Metamath Proof Explorer

Theorem tsor3

Description: A Tseitin axiom for logical disjunction, in deduction form. (Contributed by Giovanni Mascellani, 25-Mar-2018)

Ref Expression
Assertion tsor3 
|- ( th -> ( -. ps \/ ( ph \/ ps ) ) )

Proof

Step Hyp Ref Expression
1 olc 
 |-  ( ps -> ( ph \/ ps ) )
2 1 imori 
 |-  ( -. ps \/ ( ph \/ ps ) )
3 2 a1i 
 |-  ( th -> ( -. ps \/ ( ph \/ ps ) ) )