Theorem sylsyld 58

Description: A double syllogism inference. (Contributed by Alan Sare, 20-Apr-2011.)

Hypotheses

Ref	Expression
sylsyld.1	|- ( ph -> ps )
sylsyld.2	|- ( ph -> ( ch -> th ) )
sylsyld.3	|- ( ps -> ( th -> ta ) )

Assertion

Ref	Expression
sylsyld	|- ( ph -> ( ch -> ta ) )

Proof of Theorem sylsyld

Step	Hyp	Ref	Expression
1		sylsyld.2	. 2 |- ( ph -> ( ch -> th ) )
2		sylsyld.1	. . 3 |- ( ph -> ps )
3		sylsyld.3	. . 3 |- ( ps -> ( th -> ta ) )
4	2, 3	syl 14	. 2 |- ( ph -> ( th -> ta ) )
5	1, 4	syld 45	1 |- ( ph -> ( ch -> ta ) )

This proof depends on syntax axioms:   -> wi 4

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

This theorem is used by:  ax10o  1767  a16g  1917  rspc2vd  3216  trintssm  4247  funimaexglem  5467  smoiun  6576  en2  7116  findcard2  7197  ctssdc  7459  mkvprop  7504  ltexprlemrl  7983  archsr  8155  elfz0ubfz0  10549  ctinf  13379  wlkres  16825