Theorem kardex

Description: The collection of all sets equinumerous to a set A and having the least possible rank is a set. This is the part of the justification of the definition of kard of Enderton p. 222. (Contributed by NM, 14-Dec-2003) Use the Scott operation. (Revised by BTernaryTau, 19-Jul-2026)

	Ref	Expression
Assertion	kardex	$$⊢Scott\left\{x|x\approx A\right\}\in \mathrm{V}$$

Proof

Step	Hyp	Ref	Expression
1		scottex	$$⊢Scott\left\{x|x\approx A\right\}\in \mathrm{V}$$