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Mathbox for Glauco Siliprandi |
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Mirrors > Home > MPE Home > Th. List > Mathboxes > nsstr | Structured version Visualization version GIF version |
Description: If it's not a subclass, it's not a subclass of a smaller one. (Contributed by Glauco Siliprandi, 26-Jun-2021.) |
Ref | Expression |
---|---|
nsstr | ⊢ ((¬ 𝐴 ⊆ 𝐵 ∧ 𝐶 ⊆ 𝐵) → ¬ 𝐴 ⊆ 𝐶) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | sstr 3923 | . . . 4 ⊢ ((𝐴 ⊆ 𝐶 ∧ 𝐶 ⊆ 𝐵) → 𝐴 ⊆ 𝐵) | |
2 | 1 | ancoms 462 | . . 3 ⊢ ((𝐶 ⊆ 𝐵 ∧ 𝐴 ⊆ 𝐶) → 𝐴 ⊆ 𝐵) |
3 | 2 | adantll 713 | . 2 ⊢ (((¬ 𝐴 ⊆ 𝐵 ∧ 𝐶 ⊆ 𝐵) ∧ 𝐴 ⊆ 𝐶) → 𝐴 ⊆ 𝐵) |
4 | simpll 766 | . 2 ⊢ (((¬ 𝐴 ⊆ 𝐵 ∧ 𝐶 ⊆ 𝐵) ∧ 𝐴 ⊆ 𝐶) → ¬ 𝐴 ⊆ 𝐵) | |
5 | 3, 4 | pm2.65da 816 | 1 ⊢ ((¬ 𝐴 ⊆ 𝐵 ∧ 𝐶 ⊆ 𝐵) → ¬ 𝐴 ⊆ 𝐶) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 → wi 4 ∧ wa 399 ⊆ wss 3881 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1797 ax-4 1811 ax-5 1911 ax-6 1970 ax-7 2015 ax-8 2113 ax-9 2121 ax-ext 2770 |
This theorem depends on definitions: df-bi 210 df-an 400 df-ex 1782 df-sb 2070 df-clab 2777 df-cleq 2791 df-clel 2870 df-v 3443 df-in 3888 df-ss 3898 |
This theorem is referenced by: mbfpsssmf 43416 |
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