# In tensor notation in Spivak's Calculus on Manifolds, what is that character that looks like a 3?

For example, saying that $T$ is a k-tensor one might see $T\in 3^k(V)$, of course it's not actually a 3. It looks somewhat like Fraktur font Z: $\frak{Z}$. I couldn't detexify it, and it doesn't appear to be a standard notation for the set of tensors. Other resources seem to just use $T$.

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As far as I can tell, it's fraktur I: $\mathfrak{I}$. I don't think this is standard.

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I always thought it was a script T, as is used in John Lee's "Introduction to Smooth Manifolds" (though admittedly for tensor fields).

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It doesn't look like \mathfrak{T} or \mathcal{T}. But I guess these things aren't necessarily set in stone. –  Qiaochu Yuan Dec 19 '10 at 6:16
Isn't there a \mathscr font? Maybe it's \mathscr{T}? –  Jesse Madnick Dec 19 '10 at 18:45