\def\havemjoalgebra{1}
-% Needed for \operatorname.
-\usepackage{amsopn}
+\ifx\operatorname\undefined
+ \usepackage{amsopn}
+\fi
+
+\input{mjo-common}
+
+
+% The (sub)algebra generated by its argument, a subset of some ambient
+% algebra. By definition this is the smallest subalgebra (of the
+% ambient one) containing that set.
+\newcommand*{\alg}[1]{\operatorname{alg}\of{{#1}}}
+\ifdefined\newglossaryentry
+ \newglossaryentry{alg}{
+ name={\ensuremath{\alg{X}}},
+ description={the (sub)algebra generated by $X$},
+ sort=a
+ }
+\fi
+
% The fraction field of its argument, an integral domain. The name
% "Frac" was chosen here instead of "Quot" because the latter
% some cases for... a quotient field (something mod something).
\newcommand*{\Frac}[1]{\operatorname{Frac}\of{{#1}}}
+% The ideal generated by its argument, a subset consisting of ring or
+% algebra elements.
+\newcommand*{\ideal}[1]{\operatorname{ideal}\of{{#1}}}
+\ifdefined\newglossaryentry
+ \newglossaryentry{ideal}{
+ name={\ensuremath{\ideal{X}}},
+ description={the ideal generated by $X$},
+ sort=i
+ }
+\fi
+
+
% The polynomial ring whose underlying commutative ring of
% coefficients is the first argument and whose indeterminates (a
% comma-separated list) are the second argumnt.