-% The Cartesian product of two things.
-\newcommand*{\cartprod}[2]{ {#1}\times{#2} }
-
-% The Cartesian product of three things.
-\newcommand*{\cartprodthree}[3]{ \cartprod{{#1}}{\cartprod{{#2}}{{#3}}} }
-
-% The direct sum of two things.
-\newcommand*{\directsum}[2]{ {#1}\oplus{#2} }
-
-% The direct sum of three things.
-\newcommand*{\directsumthree}[3]{ \directsum{#1}{\directsum{#2}{#3}} }
-