Theorem retbwax4 1480

Description: tbw-ax4 1468 rederived from merco1 1478. (Contributed by Anthony Hart, 17-Sep-2011.) (Proof modification is discouraged.) (New usage is discouraged.)

Assertion

Ref	Expression
retbwax4	|- ( F. -> ph)

Proof of Theorem retbwax4

Step	Hyp	Ref	Expression
1		merco1lem1 1479	. 2 |- (ph -> ( F. -> ph))
2		merco1lem1 1479	. 2 |- ((ph -> ( F. -> ph)) -> ( F. -> ph))
3	1, 2	ax-mp 5	1 |- ( F. -> ph)

This proof depends on syntax axioms:   -> wi 4   F. wfal 1317

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8

This proof depends on definitions:  df-bi 177  df-tru 1319  df-fal 1320

This theorem is used by: (None)