[isabelle-dev] cardinality primitives in Isabelle/HOL?

[Florian Haftmann]

>> Anyway, I am uncertain about the name »poll«.
> 
> From https://en.wikipedia.org/wiki/Cardinality
> 
> "Two sets A and B have the same cardinality if there exists a bijection from A to B, that is, a function from A to B that is both injective and surjective. Such sets are said to be equipotent, equipollent, or equinumerous. This relationship can also be denoted A ≈ B or A ~ B.”

I see.  Using »poll« is a stem, the canonical names would be

	less_eq_poll
	equiv_poll
	greater_eq_poll

(I don't know how useful the strict versions less_poll, greater_poll
would be).

	Florian

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