Theorem exnal 721

Description: Theorem 19.14 of [Margaris] p. 90.

Assertion

Ref	Expression
exnal	|- (E.x -. ph <-> -. A.xph)

Proof of Theorem exnal

Step	Hyp	Ref	Expression
1		alex 717	. 2 |- (A.xph <-> -. E.x -. ph)
2	1	bicon2i 194	1 |- (E.x -. ph <-> -. A.xph)

Syntax hints:  -. wn 1   <-> wb 127  A.wal 672  E.wex 678

This theorem is referenced by:  alexn 726  19.29 752  eqsex 834  cla42gv 1399  nss 1550  nssss 1866  dtru 1889  intirr 2628  zfcndpow 3762

This theorem was proved from axioms:  ax-1 3  ax-2 4  ax-3 5  ax-mp 6  ax-4 673  ax-5 674  ax-gen 677

This theorem depends on definitions:  df-bi 128  df-an 198  df-ex 679

metamath.org