Theorem equidqe 1480

Description: equid 1645 with some quantification and negation without using ax-4 1455 or ax-17 1474. (Contributed by NM, 13-Jan-2011.) (Proof shortened by Wolf Lammen, 27-Feb-2014.)

Assertion

Ref	Expression
equidqe	|- -. A. y -. x = x

Proof of Theorem equidqe

Step	Hyp	Ref	Expression
1		ax-9 1479	. 2 |- -. A. y -. y = x
2		ax-8 1450	. . . . 5 |- ( y = x -> ( y = x -> x = x ) )
3	2	pm2.43i 49	. . . 4 |- ( y = x -> x = x )
4	3	con3i 602	. . 3 |- ( -. x = x -> -. y = x )
5	4	alimi 1399	. 2 |- ( A. y -. x = x -> A. y -. y = x )
6	1, 5	mto 629	1 |- -. A. y -. x = x

Syntax hints:   -. wn 3   A.wal 1297

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-in1 584  ax-in2 585  ax-5 1391  ax-gen 1393  ax-ie2 1438  ax-8 1450  ax-i9 1478

This theorem depends on definitions:  df-bi 116  df-tru 1302  df-fal 1305

This theorem is referenced by:  ax4sp1  1481