Theorem abn0m 3314

Description: Inhabited class abstraction. (Contributed by Jim Kingdon, 8-Jul-2022.)

Assertion

Ref	Expression
abn0m	|- ( E. y y e. { x | ph } <-> E. x ph )

Distinct variable groups:   ph, y   x, y

Allowed substitution hint:   ph( x)

Proof of Theorem abn0m

Step	Hyp	Ref	Expression
1		nfv 1467	. . 3 |- F/ y x e. { x | ph }
2		nfsab1 2079	. . 3 |- F/ x y e. { x | ph }
3		eleq1w 2149	. . 3 |- ( x = y -> ( x e. { x | ph } <-> y e. { x | ph } ) )
4	1, 2, 3	cbvex 1687	. 2 |- ( E. x x e. { x | ph } <-> E. y y e. { x | ph } )
5		abid 2077	. . 3 |- ( x e. { x | ph } <-> ph )
6	5	exbii 1542	. 2 |- ( E. x x e. { x | ph } <-> E. x ph )
7	4, 6	bitr3i 185	1 |- ( E. y y e. { x | ph } <-> E. x ph )

Syntax hints:   <-> wb 104   E.wex 1427   e. wcel 1439   {cab 2075

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-5 1382  ax-7 1383  ax-gen 1384  ax-ie1 1428  ax-ie2 1429  ax-8 1441  ax-11 1443  ax-4 1446  ax-17 1465  ax-i9 1469  ax-ial 1473

This theorem depends on definitions:  df-bi 116  df-nf 1396  df-sb 1694  df-clab 2076  df-clel 2085

This theorem is referenced by:  mapprc  6425