiki/File:HyberbolicAffineB7.svg <br>{{Dynkin2|node|4a|node|3|node|3|node|3|node|3|branch|3|nodeg|3|nodeg}}]
|BGCOLOR="#e0ffe0"|D<sub>7</sub><sup>++</sup> [http://commons.wikimedia.org/wiki/File:HyberbolicAffineD7.svg <br>{{Dynkin2|node|3|branch|3|node|3|node|3|branch|3|nodeg|3|nodeg}}]
|BGCOLOR="#e0ffe0"|E<sub>7</sub><sup>++</sup> [http://commons.wikimedia.org/wiki/File:HyberbolicAffineE7.svg <br>{{Dynkin2|node|3|node|3|node|3|branch|3|node|3|node|3|nodeg|3|nodeg}}]
|BGCOLOR="#ffe0e0"|<math>E_9=E_8^+={\tilde{E}}_{8}</math> [http://commons.wikimedia.org/wiki/File:E9-AffineE8.svg <br>{{Dynkin2|node|3|node|3|branch|3|node|3|node|3|node|3|node|3|nodeg}}]
|- align=center
!10
|BGCOLOR="#e0e0ff"|A<sub>7</sub><sup>+++</sup> [http://commons.wikimedia.org/wiki/File:VeryExtendedAffineA7.svg <br>{{Dynkin|loop1|nodes|3s|nodes|3s|nodes|loop2g|3|nodeg|3|nodeg}}]
|BGCOLOR="#e0e0ff"|B<sub>7</sub><sup>+++</sup> [http://commons.wikimedia.org/wiki/File:VeryExtendedAffineB7.svg <br>{{Dynkin2|node|4a|node|3|node|3|node|3|node|3|branch|3|nodeg|3|nodeg|3|nodeg}}]
|BGCOLOR="#e0e0ff"|D<sub>7</sub><sup>+++</sup> [http://commons.wikimedia.org/wiki/File:VeryExtendedAffineD7.svg <br>{{Dynkin2|node|3|branch|3|node|3|node|3|branch|3|nodeg|3|nodeg|3|nodeg}}]
|BGCOLOR="#e0e0ff"|E<sub>7</sub><sup>+++</sup> [http://commons.wikimedia.org/wiki/File:VeryExtendedAffineE7.svg <br>{{Dynkin2|node|3|node|3|node|3|branch|3|node|3|node|3|nodeg|3|nodeg|3|nodeg}}]
|BGCOLOR="#e0ffe0"|E<sub>10</sub>=E<sub>8</sub><sup>++</sup> [http://commons.wikimedia.org/wiki/File:E10-HyperbolicAffineE8.svg <br>{{Dynkin2|node|3|node|3|branch|3|node|3|node|3|node|3|node|3|nodeg|3|nodeg}}]
|- align=center
!11
|BGCOLOR="#e0e0ff"|
|BGCOLOR="#e0e0ff"|
|BGCOLOR="#e0e0ff"|
|BGCOLOR="#e0e0ff"|
|BGCOLOR="#e0e0ff"|E<sub>11</sub>=E<sub>8</sub><sup>+++</sup> [http://commons.wikimedia.org/wiki/File:E11-VeryExtendedAffineE8.svg<br>{{Dynkin2|node|3|node|3|branch|3|node|3|node|3|node|3|node|3|nodeg|3|nodeg|3|nodeg}}]
|- align=center
!Det(''M<sub>n</sub>'')
|8(8&minus;''n'')
|2(8&minus;''n'')
|4(8&minus;''n'')
|2(8&minus;''n'')
|9&minus;''n''
|}

== See also ==
{{Commons category|Dynkin diagrams}}
* [[Satake diagram]]
* [[List of irreducible Tits indices]]
* [[wikibooks:de:Beweisarchiv: Lie-Algebren: Wurzelsysteme: Klassifikation von Wurzelsystemen|Klassifikation von Wurzelsystemen]] (Classification of root systems) {{in lang|de}}

