# Srednicki 43.10

by Lapidus
Tags: 4310, srednicki
 P: 185 i'll take a shot. let me argue by analogy, maybe making the rule plausible. suppose i have anticommuting numbers x,y,h. and i'm given the expression yx and i want to differentiate it with respect to x. lacking any better choice i form the difference quotient $$\frac{d}{dx}(yx) = \lim_{h \rightarrow 0} \frac{1}{h} ( y(x+h) - yx )$$ $$= \lim_{h \rightarrow 0} \frac{1}{h} yh$$ now because the numbers are anticommuting i can't just cancel h. i have to first swap yh or h^(-1) and y and then i can cancel. $$= \lim_{h \rightarrow 0}\left( -y \frac{1}{h} h \right)= -y$$