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Mirrors > Home > MPE Home > Th. List > mosneq | Structured version Visualization version GIF version |
Description: There exists at most one set whose singleton is equal to a given class. See also moeq 3700. (Contributed by BJ, 24-Sep-2022.) |
Ref | Expression |
---|---|
mosneq | ⊢ ∃*𝑥{𝑥} = 𝐴 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | eqtr3 2845 | . . . 4 ⊢ (({𝑥} = 𝐴 ∧ {𝑦} = 𝐴) → {𝑥} = {𝑦}) | |
2 | vex 3499 | . . . . 5 ⊢ 𝑥 ∈ V | |
3 | 2 | sneqr 4773 | . . . 4 ⊢ ({𝑥} = {𝑦} → 𝑥 = 𝑦) |
4 | 1, 3 | syl 17 | . . 3 ⊢ (({𝑥} = 𝐴 ∧ {𝑦} = 𝐴) → 𝑥 = 𝑦) |
5 | 4 | gen2 1797 | . 2 ⊢ ∀𝑥∀𝑦(({𝑥} = 𝐴 ∧ {𝑦} = 𝐴) → 𝑥 = 𝑦) |
6 | sneq 4579 | . . . 4 ⊢ (𝑥 = 𝑦 → {𝑥} = {𝑦}) | |
7 | 6 | eqeq1d 2825 | . . 3 ⊢ (𝑥 = 𝑦 → ({𝑥} = 𝐴 ↔ {𝑦} = 𝐴)) |
8 | 7 | mo4 2650 | . 2 ⊢ (∃*𝑥{𝑥} = 𝐴 ↔ ∀𝑥∀𝑦(({𝑥} = 𝐴 ∧ {𝑦} = 𝐴) → 𝑥 = 𝑦)) |
9 | 5, 8 | mpbir 233 | 1 ⊢ ∃*𝑥{𝑥} = 𝐴 |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ∧ wa 398 ∀wal 1535 = wceq 1537 ∃*wmo 2620 {csn 4569 |
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-10 2145 ax-11 2161 ax-12 2177 ax-ext 2795 |
This theorem depends on definitions: df-bi 209 df-an 399 df-or 844 df-tru 1540 df-ex 1781 df-nf 1785 df-sb 2070 df-mo 2622 df-clab 2802 df-cleq 2816 df-clel 2895 df-nfc 2965 df-v 3498 df-sn 4570 |
This theorem is referenced by: euabsneu 43270 |
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