mjo-algebra: add \Stab command for stabilizer subgroups.

[mjotex.git] / mjo-algebra.tex

diff --git a/mjo-algebra.tex b/mjo-algebra.tex
index 7ff7b5ae737ac2c14cbe4eda7af0a4f72fde2a5d..1ab88806c2cdad1caa64bfb62ea860496e820db9 100644 (file)
--- a/mjo-algebra.tex
+++ b/mjo-algebra.tex
@@ -12,6 +12,30 @@
 \input{mjo-common} % for \of, and \binopmany
 
 
+% The additive identity element of its argument, which should be
+% an algebraic structure.
+\newcommand*{\zero}[1]{ 0_{{#1}} }
+
+\ifdefined\newglossaryentry
+  \newglossaryentry{zero}{
+    name={\ensuremath{\zero{R}}},
+    description={the additive identity element of $R$},
+    sort=z
+  }
+\fi
+
+% The multiplicative identity element of its argument, which should be
+% an algebraic structure.
+\newcommand*{\unit}[1]{ 1_{{#1}} }
+
+\ifdefined\newglossaryentry
+  \newglossaryentry{unit}{
+    name={\ensuremath{\unit{R}}},
+    description={the multiplicative identity (unit) element of $R$},
+    sort=u
+  }
+\fi
+
 % The direct sum of two things.
 \newcommand*{\directsum}[2]{ {#1}\oplus{#2} }
 
@@ -66,4 +90,8 @@
 \fi
 
 
+% The stabilizer subgroup of its first argument that fixes the point
+% given by its second argument.
+\newcommand*{\Stab}[2]{ #1_{#2} }
+
 \fi