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| Mirrors > Home > ILE Home > Th. List > if0elpw | GIF version | ||
| Description: A conditional class with the False alternative being sent to the empty class is an element of the powerset of the class corresponding to the True alternative when that class is a set. This statement requires fewer axioms than the general case ifelpwung 4622. (Contributed by BJ, 5-May-2026.) |
| Ref | Expression |
|---|---|
| if0elpw | ⊢ (𝐴 ∈ 𝑉 → if(𝜑, 𝐴, ∅) ∈ 𝒫 𝐴) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | if0ss 3639 | . 2 ⊢ if(𝜑, 𝐴, ∅) ⊆ 𝐴 | |
| 2 | elpw2g 4287 | . 2 ⊢ (𝐴 ∈ 𝑉 → (if(𝜑, 𝐴, ∅) ∈ 𝒫 𝐴 ↔ if(𝜑, 𝐴, ∅) ⊆ 𝐴)) | |
| 3 | 1, 2 | mpbiri 168 | 1 ⊢ (𝐴 ∈ 𝑉 → if(𝜑, 𝐴, ∅) ∈ 𝒫 𝐴) |
| Colors of variables: wff set class |
| Syntax hints: → wi 4 ∈ wcel 2209 ⊆ wss 3220 ∅c0 3520 ifcif 3635 𝒫 cpw 3685 |
| 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-in1 623 ax-in2 624 ax-io 721 ax-5 1500 ax-7 1501 ax-gen 1502 ax-ie1 1546 ax-ie2 1547 ax-8 1557 ax-10 1558 ax-11 1559 ax-i12 1560 ax-bndl 1562 ax-4 1563 ax-17 1579 ax-i9 1583 ax-ial 1587 ax-i5r 1588 ax-ext 2220 ax-sep 4244 |
| This theorem depends on definitions: df-bi 117 df-tru 1405 df-fal 1408 df-nf 1514 df-sb 1816 df-clab 2225 df-cleq 2231 df-clel 2234 df-nfc 2381 df-rab 2537 df-v 2823 df-dif 3222 df-un 3224 df-in 3226 df-ss 3233 df-nul 3521 df-if 3636 df-pw 3687 |
| This theorem is referenced by: fmelpw1o 7596 |
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