-% Needed for \operatorname.
-\usepackage{amsopn}
+%
+% Abstract algebraic structures.
+%
+\ifx\havemjoalgebra\undefined
+\def\havemjoalgebra{1}
+
+
+\ifx\operatorname\undefined
+ \usepackage{amsopn}
+\fi
% The fraction field of its argument, an integral domain. The name
% "Frac" was chosen here instead of "Quot" because the latter
% coefficients is the first argument and whose indeterminates (a
% comma-separated list) are the second argumnt.
\newcommand*{\polyring}[2]{{#1}\left[{#2}\right]}
+
+
+\fi