Add ≢

[mathcounts4]

"Not equiv" is unicode 8802 = 0x2262 = 0o21142 with corresponding TeX \not\equiv

Can this be added to the list of supported symbols?

[Yolwoocle]

Yes please

[drlippman]

We could add a "looks like" symbol, like !-=, but asciimath doesn't officially handle tex notation. It can handle basic tex like \equiv by just ignoring the backslash and using equiv as the symbol, but that won't work for tex that combines two different commands like \not\equiv. It could handle the single word notequiv, but that's the best that can be done.