Theorem relen

Description: Equinumerosity is a relation. (Contributed by NM, 28-Mar-1998)

	Ref	Expression
Assertion	relen	$$⊢\mathrm{Rel}\approx$$

Proof

Step	Hyp	Ref	Expression
1		df-en	$$⊢\approx =\left\{⟨x,y⟩|\exists ff:x\underset{1-1\; onto}{⟶}y\right\}$$
2	1	relopabi	$$⊢\mathrm{Rel}\approx$$