== Notes ==
{{Reflist|group=note}}

== Citations ==
{{Reflist}}

== References ==
{{Refbegin}}
* {{citation | last = Dynkin | first = E. B. | author-link = Eugene Dynkin | title = The structure of semi-simple algebras . | journal = Uspekhi Mat. Nauk | series = N.S. | volume = 2 | year = 1947 | number = 4(20) | pages = 59–127 |language=ru}}
* {{citation
| author-link = Nicolas Bourbaki
| first = Nicolas | last = Bourbaki | year = 1968 | title = Groupes et algebres de Lie | chapter = Chapters 4–6 | publisher = Hermann | location = Paris }}
* {{Citation
| publisher = CRC Press
| isbn = 978-0-8247-1326-3
| last = Jacobson
| first = Nathan
| author-link = Nathan Jacobson
| title = Exceptional Lie Algebras
| date = 1971-06-01
}}
* {{citation |title=Introduction to Lie Algebras and Representation Theory |first=James E. |last=Humphreys |publisher=Birkhäuser |year=1972 |isbn=978-0-387-90053-7 |url-access=registration |url=https://archive.org/details/introductiontoli00jame }}
* {{Fulton-Harris}}
* {{Citation
| publisher = AMS Bookstore
| isbn = 978-0-8218-1065-1
| last1 = Dynkin
| first1 = Evgeniĭ Borisovich
| author2 = Alexander Adolph Yushkevich
| author3 = Gary M. Seitz
| author4 = A. L. Onishchik
| title = Selected papers of E.B. Dynkin with commentary
| year = 2000
}}
* {{Citation| last=Hall|first=Brian C.|title=Lie Groups, Lie Algebras, and Representations: An Elementary Introduction|edition=2nd|series=Graduate Texts in Mathematics|volume=222|publisher=Springer|year=2015|isbn=978-3319134666}}
* {{Citation
| publisher = Birkhäuser
| isbn = 978-0-8176-4259-4
| last = Knapp
| first = Anthony W.
| title = Lie groups beyond an introduction
| edition = 2nd
| year = 2002
}}
* {{Citation
| title = Notes on Coxeter Transformations and the McKay Correspondence | series = Springer Monographs in Mathematics | first = R. | last = Stekolshchik
| year = 2008 | isbn = 978-3-540-77398-6 <!--hardcover-->
| doi = 10.1007/978-3-540-77399-3 
| arxiv = math/0510216 | s2cid = 117958873 }}
* {{Citation
|last1=Carbone |first1= Lisa |last2=Chung |first2=Sjuvon |last3=Cobbs |first3=Leigh |last4=Mcrae |first4=Robert |last5=Nandi |first5=Debajyoti |last6=Navqi |first6=Yusra |last7=Penta |first7=Diego 
|date=March 2010 
|title=Classification of hyperbolic Dynkin diagrams, root lengths and Weyl group orbits. 
|url=https://sites.math.rutgers.edu/~sefiroth/HypClass.pdf 
|journal=Journal of Physics A: Mathematical and Theoretical 
|volume=43 
|issue=15  
|page= 155209 |doi=10.1088/1751-8113/43/15/155209 
|arxiv= 1003.0564 |bibcode= 2010JPhA...43o5209C |mr=2608277 |s2cid=16946456 }}
* {{cite book |last1=Kac |first1=Victor G. |title=Infinite-Dimensional Lie Algebras |date=1994 |publisher=Cambridge University Press |isbn=978-0-521-46693-6 |url=https://books.google.com/books?id=kuEjSb9teJwC |language=en}}
* {{Cite book |last1=Dynkin |first1=Eugene B. |editor1-last=Yushkevich |editor1-first=A. A. |editor2-last=[[Gary Seitz|Seitz]] |editor2-first=G. M. |editor3-last=Onishchik |editor3-first=A. L. |title=Selected papers of E. B. Dynkin with commentary |url=https://books.google.com/books?id=D9ZF5O_JH2gC |publisher=American Mathematical Society |location=Providence, R.I. |isbn=978-0-8218-1065-1 |mr=1757976 |year=2000}}
{{Refend}}

== External links ==
* [http://math.ucr.edu/home/baez/week230.html John Baez on the ubiquity of Dynkin diagrams in mathematics]
* [http://lesha.goder.com/dynkin-diagrams.html Web tool for making publication-quality Dynkin diagrams with labels (written in JavaScript)]

{{Authority control}}

{{DEFAULTSORT:Dynkin Diagram}}
[[Category:Lie algebras]]