\def\sum{\mathop{\ifdisplay\@displaysum\else\@sum\fi}}
\def\prod{\mathop{\ifdisplay\@displayprod\else\@prod\fi}}
\def\coprod{\mathop{\ifdisplay\@displaycoprod\else\@coprod\fi}}
\def\intop{\mathop{\ifdisplay\@displayint\else{\large\@int}\fi}}
\def\int{\intop\intlimits}
\def\ointop{\mathop{\ifdisplay\@displayoint\else{\large\@oint}\fi}}
\def\oint{\ointop\intlimits}
\def\bigcap{\mathop{{\ifdisplay\Huge\fi\cap}}}
\def\bigcup{\mathop{{\ifdisplay\Huge\fi\cup}}}
\def\bigvee{\mathop{{\ifdisplay\Huge\fi\vee}}}
\def\bigwedge{\mathop{{\ifdisplay\Huge\fi\wedge}}}
\def\bigsqcup{\mathop{{\ifdisplay\Huge\fi\sqcup}}}
\def\bigodot{\mathop{{\ifdisplay\Huge\fi\odot}}}
\def\bigoplus{\mathop{{\ifdisplay\Huge\fi\oplus}}}
\def\biguplus{\mathop{{\ifdisplay\Huge\fi\uplus}}}
\def\bigotimes{\mathop{{\ifdisplay\Huge\fi\otimes}}}
\def\Updownarrow{\mathop{\ifdisplay\@displayUpdownarrow\else\@updownarrow\fi}}