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| Mirrors > Home > MPE Home > Th. List > Mathboxes > aiota0def | Structured version Visualization version GIF version | ||
| Description: Example for a defined alternate iota being the empty set, i.e., ∀𝑦𝑥 ⊆ 𝑦 is a wff satisfied by a unique value 𝑥, namely 𝑥 = ∅ (the empty set is the one and only set which is a subset of every set). This corresponds to iota0def 47050. (Contributed by AV, 25-Aug-2022.) |
| Ref | Expression |
|---|---|
| aiota0def | ⊢ (℩'𝑥∀𝑦 𝑥 ⊆ 𝑦) = ∅ |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | 0ex 5307 | . 2 ⊢ ∅ ∈ V | |
| 2 | al0ssb 5308 | . . 3 ⊢ (∀𝑦 𝑥 ⊆ 𝑦 ↔ 𝑥 = ∅) | |
| 3 | 2 | ax-gen 1795 | . 2 ⊢ ∀𝑥(∀𝑦 𝑥 ⊆ 𝑦 ↔ 𝑥 = ∅) |
| 4 | eqeq2 2749 | . . . . . 6 ⊢ (𝑧 = ∅ → (𝑥 = 𝑧 ↔ 𝑥 = ∅)) | |
| 5 | 4 | bibi2d 342 | . . . . 5 ⊢ (𝑧 = ∅ → ((∀𝑦 𝑥 ⊆ 𝑦 ↔ 𝑥 = 𝑧) ↔ (∀𝑦 𝑥 ⊆ 𝑦 ↔ 𝑥 = ∅))) |
| 6 | 5 | albidv 1920 | . . . 4 ⊢ (𝑧 = ∅ → (∀𝑥(∀𝑦 𝑥 ⊆ 𝑦 ↔ 𝑥 = 𝑧) ↔ ∀𝑥(∀𝑦 𝑥 ⊆ 𝑦 ↔ 𝑥 = ∅))) |
| 7 | eqeq2 2749 | . . . 4 ⊢ (𝑧 = ∅ → ((℩'𝑥∀𝑦 𝑥 ⊆ 𝑦) = 𝑧 ↔ (℩'𝑥∀𝑦 𝑥 ⊆ 𝑦) = ∅)) | |
| 8 | 6, 7 | imbi12d 344 | . . 3 ⊢ (𝑧 = ∅ → ((∀𝑥(∀𝑦 𝑥 ⊆ 𝑦 ↔ 𝑥 = 𝑧) → (℩'𝑥∀𝑦 𝑥 ⊆ 𝑦) = 𝑧) ↔ (∀𝑥(∀𝑦 𝑥 ⊆ 𝑦 ↔ 𝑥 = ∅) → (℩'𝑥∀𝑦 𝑥 ⊆ 𝑦) = ∅))) |
| 9 | aiotaval 47107 | . . 3 ⊢ (∀𝑥(∀𝑦 𝑥 ⊆ 𝑦 ↔ 𝑥 = 𝑧) → (℩'𝑥∀𝑦 𝑥 ⊆ 𝑦) = 𝑧) | |
| 10 | 8, 9 | vtoclg 3554 | . 2 ⊢ (∅ ∈ V → (∀𝑥(∀𝑦 𝑥 ⊆ 𝑦 ↔ 𝑥 = ∅) → (℩'𝑥∀𝑦 𝑥 ⊆ 𝑦) = ∅)) |
| 11 | 1, 3, 10 | mp2 9 | 1 ⊢ (℩'𝑥∀𝑦 𝑥 ⊆ 𝑦) = ∅ |
| Colors of variables: wff setvar class |
| Syntax hints: → wi 4 ↔ wb 206 ∀wal 1538 = wceq 1540 ∈ wcel 2108 Vcvv 3480 ⊆ wss 3951 ∅c0 4333 ℩'caiota 47095 |
| This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1795 ax-4 1809 ax-5 1910 ax-6 1967 ax-7 2007 ax-8 2110 ax-9 2118 ax-10 2141 ax-11 2157 ax-12 2177 ax-ext 2708 ax-nul 5306 |
| This theorem depends on definitions: df-bi 207 df-an 396 df-or 849 df-tru 1543 df-fal 1553 df-ex 1780 df-nf 1784 df-sb 2065 df-mo 2540 df-eu 2569 df-clab 2715 df-cleq 2729 df-clel 2816 df-nfc 2892 df-ne 2941 df-ral 3062 df-rex 3071 df-rab 3437 df-v 3482 df-dif 3954 df-un 3956 df-in 3958 df-ss 3968 df-nul 4334 df-sn 4627 df-pr 4629 df-uni 4908 df-int 4947 df-iota 6514 df-aiota 47097 |
| This theorem is referenced by: (None) |
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