Theorem a1d

Description: Deduction introducing an embedded antecedent. Deduction form of ax-1 and a1i . (Contributed by NM, 5-Jan-1993) (Proof shortened by Stefan Allan, 20-Mar-2006)

	Ref	Expression
Hypothesis	a1d.1	⊢ ( 𝜑 → 𝜓 )
Assertion	a1d	⊢ ( 𝜑 → ( 𝜒 → 𝜓 ) )

Proof

Step	Hyp	Ref	Expression
1		a1d.1	⊢ ( 𝜑 → 𝜓 )
2		ax-1	⊢ ( 𝜓 → ( 𝜒 → 𝜓 ) )
3	1 2	syl	⊢ ( 𝜑 → ( 𝜒 → 𝜓 ) )