In the mathematical field of knot theory, the crosscap number of a knot K is the minimum of
taken over all compact, connected, non-orientable surfaces S bounding K; here is the Euler characteristic. The crosscap number of the unknot is zero, as the Euler characteristic of the disk is one.
Read more about Crosscap Number: Examples
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“The world is so full of a number of things,
I’m sure we should all be as happy as kings.”
—Robert Louis Stevenson (1850–1894)