Metamath Proof Explorer


Theorem bnj931

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

Ref Expression
Hypothesis bnj931.1 A=BC
Assertion bnj931 BA

Proof

Step Hyp Ref Expression
1 bnj931.1 A=BC
2 ssun1 BBC
3 2 1 sseqtrri BA