List of logic symbols

In logic, a set of symbols is commonly used to express logical representation. The following table lists many common symbols, together with their name, how they should be read out loud, and the related field of mathematics. Additionally, the subsequent columns contain an informal explanation, a short example, the Unicode location, the name for use in HTML documents, and the LaTeX symbol.

Basic logic symbols

Symbol	Unicode value (hexadecimal)	HTML codes	LaTeX symbol	Logic Name	Read as	Category	Explanation	Examples
Template:Huge	Template:Mono	Template:Mono ⇒	$\Rightarrow$ Template:Mono $⟹$ Template:Mono	material conditional (material implication)	implies, if P then Q, it is not the case that P and not Q	propositional logic, Boolean algebra, Heyting algebra	$A\Rightarrow B$ is false when Template:Mvar is true and Template:Mvar is false but true otherwise. In other mathematical contexts, see glossary of mathematical symbols, $\to$ may indicate the domain and codomain of a function and $\supset$ may mean superset.	$x=2\Rightarrow x^2=4$ is true, but $x^2=4\Rightarrow x=2$ is in general false (since Template:Mvar could be −2).
Template:Huge	Template:Mono	Template:Mono	$\to$ \to or \rightarrow
Template:Huge	Template:Mono	Template:Mono	$\supset$ \supset
Template:Huge	Template:Mono	Template:Mono	$\iff$ Template:Mono $⟺$ Template:Mono	material biconditional (material equivalence)	if and only if, iff, xnor	propositional logic, Boolean algebra	$A\iff B$ is true only if both Template:Mvar and Template:Mvar are false, or both Template:Mvar and Template:Mvar are true. Whether a symbol means a material biconditional or a logical equivalence, depends on the author's style.	$x+5=y+2\iff x+3=y$
Template:Huge	Template:Mono	Template:Mono	$\leftrightarrow$ Template:Mono
Template:Huge	Template:Mono	Template:Mono	$\equiv$ Template:Mono
Template:Huge	Template:Mono	Template:Mono	$\mathrm{\neg }$ Template:Mono	negation	not	propositional logic, Boolean algebra	The statement $\mathrm{\neg }A$ is true if and only if Template:Mvar is false. A slash placed through another operator is the same as $\mathrm{\neg }$ placed in front. The prime symbol is placed after the negated thing, e.g. $p^{\prime }$	$\mathrm{\neg }(\mathrm{\neg }A)\iff A$ $x\ne y\iff \mathrm{\neg }(x=y)$
Template:Huge	Template:Mono	Template:Mono	$\sim$ Template:Mono
Template:Huge	Template:Mono	Template:Mono	$\mathrm{\neg }$ Template:Mono or Template:Mono
Template:Huge	Template:Mono	Template:Mono	${{\displaystyle }}^{\prime }$ Template:Mono
Template:Huge	Template:Mono	Template:Mono	$\wedge$ Template:Mono or Template:Mono	logical conjunction	and	propositional logic, Boolean algebra	The statement A ∧ B is true if A and B are both true; otherwise, it is false.	Template:Math Template:Math Template:Math when n is a natural number.
Template:Huge	Template:Mono	Template:Mono	$\cdot$ Template:Mono
Template:Huge	Template:Mono	Template:Mono	$\mathrm{\&}$ Template:Mono
Template:Huge	Template:Mono	Template:Mono	$\vee$ Template:Mono	logical (inclusive) disjunction	or	propositional logic, Boolean algebra	The statement A ∨ B is true if A or B (or both) are true; if both are false, the statement is false.	Template:Math when n is a natural number.
Template:Huge	Template:Mono	Template:Mono
Template:Huge	Template:Mono	Template:Mono	$\parallel$ Template:Mono
Template:Huge	Template:Mono	Template:Mono Template:Mono	$\oplus$ Template:Mono	exclusive disjunction	xor, either ... or ... (but not both)	propositional logic, Boolean algebra	The statement $A\oplus B$ is true when either A or B, but not both, are true. This is equivalent to ¬(A ↔ B), hence the symbols $\nleftrightarrow$ and $\equiv ̸$.	$\mathrm{\neg }A\oplus A$ is always true and $A\oplus A$ is always false (if vacuous truth is excluded).
Template:Huge	Template:Mono	Template:Mono Template:Mono	$⊻$ Template:Mono
Template:Huge	Template:Mono	Template:Mono	$\leftrightarrow ̸$ Template:Mono
Template:Huge	Template:Mono	Template:Mono Template:Mono	$\equiv ̸$ Template:Mono
Template:Huge	Template:Mono	Template:Mono	$\mathrm{\top }$ Template:Mono	true (tautology)	top, truth, tautology, verum, full clause	propositional logic, Boolean algebra, first-order logic	$\mathrm{\top }$ denotes a proposition that is always true.	The proposition $\mathrm{\top }\vee P$ is always true since at least one of the two is unconditionally true.
Template:Huge
Template:Huge
Template:Huge	Template:Mono	Template:Mono	$\mathrm{\perp }$ Template:Mono	false (contradiction)	bottom, falsity, contradiction, falsum, empty clause	propositional logic, Boolean algebra, first-order logic	$\mathrm{\perp }$ denotes a proposition that is always false. The symbol ⊥ may also refer to perpendicular lines.	The proposition $\mathrm{\perp }\wedge P$ is always false since at least one of the two is unconditionally false.
Template:Huge
Template:Huge
Template:Huge	Template:Mono	Template:Mono ∀	$\mathrm{\forall }$ Template:Mono	universal quantification	given any, for all, for every, for each, for any	first-order logic	$\mathrm{\forall }x$ $P(x)$ or $(x)$ $P(x)$ says "given any $x$, $x$ has property $P$."	$\mathrm{\forall }n\in \mathbb{N}:n^2\ge n.$
