\def\Longrightarrow{\lyxeq\kern-9.5mu\Rightarrow}
\def\Longleftarrow{\Leftarrow\kern-9.5mu\lyxeq}
\def\implies{\Longrightarrow}
\def\mapsto{\mapstochar\kern-9mu\rightarrow}
\def\Longrightarrow{\lyxeq\kern-9.5mu\Rightarrow}
\def\Longleftarrow{\Leftarrow\kern-9.5mu\lyxeq}
\def\implies{\Longrightarrow}
\def\mapsto{\mapstochar\kern-9mu\rightarrow}