Theorem exlimd2 1609

Description: Deduction from Theorem 19.23 of [Margaris] p. 90. Similar to exlimdh 1610 but with one slightly different hypothesis. (Contributed by Jim Kingdon, 30-Dec-2017.)

Hypotheses

Ref	Expression
exlimd2.1	⊢ (𝜑 → ∀𝑥𝜑)
exlimd2.2	⊢ (𝜑 → (𝜒 → ∀𝑥𝜒))
exlimd2.3	⊢ (𝜑 → (𝜓 → 𝜒))

Assertion

Ref	Expression
exlimd2	⊢ (𝜑 → (∃𝑥𝜓 → 𝜒))

Proof of Theorem exlimd2

Step	Hyp	Ref	Expression
1		exlimd2.1	. . 3 ⊢ (𝜑 → ∀𝑥𝜑)
2		exlimd2.2	. . 3 ⊢ (𝜑 → (𝜒 → ∀𝑥𝜒))
3	1, 2	alrimih 1483	. 2 ⊢ (𝜑 → ∀𝑥(𝜒 → ∀𝑥𝜒))
4		exlimd2.3	. . 3 ⊢ (𝜑 → (𝜓 → 𝜒))
5	1, 4	alrimih 1483	. 2 ⊢ (𝜑 → ∀𝑥(𝜓 → 𝜒))
6		19.23ht 1511	. . 3 ⊢ (∀𝑥(𝜒 → ∀𝑥𝜒) → (∀𝑥(𝜓 → 𝜒) ↔ (∃𝑥𝜓 → 𝜒)))
7	6	biimpd 144	. 2 ⊢ (∀𝑥(𝜒 → ∀𝑥𝜒) → (∀𝑥(𝜓 → 𝜒) → (∃𝑥𝜓 → 𝜒)))
8	3, 5, 7	sylc 62	1 ⊢ (𝜑 → (∃𝑥𝜓 → 𝜒))

Syntax hints:   → wi 4  ∀wal 1362  ∃wex 1506

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-5 1461  ax-gen 1463  ax-ie2 1508

This theorem depends on definitions:  df-bi 117

This theorem is referenced by:  equsexd  1743  cbvexdh  1941