Theorem dfifp4

Description: Alternate definition of the conditional operator for propositions. (Contributed by BJ, 30-Sep-2019)

	Ref	Expression
Assertion	dfifp4	⊢ ( if- ( 𝜑 , 𝜓 , 𝜒 ) ↔ ( ( ¬ 𝜑 ∨ 𝜓 ) ∧ ( 𝜑 ∨ 𝜒 ) ) )

Proof

Step	Hyp	Ref	Expression
1		dfifp3	⊢ ( if- ( 𝜑 , 𝜓 , 𝜒 ) ↔ ( ( 𝜑 → 𝜓 ) ∧ ( 𝜑 ∨ 𝜒 ) ) )
2		imor	⊢ ( ( 𝜑 → 𝜓 ) ↔ ( ¬ 𝜑 ∨ 𝜓 ) )
3	1 2	bianbi	⊢ ( if- ( 𝜑 , 𝜓 , 𝜒 ) ↔ ( ( ¬ 𝜑 ∨ 𝜓 ) ∧ ( 𝜑 ∨ 𝜒 ) ) )