Theorem e220 40977

Description: A virtual deduction elimination rule. (Contributed by Alan Sare, 24-Jun-2011.) (Proof modification is discouraged.) (New usage is discouraged.)

Hypotheses

Ref	Expression
e220.1	⊢ (   𝜑   ,   𝜓   ▶   𝜒   )
e220.2	⊢ (   𝜑   ,   𝜓   ▶   𝜃   )
e220.3	⊢ 𝜏
e220.4	⊢ (𝜒 → (𝜃 → (𝜏 → 𝜂)))

Assertion

Ref	Expression
e220	⊢ (   𝜑   ,   𝜓   ▶   𝜂   )

Proof of Theorem e220

Step	Hyp	Ref	Expression
1		e220.1	. 2 ⊢ (   𝜑   ,   𝜓   ▶   𝜒   )
2		e220.2	. 2 ⊢ (   𝜑   ,   𝜓   ▶   𝜃   )
3		e220.3	. . 3 ⊢ 𝜏
4	3	vd02 40938	. 2 ⊢ (   𝜑   ,   𝜓   ▶   𝜏   )
5		e220.4	. 2 ⊢ (𝜒 → (𝜃 → (𝜏 → 𝜂)))
6	1, 2, 4, 5	e222 40976	1 ⊢ (   𝜑   ,   𝜓   ▶   𝜂   )

Syntax hints:   → wi 4  (   wvd2 40917

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8

This theorem depends on definitions:  df-bi 209  df-an 399  df-vd2 40918

This theorem is referenced by:  e120  41003