Theorem prssbd 32857

Description: If a pair is a subset of a class, the second element of the pair is an element of that class. (Contributed by Thierry Arnoux, 2-Nov-2025.)

Hypotheses

Ref	Expression
prssbd.1	⊢ (𝜑 → 𝐵 ∈ 𝑉)
prssbd.2	⊢ (𝜑 → {𝐴, 𝐵} ⊆ 𝐶)

Assertion

Ref	Expression
prssbd	⊢ (𝜑 → 𝐵 ∈ 𝐶)

Proof of Theorem prssbd

Step	Hyp	Ref	Expression
1		simpr 489	. . . 4 ⊢ ((𝜑 ∧ 𝐴 ∈ V) → 𝐴 ∈ V)
2		prssbd.1	. . . . 5 ⊢ (𝜑 → 𝐵 ∈ 𝑉)
3	2	adantr 485	. . . 4 ⊢ ((𝜑 ∧ 𝐴 ∈ V) → 𝐵 ∈ 𝑉)
4		prssbd.2	. . . . 5 ⊢ (𝜑 → {𝐴, 𝐵} ⊆ 𝐶)
5	4	adantr 485	. . . 4 ⊢ ((𝜑 ∧ 𝐴 ∈ V) → {𝐴, 𝐵} ⊆ 𝐶)
6		prssg 4786	. . . . 5 ⊢ ((𝐴 ∈ V ∧ 𝐵 ∈ 𝑉) → ((𝐴 ∈ 𝐶 ∧ 𝐵 ∈ 𝐶) ↔ {𝐴, 𝐵} ⊆ 𝐶))
7	6	biimpar 482	. . . 4 ⊢ (((𝐴 ∈ V ∧ 𝐵 ∈ 𝑉) ∧ {𝐴, 𝐵} ⊆ 𝐶) → (𝐴 ∈ 𝐶 ∧ 𝐵 ∈ 𝐶))
8	1, 3, 5, 7	syl21anc 850	. . 3 ⊢ ((𝜑 ∧ 𝐴 ∈ V) → (𝐴 ∈ 𝐶 ∧ 𝐵 ∈ 𝐶))
9	8	simprd 500	. 2 ⊢ ((𝜑 ∧ 𝐴 ∈ V) → 𝐵 ∈ 𝐶)
10		prprc1 4732	. . . . 5 ⊢ (¬ 𝐴 ∈ V → {𝐴, 𝐵} = {𝐵})
11	10	adantl 486	. . . 4 ⊢ ((𝜑 ∧ ¬ 𝐴 ∈ V) → {𝐴, 𝐵} = {𝐵})
12	4	adantr 485	. . . 4 ⊢ ((𝜑 ∧ ¬ 𝐴 ∈ V) → {𝐴, 𝐵} ⊆ 𝐶)
13	11, 12	eqsstrrd 3973	. . 3 ⊢ ((𝜑 ∧ ¬ 𝐴 ∈ V) → {𝐵} ⊆ 𝐶)
14		snssg 4750	. . . 4 ⊢ (𝐵 ∈ 𝑉 → (𝐵 ∈ 𝐶 ↔ {𝐵} ⊆ 𝐶))
15	14	biimpar 482	. . 3 ⊢ ((𝐵 ∈ 𝑉 ∧ {𝐵} ⊆ 𝐶) → 𝐵 ∈ 𝐶)
16	2, 13, 15	syl2an2r 697	. 2 ⊢ ((𝜑 ∧ ¬ 𝐴 ∈ V) → 𝐵 ∈ 𝐶)
17	9, 16	pm2.61dan 824	1 ⊢ (𝜑 → 𝐵 ∈ 𝐶)

Syntax hints:  ¬ wn 3   → wi 4   ∧ wa 400   = wceq 1570   ∈ wcel 2143  Vcvv 3455   ⊆ wss 3906  {csn 4590  {cpr 4592

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1825  ax-4 1839  ax-5 1940  ax-6 1997  ax-7 2038  ax-8 2145  ax-9 2153  ax-ext 2735

This theorem depends on definitions:  df-bi 210  df-an 401  df-or 861  df-tru 1573  df-fal 1583  df-ex 1810  df-sb 2097  df-clab 2742  df-cleq 2755  df-clel 2838  df-v 3457  df-dif 3909  df-un 3911  df-ss 3923  df-nul 4288  df-sn 4591  df-pr 4593

This theorem is referenced by:  constrllcllem  34123  constrlccllem  34124