deletions | additions       diff --git a/Old QFT.tex b/Old QFT.tex  index 3614e7e..1e46e79 100644  --- a/Old QFT.tex  +++ b/Old QFT.tex 
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Some relationships \begin{equation}  [a,a^+,1]=2aa^+-aa^+-a^+a=[a,a^+] \\  [a^+,a,1]=2a^+a-a^+a-aa^+ [a^+,a,1]=2a^+a-a^+a-aa^+=[a^+,a]  \\ \end{equation}