Theorem vtocl2 3561

Description: Implicit substitution of classes for setvar variables. (Contributed by NM, 26-Jul-1995.) (Proof shortened by Andrew Salmon, 8-Jun-2011.)

Hypotheses

Ref	Expression
vtocl2.1	⊢ 𝐴 ∈ V
vtocl2.2	⊢ 𝐵 ∈ V
vtocl2.3	⊢ ((𝑥 = 𝐴 ∧ 𝑦 = 𝐵) → (𝜑 ↔ 𝜓))
vtocl2.4	⊢ 𝜑

Assertion

Ref	Expression
vtocl2	⊢ 𝜓

Distinct variable groups:   𝑥,𝑦,𝐴   𝑥,𝐵,𝑦   𝜓,𝑥,𝑦

Allowed substitution hints:   𝜑(𝑥,𝑦)

Proof of Theorem vtocl2

Step	Hyp	Ref	Expression
1		vtocl2.2	. 2 ⊢ 𝐵 ∈ V
2		vtocl2.4	. . . 4 ⊢ 𝜑
3	2	a1i 11	. . 3 ⊢ (𝑦 = 𝐵 → 𝜑)
4		vtocl2.1	. . . 4 ⊢ 𝐴 ∈ V
5		vtocl2.3	. . . . 5 ⊢ ((𝑥 = 𝐴 ∧ 𝑦 = 𝐵) → (𝜑 ↔ 𝜓))
6	5	pm5.74da 802	. . . 4 ⊢ (𝑥 = 𝐴 → ((𝑦 = 𝐵 → 𝜑) ↔ (𝑦 = 𝐵 → 𝜓)))
7	4, 6, 3	vtocl 3559	. . 3 ⊢ (𝑦 = 𝐵 → 𝜓)
8	3, 7	2thd 267	. 2 ⊢ (𝑦 = 𝐵 → (𝜑 ↔ 𝜓))
9	1, 8, 2	vtocl 3559	1 ⊢ 𝜓

Syntax hints:   → wi 4   ↔ wb 208   ∧ wa 398   = wceq 1537   ∈ wcel 2114  Vcvv 3494

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1796  ax-4 1810  ax-5 1911  ax-6 1970  ax-7 2015  ax-8 2116  ax-9 2124  ax-ext 2793

This theorem depends on definitions:  df-bi 209  df-an 399  df-ex 1781  df-cleq 2814  df-clel 2893

This theorem is referenced by:  vtocl3  3563  caovord  7359  sornom  9699  wloglei  11172  ipodrsima  17775  mpfind  20320  mclsppslem  32830  monotoddzzfi  39559