Metamath Proof Explorer


Theorem bnj1422

Description: First-order logic and set theory. (Contributed by Jonathan Ben-Naim, 3-Jun-2011) (New usage is discouraged.)

Ref Expression
Hypotheses bnj1422.1 φ Fun A
bnj1422.2 φ dom A = B
Assertion bnj1422 φ A Fn B

Proof

Step Hyp Ref Expression
1 bnj1422.1 φ Fun A
2 bnj1422.2 φ dom A = B
3 df-fn A Fn B Fun A dom A = B
4 1 2 3 sylanbrc φ A Fn B