Metamath Proof Explorer


Theorem uni0OLD

Description: Obsolete version of uni0 as of 1-Feb-2026. (Contributed by NM, 16-Sep-1993) Remove use of ax-nul . (Revised by Eric Schmidt, 4-Apr-2007) (Proof modification is discouraged.) (New usage is discouraged.)

Ref Expression
Assertion uni0OLD
|- U. (/) = (/)

Proof

Step Hyp Ref Expression
1 0ss
 |-  (/) C_ { (/) }
2 uni0b
 |-  ( U. (/) = (/) <-> (/) C_ { (/) } )
3 1 2 mpbir
 |-  U. (/) = (/)