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| Mirrors > Home > ILE Home > Th. List > ssneldd | GIF version | ||
| Description: If an element is not in a class, it is also not in a subclass of that class. Deduction form. (Contributed by David Moews, 1-May-2017.) |
| Ref | Expression |
|---|---|
| ssneld.1 | ⊢ (𝜑 → 𝐴 ⊆ 𝐵) |
| ssneldd.2 | ⊢ (𝜑 → ¬ 𝐶 ∈ 𝐵) |
| Ref | Expression |
|---|---|
| ssneldd | ⊢ (𝜑 → ¬ 𝐶 ∈ 𝐴) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | ssneldd.2 | . 2 ⊢ (𝜑 → ¬ 𝐶 ∈ 𝐵) | |
| 2 | ssneld.1 | . . 3 ⊢ (𝜑 → 𝐴 ⊆ 𝐵) | |
| 3 | 2 | ssneld 3250 | . 2 ⊢ (𝜑 → (¬ 𝐶 ∈ 𝐵 → ¬ 𝐶 ∈ 𝐴)) |
| 4 | 1, 3 | mpd 13 | 1 ⊢ (𝜑 → ¬ 𝐶 ∈ 𝐴) |
| Colors of variables: wff set class |
| Syntax hints: ¬ wn 3 → wi 4 ∈ wcel 2209 ⊆ wss 3220 |
| 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-5 1500 ax-7 1501 ax-gen 1502 ax-ie1 1546 ax-ie2 1547 ax-8 1557 ax-11 1559 ax-4 1563 ax-17 1579 ax-i9 1583 ax-ial 1587 ax-i5r 1588 ax-ext 2220 |
| This theorem depends on definitions: df-bi 117 df-nf 1514 df-sb 1816 df-clab 2225 df-cleq 2231 df-clel 2234 df-in 3226 df-ss 3233 |
| This theorem is referenced by: 0nelrel 4819 addnqprlemfl 7920 addnqprlemfu 7921 mulnqprlemfl 7936 mulnqprlemfu 7937 cauappcvgprlemladdru 8017 hashfibclem 11265 fprodntrivap 12334 fprodssdc 12340 |
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