Theorem 19.28OLD 2235

Description: Obsolete proof of 19.28 2096 as of 6-Oct-2021. (Contributed by NM, 1-Aug-1993.) (Proof modification is discouraged.) (New usage is discouraged.)

Hypothesis

Ref	Expression
19.28OLD.1	|- F/ x ph

Assertion

Ref	Expression
19.28OLD	|- ( A. x ( ph /\ ps ) <-> ( ph /\ A. x ps ) )

Proof of Theorem 19.28OLD

Step	Hyp	Ref	Expression
1		19.26 1798	. 2 |- ( A. x ( ph /\ ps ) <-> ( A. x ph /\ A. x ps ) )
2		19.28OLD.1	. . . 4 |- F/ x ph
3	2	19.3OLD 2202	. . 3 |- ( A. x ph <-> ph )
4	3	anbi1i 731	. 2 |- ( ( A. x ph /\ A. x ps ) <-> ( ph /\ A. x ps ) )
5	1, 4	bitri 264	1 |- ( A. x ( ph /\ ps ) <-> ( ph /\ A. x ps ) )

Syntax hints:   <-> wb 196   /\ wa 384   A.wal 1481   F/wnfOLD 1709

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1722  ax-4 1737  ax-5 1839  ax-6 1888  ax-7 1935  ax-12 2047

This theorem depends on definitions:  df-bi 197  df-an 386  df-ex 1705  df-nfOLD 1721

This theorem is referenced by:  nfan1OLD  2236