Metamath Proof Explorer


Theorem syl9

Description: A nested syllogism inference with different antecedents. (Contributed by NM, 13-May-1993) (Proof shortened by Josh Purinton, 29-Dec-2000)

Ref Expression
Hypotheses syl9.1
|- ( ph -> ( ps -> ch ) )
syl9.2
|- ( th -> ( ch -> ta ) )
Assertion syl9
|- ( ph -> ( th -> ( ps -> ta ) ) )

Proof

Step Hyp Ref Expression
1 syl9.1
 |-  ( ph -> ( ps -> ch ) )
2 syl9.2
 |-  ( th -> ( ch -> ta ) )
3 2 a1i
 |-  ( ph -> ( th -> ( ch -> ta ) ) )
4 1 3 syl5d
 |-  ( ph -> ( th -> ( ps -> ta ) ) )