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We all love normal subgroups, and in searching the web for the answer to my question I've found plenty of resources for ways to indicate normal subgroups. That's not what I'm looking for. When one wants to say $H$ is a subgroup of $G$ (not necessarily a normal subgroup, normal status is unknown), what is the intended symbol for that purpose? Does everyone just use the less-than \lt symbol? One could simply use a backslash symbol for setminus, but I'm betting parsers that automatically read LaTeX for the purposes of moving equations between math softwares probably process \setminus better. In a similar spirit, is there a LaTeX symbol for non-normal subgroup?

Edited for clarification: I am not looking for how to say "not a normal subgroup", that is, I'm not looking for a crossed out normal subgroup symbol, or a "not" symbol in front of a normal subgroup symbol. I'm looking for a standard subgroup symbol that doesn't reference "normalness" in any way.

  • Woah. And why isn't my LaTeX displaying right in the question? – Travis Bemrose Apr 13 '14 at 3:45
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    Welcome to TeX.SE. This site specifically does not render TeX unlike the math site. Can you post an image of the symbol you are looking for. Also check with detexify to see if you can find the symbol there. – Peter Grill Apr 13 '14 at 3:47
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    BTW, does \not\trianglelefteq produce what you are looking for? That is just a guess, extrapolating from Normal subgroups. – Peter Grill Apr 13 '14 at 3:51
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    Since this is a site to ask questions about TeX code it doesn't make sense to render it. See Why doesn't maths render as maths?. – Peter Grill Apr 13 '14 at 5:09
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    My teachers of group theory always used the simple \leq symbol for saying “is a subgroup of” and \unlhd for “is a normal subgroup of”. If you say “is a subgroup of”, you're supposing nothing about normality. – egreg Apr 13 '14 at 10:26
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After a bit of searching I found \leqslant, which does the trick.

4

All input so far seems to indicate that no, there's no default or standard code for subgroup, and people use some version of the inequality symbols: <, \le, etc.

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    People use different symbols. And “<” is not an “inequality symbol”, it is LESS-THAN SIGN (though it can be used to denote things other than the common arithmetic relation). – Jukka K. Korpela Apr 13 '14 at 16:43
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    In any case, you should define such a symbol: \newcommand\subgroup{\lw} or \newcommand\normsubgroup{\leq}. – Sean Allred Apr 13 '14 at 17:26
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    @JukkaK.Korpela I realize people define different platonic symbols for whatever context they're working in, and independently use various computer characters to represent those symbols, and independently display those characters in various fonts. Saying that the screen is displaying a character instead of a symbol is pointless. My statement was that since there does not seem to be any character specifically for the subgroup symbol, people use the same characters as they use for the inequality symbols. – Travis Bemrose Apr 13 '14 at 17:31
  • @JukkaK.Korpela I'd agree that making the distinction doesn't really add to the conversation; the result is the same. – Sean Allred Apr 13 '14 at 17:37
  • Tact: pointless -> moot – Travis Bemrose Apr 13 '14 at 17:45

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