Metamath Proof Explorer


Theorem tb-ax2

Description: The second of three axioms in the Tarski-Bernays axiom system. (Contributed by Anthony Hart, 16-Aug-2011) (Proof modification is discouraged.) (New usage is discouraged.)

Ref Expression
Assertion tb-ax2
|- ( ph -> ( ps -> ph ) )

Proof

Step Hyp Ref Expression
1 ax-1
 |-  ( ph -> ( ps -> ph ) )