Theorem r19.2m 3578

Description: Theorem 19.2 of [Margaris] p. 89 with restricted quantifiers (compare 19.2 1684). The restricted version is valid only when the domain of quantification is inhabited. (Contributed by Jim Kingdon, 5-Aug-2018.) (Revised by Jim Kingdon, 7-Apr-2023.)

Assertion

Ref	Expression
r19.2m	|- ( ( E. y y e. A /\ A. x e. A ph ) -> E. x e. A ph )

Distinct variable groups:   x, A   y, A

Allowed substitution hints:   ph( x, y)

Proof of Theorem r19.2m

Dummy variable z is distinct from all other variables.

Step	Hyp	Ref	Expression
1		eleq1w 2290	. . . 4 |- ( x = z -> ( x e. A <-> z e. A ) )
2	1	cbvexv 1965	. . 3 |- ( E. x x e. A <-> E. z z e. A )
3		eleq1w 2290	. . . 4 |- ( z = y -> ( z e. A <-> y e. A ) )
4	3	cbvexv 1965	. . 3 |- ( E. z z e. A <-> E. y y e. A )
5	2, 4	bitri 184	. 2 |- ( E. x x e. A <-> E. y y e. A )
6		df-ral 2513	. . . . 5 |- ( A. x e. A ph <-> A. x ( x e. A -> ph ) )
7		exintr 1680	. . . . 5 |- ( A. x ( x e. A -> ph ) -> ( E. x x e. A -> E. x ( x e. A /\ ph ) ) )
8	6, 7	sylbi 121	. . . 4 |- ( A. x e. A ph -> ( E. x x e. A -> E. x ( x e. A /\ ph ) ) )
9		df-rex 2514	. . . 4 |- ( E. x e. A ph <-> E. x ( x e. A /\ ph ) )
10	8, 9	imbitrrdi 162	. . 3 |- ( A. x e. A ph -> ( E. x x e. A -> E. x e. A ph ) )
11	10	impcom 125	. 2 |- ( ( E. x x e. A /\ A. x e. A ph ) -> E. x e. A ph )
12	5, 11	sylanbr 285	1 |- ( ( E. y y e. A /\ A. x e. A ph ) -> E. x e. A ph )

Syntax hints:   -> wi 4   /\ wa 104   A.wal 1393   E.wex 1538   e. wcel 2200   A.wral 2508   E.wrex 2509

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 1493  ax-7 1494  ax-gen 1495  ax-ie1 1539  ax-ie2 1540  ax-8 1550  ax-4 1556  ax-17 1572  ax-i9 1576  ax-ial 1580

This theorem depends on definitions:  df-bi 117  df-clel 2225  df-ral 2513  df-rex 2514

This theorem is referenced by:  intssunim  3945  riinm  4038  iinexgm  4238  xpiindim  4859  cnviinm  5270  eusvobj2  5987  iinerm  6754  suplocexprlemml  7903  rexfiuz  11500  r19.2uz  11504  climuni  11804  pc2dvds  12853  issubg4m  13730  cncnp2m  14905