Definition df-topn 17468

Description: Define the topology extractor function. This differs from df-tset 17316 when a structure has been restricted using df-ress 17275; 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.)

Assertion

Ref	Expression
df-topn	⊢ TopOpen = (𝑤 ∈ V ↦ ((TopSet‘𝑤) ↾t (Base‘𝑤)))

Detailed syntax breakdown of Definition df-topn

Step	Hyp	Ref	Expression
1		ctopn 17466	. 2 class TopOpen
2		vw	. . 3 setvar 𝑤
3		cvv 3480	. . 3 class V
4	2	cv 1539	. . . . 5 class 𝑤
5		cts 17303	. . . . 5 class TopSet
6	4, 5	cfv 6561	. . . 4 class (TopSet‘𝑤)
7		cbs 17247	. . . . 5 class Base
8	4, 7	cfv 6561	. . . 4 class (Base‘𝑤)
9		crest 17465	. . . 4 class ↾t
10	6, 8, 9	co 7431	. . 3 class ((TopSet‘𝑤) ↾t (Base‘𝑤))
11	2, 3, 10	cmpt 5225	. 2 class (𝑤 ∈ V ↦ ((TopSet‘𝑤) ↾t (Base‘𝑤)))
12	1, 11	wceq 1540	1 wff TopOpen = (𝑤 ∈ V ↦ ((TopSet‘𝑤) ↾t (Base‘𝑤)))

This definition is referenced by:  topnfn  17470  topnval  17479