Theorem unv 3971

Description: The union of a class with the universal class is the universal class. Exercise 4.10(l) of [Mendelson] p. 231. (Contributed by NM, 17-May-1998.)

Assertion

Ref	Expression
unv	|- ( A u. _V ) = _V

Proof of Theorem unv

Step	Hyp	Ref	Expression
1		ssv 3625	. 2 |- ( A u. _V ) C_ _V
2		ssun2 3777	. 2 |- _V C_ ( A u. _V )
3	1, 2	eqssi 3619	1 |- ( A u. _V ) = _V

Syntax hints:   = wceq 1483   _Vcvv 3200   u. cun 3572

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1722  ax-4 1737  ax-5 1839  ax-6 1888  ax-7 1935  ax-9 1999  ax-10 2019  ax-11 2034  ax-12 2047  ax-13 2246  ax-ext 2602

This theorem depends on definitions:  df-bi 197  df-or 385  df-an 386  df-tru 1486  df-ex 1705  df-nf 1710  df-sb 1881  df-clab 2609  df-cleq 2615  df-clel 2618  df-nfc 2753  df-v 3202  df-un 3579  df-in 3581  df-ss 3588

This theorem is referenced by:  oev2  7603