Metamath Proof Explorer


Theorem 19.29

Description: Theorem 19.29 of Margaris p. 90. See also 19.29r . (Contributed by NM, 21-Jun-1993) (Proof shortened by Andrew Salmon, 13-May-2011)

Ref Expression
Assertion 19.29 xφxψxφψ

Proof

Step Hyp Ref Expression
1 pm3.2 φψφψ
2 1 aleximi xφxψxφψ
3 2 imp xφxψxφψ