Theorem unv 1724

Description: The union of a class with the universal class is the universal class. Exercise 4.10(l) of [Mendelson] p. 231.

Assertion

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

Proof of Theorem unv

Step	Hyp	Ref	Expression
1		ssv 1520	. 2 |- (A u. V) (_ V
2		ssun2 1622	. 2 |- V (_ (A u. V)
3	1, 2	eqssi 1517	1 |- (A u. V) = V

Syntax hints:   = wceq 1091  Vcvv 1348   u. cun 1485

This theorem was proved from axioms:  ax-1 3  ax-2 4  ax-3 5  ax-mp 6  ax-4 673  ax-5 674  ax-6 675  ax-7 676  ax-gen 677  ax-8 798  ax-9 799  ax-10 800  ax-11 801  ax-12 802  ax-16 922  ax-17 925  ax-ext 1074

This theorem depends on definitions:  df-bi 128  df-or 197  df-an 198  df-ex 679  df-sb 853  df-clab 1093  df-cleq 1097  df-clel 1099  df-v 1349  df-un 1490  df-in 1491  df-ss 1492

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