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Description: Define the topology extractor function. This differs from df-tset when a structure has been restricted using df-ress ; in this case the TopSet component will still have a topology over the larger set, and this function fixes this by restricting the topology as well. (Contributed by Mario Carneiro, 13-Aug-2015)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | df-topn | ⊢ TopOpen = ( 𝑤 ∈ V ↦ ( ( TopSet ‘ 𝑤 ) ↾t ( Base ‘ 𝑤 ) ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 0 | ctopn | ⊢ TopOpen | |
| 1 | vw | ⊢ 𝑤 | |
| 2 | cvv | ⊢ V | |
| 3 | cts | ⊢ TopSet | |
| 4 | 1 | cv | ⊢ 𝑤 |
| 5 | 4 3 | cfv | ⊢ ( TopSet ‘ 𝑤 ) |
| 6 | crest | ⊢ ↾t | |
| 7 | cbs | ⊢ Base | |
| 8 | 4 7 | cfv | ⊢ ( Base ‘ 𝑤 ) |
| 9 | 5 8 6 | co | ⊢ ( ( TopSet ‘ 𝑤 ) ↾t ( Base ‘ 𝑤 ) ) |
| 10 | 1 2 9 | cmpt | ⊢ ( 𝑤 ∈ V ↦ ( ( TopSet ‘ 𝑤 ) ↾t ( Base ‘ 𝑤 ) ) ) |
| 11 | 0 10 | wceq | ⊢ TopOpen = ( 𝑤 ∈ V ↦ ( ( TopSet ‘ 𝑤 ) ↾t ( Base ‘ 𝑤 ) ) ) |