+\def\ave{\mathop{\rm ave}\nolimits} % memory set
+\def\GF{\mathop{\bf GF}\nolimits} % Galois Field
+\def\iff{\Longleftrightarrow}
+
+\newtheorem{theorem}{Theorem}[section]
+\newtheorem{lemma}{Lemma}[theorem]
+\newtheorem{proposition}{Proposition}[theorem]
+\newtheorem{corollary}{Corollary}[theorem]
+
+\newenvironment{definition}[1][Definition]{\begin{trivlist}
+\item[\hskip \labelsep {\bfseries #1}]}{\end{trivlist}}
+