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| Mirrors > Home > MPE Home > Th. List > Mathboxes > bj-prexg | Structured version Visualization version GIF version | ||
| Description: Existence of unordered pairs formed on sets, proved from ax-bj-sn 37523 and ax-bj-bun 37527. Contrary to bj-prex 37530, this proof is intuitionistically valid and does not require ax-nul 5258. (Contributed by BJ, 12-Jan-2025.) (Proof modification is discouraged.) |
| Ref | Expression |
|---|---|
| bj-prexg | ⊢ ((𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑊) → {𝐴, 𝐵} ∈ V) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | df-pr 4587 | . 2 ⊢ {𝐴, 𝐵} = ({𝐴} ∪ {𝐵}) | |
| 2 | bj-snexg 37524 | . . 3 ⊢ (𝐴 ∈ 𝑉 → {𝐴} ∈ V) | |
| 3 | bj-snexg 37524 | . . 3 ⊢ (𝐵 ∈ 𝑊 → {𝐵} ∈ V) | |
| 4 | bj-unexg 37528 | . . 3 ⊢ (({𝐴} ∈ V ∧ {𝐵} ∈ V) → ({𝐴} ∪ {𝐵}) ∈ V) | |
| 5 | 2, 3, 4 | syl2an 605 | . 2 ⊢ ((𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑊) → ({𝐴} ∪ {𝐵}) ∈ V) |
| 6 | 1, 5 | eqeltrid 2868 | 1 ⊢ ((𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑊) → {𝐴, 𝐵} ∈ V) |
| Colors of variables: wff setvar class |
| Syntax hints: → wi 4 ∧ wa 399 ∈ wcel 2144 Vcvv 3456 ∪ cun 3904 {csn 4584 {cpr 4586 |
| This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1817 ax-4 1831 ax-5 1932 ax-6 1989 ax-7 2030 ax-8 2146 ax-9 2154 ax-12 2214 ax-ext 2736 ax-bj-sn 37523 ax-bj-bun 37527 |
| This theorem depends on definitions: df-bi 209 df-an 400 df-or 859 df-tru 1565 df-ex 1802 df-sb 2093 df-clab 2743 df-cleq 2756 df-clel 2839 df-v 3458 df-un 3911 df-sn 4585 df-pr 4587 |
| This theorem is referenced by: (None) |
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