Testwiki:Reference desk/Archives/Computing/2025 January 15

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January 15

What is this character?

Inequality (mathematics) has several characters that my computer renders as little boxes. For example:

• a <⃥͏ a (irreflexivity) — after the first italic a
• if a < b, then b <⃥͏ a (asymmetry) — after the second italic b

What are they? In both cases that I copied, the box is seemingly the same character as the lesser-than sign, since I can't highlight one without the other. I figured I could get the answer from Google (there are enough Unicode charts online), but I get just four results for the combined lesser-than-and-box: the inequality article, two Reddit pages, and something in Thai. When I put the combined lesser-than-and-box into the URL, I'm shown MediaWiki:Badtitletext, which makes sense for a title containing a standalone < character, but not for one where the < elements are part of a special character. Nyttend (talk) 20:29, 15 January 2025 (UTC)

A less-than with two combining codes:

index  chr codepoint utf8    cat  name
 0      <  U+003c    3c      Sm   LESS-THAN SIGN
 1       ⃥  U+20e5    e283a5  Mn   COMBINING REVERSE SOLIDUS OVERLAY
 2       ͏  U+034f    cd8f    Mn   COMBINING GRAPHEME JOINER

-- Finlay McWalter··–·Talk 22:56, 15 January 2025 (UTC)

In other words, it's a "not less than" sign. Unicode's single character for that is hex 226E or ≮, although it uses a slash rather than a backslash ("reverse solidus") to overstrike the < sign. --142.112.149.206 (talk) 02:47, 16 January 2025 (UTC)

Latex also uses $\nless .$ The use of a forward slash, as in $a\text{R}b,$ to mean $\mathrm{\neg }(a\text{R}b),$ is standard. I can't think of a reason for using the backslashed symbol $<\setminus$ instead and have replaced <\ by ≮.  --Lambiam 09:27, 16 January 2025 (UTC)