Template:Huge
Template:Huge	Template:Mono	Template:Mono	$\mathrm{\exists }$ Template:Mono	existential quantification	there exists, for some	first-order logic	$\mathrm{\exists }x$ $P(x)$ says "there exists an $x$ (at least one) such that $x$ has property $P$."	$\mathrm{\exists }n\in \mathbb{N}:$ n is even.
Template:Huge	Template:Mono	Template:Mono ∃!	Template:Mono	uniqueness quantification	there exists exactly one	first-order logic (abbreviation)	$\mathrm{\exists }!x$ $P(x)$ says "there exists exactly one $x$ such that $x$ has property $P$." Only $\mathrm{\forall }$ and $\mathrm{\exists }$ are part of formal logic. $\mathrm{\exists }!x$ $P(x)$ is an abbreviation for $\mathrm{\exists }x\mathrm{\forall }y(P(y)\leftrightarrow y=x)$	$\mathrm{\exists }!n\in \mathbb{N}:n+5=2n.$
Template:Huge	Template:Mono Template:Mono	Template:Mono Template:Mono ( )	$()$ Template:Mono	precedence grouping	parentheses; brackets	almost all logic syntaxes, as well as metalanguage	Perform the operations inside the parentheses first.	Template:Math, but Template:Math.
Template:Huge	Template:Mono	Template:Mono 𝔻	Template:Mono	domain of discourse	domain of discourse	metalanguage (first-order logic semantics)		$𝔻\mathbb{:}ℝ$
Template:Huge	Template:Mono	Template:Mono ⊢	Template:Mono	syntactic consequence	proves, syntactically entails (single) turnstile	metalanguage (metalogic)	$A⊢B$ says "$B$ is a theorem of $A$". In other words, $A$ proves $B$ via a deductive system.	$(A\to B)⊢(\mathrm{\neg }B\to \mathrm{\neg }A)$ (eg. by using natural deduction)
Template:Huge	Template:Mono	Template:Mono	Template:Mono	semantic consequence or satisfaction	(semantically) entails or satisfies, models double turnstile	metalanguage (metalogic)	$A\models B$ says "in every model, it is not the case that $A$ is true and $B$ is false". $ℳ,\sigma \models B$ says a formula $B$ is true in a model $ℳ$ with variable assignment $\sigma$.	$(A\to B)\models (\mathrm{\neg }B\to \mathrm{\neg }A)$ (eg. by using truth tables)
Template:Huge	Template:Mono	Template:Mono	$\equiv$ Template:Mono	logical equivalence	is logically equivalent to	metalanguage (metalogic)	It's when $A\models B$ and $B\models A$. Whether a symbol means a material biconditional or a logical equivalence, depends on the author's style.	$(A\to B)\equiv (\mathrm{\neg }A\vee B)$
Template:Huge	Template:Mono
Template:Huge	Template:Mono	Template:Mono	$\iff$ Template:Mono
Template:Huge	Template:Mono		⊬ Template:Mono		does not syntactically entail (does not prove)	metalanguage (metalogic)	$A⊬B$ says "$B$ is not a theorem of $A$". In other words, $B$ is not derivable from $A$ via a deductive system.	$A\vee B⊬A\wedge B$
Template:Huge	Template:Mono		Template:Mono		does not semantically entail	metalanguage (metalogic)	$A⊭B$ says "$A$ does not guarantee the truth of $B$ ". In other words, $A$ does not make $B$ true.	$A\vee B⊭A\wedge B$
Template:Huge	Template:Mono		Template:Mono	necessity (in a model)	box; it is necessary that	modal logic	modal operator for "it is necessary that" in alethic logic, "it is provable that" in provability logic, "it is obligatory that" in deontic logic, "it is believed that" in doxastic logic, "it is known that" in autoepistemic logic.	$◻\mathrm{\forall }xP(x)$ says "it is necessary that everything has property $P$"
Template:Huge	Template:Mono		$◊$ Template:Mono	possibility (in a model)	diamond; it is possible that	modal logic	modal operator for "it is possible that", (in most modal logics it is defined as "¬□¬", "it is not necessarily not").	$◊\mathrm{\exists }xP(x)$ says "it is possible that something has property $P$"
Template:Huge	Template:Mono		Template:Mono	therefore	therefore	metalanguage	abbreviation for "therefore"
Template:Huge	Template:Mono		∵ Template:Mono	because	because	metalanguage	abbreviation for "because".
Template:Huge	Template:Mono	Template:Mono	≔ Template:Mono $:=$ Template:Mono	definition	is defined as	metalanguage	$a:=b$ means "from now on, $a$ is defined to be another name for $b$." This is a statement in the metalanguage, not the object language. The notation $a\equiv b$ may occasionally be seen in physics, meaning the same as $a:=b$.	$\cosh x:=\frac{e^x+e^{-x}}{2}$
Template:Huge	Template:Mono		$\triangleq$ Template:Mono
Template:Huge	Template:Mono		$\stackrel{\mathrm{d}\mathrm{e}\mathrm{f}}{=}$ \stackrel{ \scriptscriptstyle \mathrm{def}}{=}
Template:Huge	Template:Mono		$\uparrow$ Template:Mono	Sheffer stroke, NAND	NAND, not both up arrow	Propositional logic	NAND is the negation of conjunction so $A\uparrow B$ is true if and only if it's not the case that both Template:Mvar and Template:Mvar are true. See also NAND gate
Template:Huge	Template:Mono		$\mid$ Template:Mono, Template:Mono
Template:Huge	Template:Mono		$⊼$ Template:Mono
Template:Huge	Template:Mono		$\downarrow$ \downarrow	Peirce Arrow	down arrow	Propositional logic	NOR is the negation of disjunction so $A\downarrow B$ is true if and only if both Template:Mvar and Template:Mvar are false. See also NOR gate
Template:Huge	Template:Mono		$\bar{\vee }$ \overline{\vee}	NOR	nor

