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Theorem sylcom 25
Description: Syllogism inference with commutation of antecedents. (Contributed by NM, 29-Aug-2004.) (Proof shortened by O'Cat, 2-Feb-2006.) (Proof shortened by Stefan Allan, 23-Feb-2006.)
Hypotheses
Ref Expression
sylcom.1 (φ → (ψχ))
sylcom.2 (ψ → (χθ))
Assertion
Ref Expression
sylcom (φ → (ψθ))

Proof of Theorem sylcom
StepHypRef Expression
1 sylcom.1 . 2 (φ → (ψχ))
2 sylcom.2 . . 3 (ψ → (χθ))
32a2i 12 . 2 ((ψχ) → (ψθ))
41, 3syl 15 1 (φ → (ψθ))
Colors of variables: wff setvar class
Syntax hints:  wi 4
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7
This theorem is referenced by:  syl5com  26  syl6  29  syli  33  mpbidi  207
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