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 𝐵 ⊆ ( 𝐵𝐶 )
3 2 1 sseqtrri 𝐵𝐴