Metamath Proof Explorer


Theorem ax1w

Description: Weakening of ax-1 . As a consequence, its associated inference is an instance (where we allow extra hypotheses) of ax-1 . Its commuted form is 2a1 (but ax1w does not require ax-2 ). (Contributed by BJ, 11-Aug-2020)

Ref Expression
Assertion ax1w ( 𝜑 → ( 𝜓 → ( 𝜒𝜓 ) ) )

Proof

Step Hyp Ref Expression
1 ax-1 ( 𝜓 → ( 𝜒𝜓 ) )
2 1 a1i ( 𝜑 → ( 𝜓 → ( 𝜒𝜓 ) ) )