Theorem 19.27 1923

Description: Theorem 19.27 of [Margaris] p. 90. See 19.27v 1766 for a version requiring fewer axioms. (Contributed by NM, 21-Jun-1993.)

Hypothesis

Ref	Expression
19.27.1

Assertion

Ref	Expression
19.27

Proof of Theorem 19.27

Step	Hyp	Ref	Expression
1		19.26 1680	. 2
2		19.27.1	. . . 4
3	2	19.3 1888	. . 3
4	3	anbi2i 694	. 2
5	1, 4	bitri 249	1

Syntax hints:  <->wb 184  /\wa 369  A.wal 1393  F/wnf 1616

This theorem is referenced by:  aaan  1975

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1618  ax-4 1631  ax-5 1704  ax-6 1747  ax-7 1790  ax-12 1854

This theorem depends on definitions:  df-bi 185  df-an 371  df-ex 1613  df-nf 1617