Theorem bj-sbimedh 12967

Description: A strengthening of sbiedh 1760 (same proof). (Contributed by BJ, 16-Dec-2019.)

Hypotheses

Ref	Expression
bj-sbimedh.1	⊢ (𝜑 → ∀𝑥𝜑)
bj-sbimedh.2	⊢ (𝜑 → (𝜒 → ∀𝑥𝜒))
bj-sbimedh.3	⊢ (𝜑 → (𝑥 = 𝑦 → (𝜓 → 𝜒)))

Assertion

Ref	Expression
bj-sbimedh	⊢ (𝜑 → ([𝑦 / 𝑥]𝜓 → 𝜒))

Proof of Theorem bj-sbimedh

Step	Hyp	Ref	Expression
1		sb1 1739	. . 3 ⊢ ([𝑦 / 𝑥]𝜓 → ∃𝑥(𝑥 = 𝑦 ∧ 𝜓))
2		bj-sbimedh.1	. . . 4 ⊢ (𝜑 → ∀𝑥𝜑)
3		bj-sbimedh.3	. . . . 5 ⊢ (𝜑 → (𝑥 = 𝑦 → (𝜓 → 𝜒)))
4	3	impd 252	. . . 4 ⊢ (𝜑 → ((𝑥 = 𝑦 ∧ 𝜓) → 𝜒))
5	2, 4	eximdh 1590	. . 3 ⊢ (𝜑 → (∃𝑥(𝑥 = 𝑦 ∧ 𝜓) → ∃𝑥𝜒))
6	1, 5	syl5 32	. 2 ⊢ (𝜑 → ([𝑦 / 𝑥]𝜓 → ∃𝑥𝜒))
7		bj-sbimedh.2	. . 3 ⊢ (𝜑 → (𝜒 → ∀𝑥𝜒))
8	2, 7	19.9hd 1640	. 2 ⊢ (𝜑 → (∃𝑥𝜒 → 𝜒))
9	6, 8	syld 45	1 ⊢ (𝜑 → ([𝑦 / 𝑥]𝜓 → 𝜒))

Syntax hints:   → wi 4   ∧ wa 103  ∀wal 1329  ∃wex 1468  [wsb 1735

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-5 1423  ax-gen 1425  ax-ie1 1469  ax-ie2 1470  ax-4 1487  ax-ial 1514

This theorem depends on definitions:  df-bi 116  df-sb 1736

This theorem is referenced by:  bj-sbimeh  12968