Definition df-topgen 12726

Description: Define a function that converts a basis to its corresponding topology. Equivalent to the definition of a topology generated by a basis in [Munkres] p. 78. (Contributed by NM, 16-Jul-2006.)

Assertion

Ref	Expression
df-topgen	|- topGen = ( x e. _V |-> { y | y C_ U. ( x i^i ~P y ) } )

Distinct variable group:   x, y

Detailed syntax breakdown of Definition df-topgen

Step	Hyp	Ref	Expression
1		ctg 12720	. 2 class topGen
2		vx	. . 3 setvar x
3		cvv 2749	. . 3 class _V
4		vy	. . . . . 6 setvar y
5	4	cv 1362	. . . . 5 class y
6	2	cv 1362	. . . . . . 7 class x
7	5	cpw 3587	. . . . . . 7 class ~P y
8	6, 7	cin 3140	. . . . . 6 class ( x i^i ~P y )
9	8	cuni 3821	. . . . 5 class U. ( x i^i ~P y )
10	5, 9	wss 3141	. . . 4 wff y C_ U. ( x i^i ~P y )
11	10, 4	cab 2173	. . 3 class { y | y C_ U. ( x i^i ~P y ) }
12	2, 3, 11	cmpt 4076	. 2 class ( x e. _V |-> { y | y C_ U. ( x i^i ~P y ) } )
13	1, 12	wceq 1363	1 wff topGen = ( x e. _V |-> { y | y C_ U. ( x i^i ~P y ) } )

This definition is referenced by:  tgval  12728  eltg4i  13795  eltg3  13797  tg1  13799  tg2  13800  tgclb  13805