Advanced or rarely used logical symbols

The following symbols are either advanced and context-sensitive or very rarely used:

Symbol	Unicode value (hexadecimal)	HTML value (decimal)	HTML entity (named)	LaTeX symbol	Logic Name	Read as	Category	Explanation
⥽	U+297D			\strictif	right fish tail			Sometimes used for "relation", also used for denoting various ad hoc relations (for example, for denoting "witnessing" in the context of Rosser's trick). The fish tail is also used as strict implication by C.I.Lewis $p$ ⥽ $q\equiv ◻(p\to q)$.
̅	U+0305			\overline{x}	combining overline			Used format for denoting Gödel numbers. Using HTML style "4̅" is an abbreviation for the standard numeral "SSSS0". It may also denote a negation (used primarily in electronics).
⌜ ⌝	U+231C U+231D			\ulcorner \urcorner	top left corner top right corner			Corner quotes, also called "Quine quotes"; for quasi-quotation, i.e. quoting specific context of unspecified ("variable") expressions; also used for denoting Gödel number; for example "⌜G⌝" denotes the Gödel number of G. (Typographical note: although the quotes appears as a "pair" in unicode (231C and 231D), they are not symmetrical in some fonts. In some fonts (for example Arial) they are only symmetrical in certain sizes. Alternatively the quotes can be rendered as ⌈ and ⌉ (U+2308 and U+2309) or by using a negation symbol and a reversed negation symbol ⌐ ¬ in superscript mode.)
∄	U+2204			\nexists	there does not exist			Strike out existential quantifier. "¬∃" is sometimes used instead.
⊙	U+2299			\odot	circled dot operator			A sign for the XNOR operator (material biconditional and XNOR are the same operation).
⟛	U+27DB				left and right tack			"Proves and is proved by".
⊩	U+22A9			\Vdash	forces			One of this symbol's uses is to mean "truthmakes" in the truthmaker theory of truth. It is also used to mean "forces" in the set theory method of forcing.
⟡	U+27E1				white concave-sided diamond	never	modal operator
⟢	U+27E2				white concave-sided diamond with leftwards tick	was never	modal operator
⟣	U+27E3				white concave-sided diamond with rightwards tick	will never be	modal operator
⟤	U+25A4				white square with leftwards tick	was always	modal operator
⟥	U+25A5				white square with rightwards tick	will always be	modal operator
⋆	U+22C6			\star	star operator			May sometimes be used for ad-hoc operators.
⌐	U+2310				reversed not sign
⨇	U+2A07				two logical AND operator

See also

• Glossary of logic
• Józef Maria Bocheński
• List of notation used in Principia Mathematica
• List of mathematical symbols
• Logic alphabet, a suggested set of logical symbols
• Template:Slink
• Logical connective
• Mathematical operators and symbols in Unicode
• Non-logical symbol
• Polish notation
• Truth function
• Truth table
• Wikipedia:WikiProject Logic/Standards for notation

Further reading

• Józef Maria Bocheński (1959), A Précis of Mathematical Logic, trans., Otto Bird, from the French and German editions, Dordrecht, South Holland: D. Reidel.

External links

• Named character entities in HTML 4.0