Theorem rexpr 3781

Description: Convert an existential quantification over a pair to a disjunction. (Contributed by NM, 3-Jun-2007.) (Revised by Mario Carneiro, 23-Apr-2015.)

Hypotheses

Ref	Expression
ralpr.1	|- A e. _V
ralpr.2	|- B e. _V
ralpr.3	|- (x = A -> (ph <-> ps))
ralpr.4	|- (x = B -> (ph <-> ch))

Assertion

Ref	Expression
rexpr	|- (E.x e. {A, B}ph <-> (ps \/ ch))

Distinct variable groups:   x,A   x,B   ps,x   ch,x

Allowed substitution hint:   ph(x)

Proof of Theorem rexpr

Step	Hyp	Ref	Expression
1		ralpr.1	. 2 |- A e. _V
2		ralpr.2	. 2 |- B e. _V
3		ralpr.3	. . 3 |- (x = A -> (ph <-> ps))
4		ralpr.4	. . 3 |- (x = B -> (ph <-> ch))
5	3, 4	rexprg 3777	. 2 |- ((A e. _V /\ B e. _V) -> (E.x e. {A, B}ph <-> (ps \/ ch)))
6	1, 2, 5	mp2an 653	1 |- (E.x e. {A, B}ph <-> (ps \/ ch))

Syntax hints:   -> wi 4   <-> wb 176   \/ wo 357   = wceq 1642   e. wcel 1710  E.wrex 2616  _Vcvv 2860  {cpr 3739

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1546  ax-5 1557  ax-17 1616  ax-9 1654  ax-8 1675  ax-6 1729  ax-7 1734  ax-11 1746  ax-12 1925  ax-ext 2334

This theorem depends on definitions:  df-bi 177  df-or 359  df-an 360  df-3an 936  df-nan 1288  df-tru 1319  df-ex 1542  df-nf 1545  df-sb 1649  df-clab 2340  df-cleq 2346  df-clel 2349  df-nfc 2479  df-rex 2621  df-v 2862  df-sbc 3048  df-nin 3212  df-compl 3213  df-un 3215  df-sn 3742  df-pr 3743

This theorem is referenced by: (None)