Theorem pm4.24

Description: Theorem *4.24 of WhiteheadRussell p. 117. (Contributed by NM, 11-May-1993)

	Ref	Expression
Assertion	pm4.24	⊢ ( 𝜑 ↔ ( 𝜑 ∧ 𝜑 ) )

Proof

Step	Hyp	Ref	Expression
1		id	⊢ ( 𝜑 → 𝜑 )
2	1	pm4.71i	⊢ ( 𝜑 ↔ ( 𝜑 ∧ 𝜑 ) )