Theorem iunconst 4529

Description: Indexed union of a constant class, i.e. where B does not depend on x. (Contributed by NM, 5-Sep-2004.) (Proof shortened by Andrew Salmon, 25-Jul-2011.)

Assertion

Ref	Expression
iunconst	|- ( A =/= (/) -> U_ x e. A B = B )

Distinct variable groups:   x, A   x, B

Proof of Theorem iunconst

Dummy variable y is distinct from all other variables.

Step	Hyp	Ref	Expression
1		r19.9rzv 4065	. . 3 |- ( A =/= (/) -> ( y e. B <-> E. x e. A y e. B ) )
2		eliun 4524	. . 3 |- ( y e. U_ x e. A B <-> E. x e. A y e. B )
3	1, 2	syl6rbbr 279	. 2 |- ( A =/= (/) -> ( y e. U_ x e. A B <-> y e. B ) )
4	3	eqrdv 2620	1 |- ( A =/= (/) -> U_ x e. A B = B )

Syntax hints:   -> wi 4   = wceq 1483   e. wcel 1990   =/= wne 2794   E.wrex 2913   (/)c0 3915   U_ciun 4520

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-ne 2795  df-ral 2917  df-rex 2918  df-v 3202  df-dif 3577  df-nul 3916  df-iun 4522

This theorem is referenced by:  iununi  4610  oe1m  7625  oarec  7642  oelim2  7675  bnj1143  30861  poimirlem32  33441  mblfinlem2  33447  hoicvr  40762  ovnlecvr2  40824  iunhoiioo  40890