The least used letters on ArXiv (source: <gwern.net/Variables>)
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Pro tip: the best use of \Xi is for complex variables, that way you can get expressions like $\frac{\Xi}{\overline{\Xi}}$.

Jun 4, 2021 · 5:06 PM UTC

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Also, oops-ilon
Eric Neyman @ericneyman
5 Mar 2021
Starting a new trend: using υ to denote the error term. The letter's badly neglected, *and* its pronounced "oops-ilon".
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