Theorem axun2 4434

Description: A variant of the Axiom of Union ax-un 4432. For any set x, there exists a set y whose members are exactly the members of the members of x i.e. the union of x. Axiom Union of [BellMachover] p. 466. (Contributed by NM, 4-Jun-2006.)

Assertion

Ref	Expression
axun2	|- E. y A. z ( z e. y <-> E. w ( z e. w /\ w e. x ) )

Distinct variable group:   x, w, y, z

Proof of Theorem axun2

Step	Hyp	Ref	Expression
1		ax-un 4432	. 2 |- E. y A. z ( E. w ( z e. w /\ w e. x ) -> z e. y )
2	1	bm1.3ii 4123	1 |- E. y A. z ( z e. y <-> E. w ( z e. w /\ w e. x ) )

Syntax hints:   /\ wa 104   <-> wb 105   A.wal 1351   E.wex 1492

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-5 1447  ax-7 1448  ax-gen 1449  ax-ie1 1493  ax-ie2 1494  ax-8 1504  ax-4 1510  ax-17 1526  ax-i9 1530  ax-ial 1534  ax-14 2151  ax-sep 4120  ax-un 4432

This theorem depends on definitions:  df-bi 117

This theorem is referenced by: (None)