4
Banach-Mazur distance between $P_5$ and $P_3$ is $d(P_5,P_3)=1+\frac{\sqrt5}2$ where $P_n$ is regular polygon in $n$ sides https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=7968198&tag=1.
Shannon zero error capacity of Pentagon is $\sqrt 5$ http://web.cs.elte.hu/~lovasz/scans/theta.pdf.
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Some users use MathJax to get italicized or bold text. This is sometimes done in titles (where MarkDown is not available), but some users do this also in body of a question, where MarkDown is used. They might be simply unaware of MarkDown, but maybe some users prefer how the text looks when Mathj...
