deletions | additions       diff --git a/header.tex b/header.tex  index b22e9e8..d90a466 100644  --- a/header.tex  +++ b/header.tex 
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%% \def\me#1#2#3{\bra{#1} #2 \ket{#3}}  %% \def\olap#1#2{\bra{#1} #2 \rangle}  %% \def\avg#1{\langle #1 \rangle}  %% \DeclareMathOperator{\sgn}{sgn} \DeclareMathOperator{\tr}{tr}