# The \not rendering and the line over sigma symbol

I am writing a paper and I need to use the \not command on \sigma which stands for a order relation on a set. The issue is that the line over the sigma symbol is rendered poorly, is there any way I am not aware of so that the exact symbol I need is displayed correctly?

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 Please add a minimal working example (MWE) that illustrates your problem. You can draw it in detexify for both checking the symbol and also having a snapshot of what you wanted to post here. – percusse Nov 10 '12 at 15:25 Crossing out a letter is IMHO a very ugly thing to do. – tohecz Nov 10 '12 at 15:30 @tohecz it's how my professor "named" the order relation, there isn't any I can do about it. – haunted85 Nov 10 '12 at 15:35 @percusse tried to edit the post, but the site throws me back a server error, but I'll keep in mind for next questions I might ask, thank you. – haunted85 Nov 10 '12 at 15:36 – Werner Nov 10 '12 at 15:55

You can use centernot:
\documentclass{article}
$\not\sigma\ \centernot\sigma$