%
% Abstract algebraic structures.
%
+\ifx\havemjoalgebra\undefined
+\def\havemjoalgebra{1}
+
% Needed for \operatorname.
\usepackage{amsopn}
% coefficients is the first argument and whose indeterminates (a
% comma-separated list) are the second argumnt.
\newcommand*{\polyring}[2]{{#1}\left[{#2}\right]}
+
+
+\fi