Set cardinality

Set

context $X$ … set
definiendum $ \left|X\right|\equiv\mathrm{inf}\{\alpha\ |\ \alpha\in\mathrm{Ord}\ \land\ \alpha\approx X\} $

Discussion

Reference

Wikipedia: Cardinal numbers, Cardinal assignment, Von Neumann cardinal assignment

Parents

Context

Non-strict partial order, Bijective function

Element of

Ordinal number