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Metamath Proof Explorer


Theorem anclb

Description: Conjoin antecedent to left of consequent. Theorem *4.7 of WhiteheadRussell p. 120. (Contributed by NM, 25-Jul-1999) (Proof shortened by Wolf Lammen, 24-Mar-2013)

Ref Expression
Assertion anclb ( ( 𝜑𝜓 ) ↔ ( 𝜑 → ( 𝜑𝜓 ) ) )

Proof

Step Hyp Ref Expression
1 ibar ( 𝜑 → ( 𝜓 ↔ ( 𝜑𝜓 ) ) )
2 1 pm5.74i ( ( 𝜑𝜓 ) ↔ ( 𝜑 → ( 𝜑𝜓 ) ) )