Metamath Proof Explorer

Theorem bnj1292

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

Ref Expression
Hypothesis bnj1292.1 
|- A = ( B i^i C )
Assertion bnj1292 
|- A C_ B

Proof

Step Hyp Ref Expression
1 bnj1292.1 
 |-  A = ( B i^i C )
2 inss1 
 |-  ( B i^i C ) C_ B
3 1 2 eqsstri 
 |-  A C_ B