Metamath Proof Explorer


Theorem intssuni2

Description: Subclass relationship for intersection and union. (Contributed by NM, 29-Jul-2006)

Ref Expression
Assertion intssuni2 ABAAB

Proof

Step Hyp Ref Expression
1 intssuni AAA
2 uniss ABAB
3 1 2 sylan9ssr ABAAB