Theorem 3bitr2d

Description: Deduction from transitivity of biconditional. (Contributed by NM, 4-Aug-2006)

	Ref	Expression
Hypotheses	3bitr2d.1	⊢ ( 𝜑 → ( 𝜓 ↔ 𝜒 ) )
	3bitr2d.2	⊢ ( 𝜑 → ( 𝜃 ↔ 𝜒 ) )
	3bitr2d.3	⊢ ( 𝜑 → ( 𝜃 ↔ 𝜏 ) )
Assertion	3bitr2d	⊢ ( 𝜑 → ( 𝜓 ↔ 𝜏 ) )

Proof

Step	Hyp	Ref	Expression
1		3bitr2d.1	⊢ ( 𝜑 → ( 𝜓 ↔ 𝜒 ) )
2		3bitr2d.2	⊢ ( 𝜑 → ( 𝜃 ↔ 𝜒 ) )
3		3bitr2d.3	⊢ ( 𝜑 → ( 𝜃 ↔ 𝜏 ) )
4	1 2	bitr4d	⊢ ( 𝜑 → ( 𝜓 ↔ 𝜃 ) )
5	4 3	bitrd	⊢ ( 𝜑 → ( 𝜓 ↔ 𝜏 ) )