Theorem gencbval 3542

Description: Change of bound variable using implicit substitution. (Contributed by NM, 17-May-1996.)

Hypotheses

Ref	Expression
gencbval.1	⊢ 𝐴 ∈ V
gencbval.2	⊢ (𝐴 = 𝑦 → (𝜑 ↔ 𝜓))
gencbval.3	⊢ (𝐴 = 𝑦 → (𝜒 ↔ 𝜃))
gencbval.4	⊢ (𝜃 ↔ ∃𝑥(𝜒 ∧ 𝐴 = 𝑦))

Assertion

Ref	Expression
gencbval	⊢ (∀𝑥(𝜒 → 𝜑) ↔ ∀𝑦(𝜃 → 𝜓))

Distinct variable groups:   𝜓,𝑥   𝜑,𝑦   𝜃,𝑥   𝜒,𝑦   𝑦,𝐴

Allowed substitution hints:   𝜑(𝑥)   𝜓(𝑦)   𝜒(𝑥)   𝜃(𝑦)   𝐴(𝑥)

Proof of Theorem gencbval

Step	Hyp	Ref	Expression
1		gencbval.1	. . . 4 ⊢ 𝐴 ∈ V
2		gencbval.2	. . . . 5 ⊢ (𝐴 = 𝑦 → (𝜑 ↔ 𝜓))
3	2	notbid 318	. . . 4 ⊢ (𝐴 = 𝑦 → (¬ 𝜑 ↔ ¬ 𝜓))
4		gencbval.3	. . . 4 ⊢ (𝐴 = 𝑦 → (𝜒 ↔ 𝜃))
5		gencbval.4	. . . 4 ⊢ (𝜃 ↔ ∃𝑥(𝜒 ∧ 𝐴 = 𝑦))
6	1, 3, 4, 5	gencbvex 3540	. . 3 ⊢ (∃𝑥(𝜒 ∧ ¬ 𝜑) ↔ ∃𝑦(𝜃 ∧ ¬ 𝜓))
7		exanali 1858	. . 3 ⊢ (∃𝑥(𝜒 ∧ ¬ 𝜑) ↔ ¬ ∀𝑥(𝜒 → 𝜑))
8		exanali 1858	. . 3 ⊢ (∃𝑦(𝜃 ∧ ¬ 𝜓) ↔ ¬ ∀𝑦(𝜃 → 𝜓))
9	6, 7, 8	3bitr3i 301	. 2 ⊢ (¬ ∀𝑥(𝜒 → 𝜑) ↔ ¬ ∀𝑦(𝜃 → 𝜓))
10	9	con4bii 321	1 ⊢ (∀𝑥(𝜒 → 𝜑) ↔ ∀𝑦(𝜃 → 𝜓))

Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 206   ∧ wa 395  ∀wal 1537   = wceq 1539  ∃wex 1778   ∈ wcel 2107  Vcvv 3479

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1794  ax-4 1808  ax-5 1909  ax-6 1966  ax-7 2006  ax-8 2109  ax-9 2117  ax-11 2156  ax-ext 2707

This theorem depends on definitions:  df-bi 207  df-an 396  df-ex 1779  df-cleq 2728  df-clel 2815

This theorem is referenced by: (None)