Theorem rextp 3704

Description: Convert a quantification over a triple to a disjunction. (Contributed by Mario Carneiro, 23-Apr-2015.)

Hypotheses

Ref	Expression
raltp.1	⊢ 𝐴 ∈ V
raltp.2	⊢ 𝐵 ∈ V
raltp.3	⊢ 𝐶 ∈ V
raltp.4	⊢ (𝑥 = 𝐴 → (𝜑 ↔ 𝜓))
raltp.5	⊢ (𝑥 = 𝐵 → (𝜑 ↔ 𝜒))
raltp.6	⊢ (𝑥 = 𝐶 → (𝜑 ↔ 𝜃))

Assertion

Ref	Expression
rextp	⊢ (∃𝑥 ∈ {𝐴, 𝐵, 𝐶}𝜑 ↔ (𝜓 ∨ 𝜒 ∨ 𝜃))

Distinct variable groups:   𝑥,𝐴   𝑥,𝐵   𝑥,𝐶   𝜓,𝑥   𝜒,𝑥   𝜃,𝑥

Allowed substitution hint:   𝜑(𝑥)

Proof of Theorem rextp

Step	Hyp	Ref	Expression
1		raltp.1	. 2 ⊢ 𝐴 ∈ V
2		raltp.2	. 2 ⊢ 𝐵 ∈ V
3		raltp.3	. 2 ⊢ 𝐶 ∈ V
4		raltp.4	. . 3 ⊢ (𝑥 = 𝐴 → (𝜑 ↔ 𝜓))
5		raltp.5	. . 3 ⊢ (𝑥 = 𝐵 → (𝜑 ↔ 𝜒))
6		raltp.6	. . 3 ⊢ (𝑥 = 𝐶 → (𝜑 ↔ 𝜃))
7	4, 5, 6	rextpg 3700	. 2 ⊢ ((𝐴 ∈ V ∧ 𝐵 ∈ V ∧ 𝐶 ∈ V) → (∃𝑥 ∈ {𝐴, 𝐵, 𝐶}𝜑 ↔ (𝜓 ∨ 𝜒 ∨ 𝜃)))
8	1, 2, 3, 7	mp3an 1352	1 ⊢ (∃𝑥 ∈ {𝐴, 𝐵, 𝐶}𝜑 ↔ (𝜓 ∨ 𝜒 ∨ 𝜃))

Syntax hints:   → wi 4   ↔ wb 105   ∨ w3o 982   = wceq 1375   ∈ wcel 2180  ∃wrex 2489  Vcvv 2779  {ctp 3648

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-io 713  ax-5 1473  ax-7 1474  ax-gen 1475  ax-ie1 1519  ax-ie2 1520  ax-8 1530  ax-10 1531  ax-11 1532  ax-i12 1533  ax-bndl 1535  ax-4 1536  ax-17 1552  ax-i9 1556  ax-ial 1560  ax-i5r 1561  ax-ext 2191

This theorem depends on definitions:  df-bi 117  df-3or 984  df-3an 985  df-tru 1378  df-nf 1487  df-sb 1789  df-clab 2196  df-cleq 2202  df-clel 2205  df-nfc 2341  df-rex 2494  df-v 2781  df-sbc 3009  df-un 3181  df-sn 3652  df-pr 3653  df-tp 3654

This theorem is referenced by: (None)