What symbol should I use for a set complement? It seems that the \complement isn't quite appropriate: it seems taller (perhaps a unary operator to appear before a set?). I guess for now \mathsf{c} works.
asked Apr 17, 2011 at 7:43
1 Answer
As the commenters have said, there isn't a strong consensus on this one. Here are a few conventions I know about:
\documentclass{minimal}
\usepackage{amsmath}
\usepackage{amssymb}
\newcommand{\eqn}{\[
\stcomp{(A \cup B)} = \stcomp{A} \cap \stcomp{B}
\]}
\begin{document}
\newcommand{\stcomp}[1]{{#1}^\complement} \eqn
\renewcommand{\stcomp}[1]{\overline{#1}} \eqn
\renewcommand{\stcomp}[1]{{#1'}} \eqn
\renewcommand{\stcomp}[1]{\widetilde{#1}} \eqn
\renewcommand{\stcomp}[1]{{#1}^{\sim}} \eqn
\renewcommand{\stcomp}[1]{{#1}^{\mathsf{c}}} \eqn
\renewcommand{\stcomp}[1]{X\setminus{#1}} \eqn
\end{document}
Of all of these I've used ^\complement the most, and the overbar is the one I've seen the most. I have to say I really like your ^\mathsf{c} implementation.
answered Apr 17, 2011 at 10:05
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1My textbooks use the minus sign, so that $X - A$ picks out the set of members of X that aren't in A. Is the minus sign commonly used for something else?– twofeetFeb 18, 2013 at 21:04
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5If X is an abelian monoid (i.e., has a subtraction operation) then X-A could be the set of all elements of X which can be expressed as difference of elements of X and A. But I can't say that's a very popular usage. I would be reluctant to use the minus sign when
\setminusis available. Feb 20, 2013 at 20:40 -
1Twofeet, do you mean that your textbooks write $-A$ for the complement of $A$ or simply that they write $X - A$ for the set difference? Either way, I suppose that $\setminus{A}$ (or $\setminus A$) would also be an option for the complement. Dec 5, 2016 at 20:09
\complementis often used, but there's no general consensus about an "official" symbol. I've seen it denoted in several different ways (personally, I don't like\complement).