Metamath Proof Explorer

Theorem bnj1293

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

Ref Expression
Hypothesis bnj1293.1 
|- A = ( B i^i C )
Assertion bnj1293 
|- A C_ C

Proof

Step Hyp Ref Expression
1 bnj1293.1 
 |-  A = ( B i^i C )
2 inss2 
 |-  ( B i^i C ) C_ C
3 1 2 eqsstri 
 |-  A C_ C