Definition df-brsiga 30245

Description: A Borel Algebra is defined as a sigma-algebra generated by a topology. 'The' Borel sigma-algebra here refers to the sigma-algebra generated by the topology of open intervals on real numbers. The Borel algebra of a given topology J is the sigma-algebra generated by J, (sigaGen ` J ), so there is no need to introduce a special constant function for Borel sigma-algebra. (Contributed by Thierry Arnoux, 27-Dec-2016.)

Assertion

Ref	Expression
df-brsiga	|- 𝔅ℝ = (sigaGen ` ( topGen ` ran (,) ) )

Detailed syntax breakdown of Definition df-brsiga

Step	Hyp	Ref	Expression
1		cbrsiga 30244	. 2 class 𝔅ℝ
2		cioo 12175	. . . . 5 class (,)
3	2	crn 5115	. . . 4 class ran (,)
4		ctg 16098	. . . 4 class topGen
5	3, 4	cfv 5888	. . 3 class ( topGen ` ran (,) )
6		csigagen 30201	. . 3 class sigaGen
7	5, 6	cfv 5888	. 2 class (sigaGen ` ( topGen ` ran (,) ) )
8	1, 7	wceq 1483	1 wff 𝔅ℝ = (sigaGen ` ( topGen ` ran (,) ) )

This definition is referenced by:  brsiga  30246  brsigarn  30247  unibrsiga  30249  elmbfmvol2  30329  dya2iocbrsiga  30337  dya2icobrsiga  30338  sxbrsiga  30352  rrvadd  30514  rrvmulc  30515  orrvcval4  30526  orrvcoel  30527  orrvccel  30528