Description: If the relation produces closed sets, preimage maps are measurable sets. (Contributed by Thierry Arnoux, 21-Jan-2017)
Ref | Expression | ||
---|---|---|---|
Hypotheses | orrvccel.1 | |
|
orrvccel.2 | |
||
orrvccel.4 | |
||
orrvccel.5 | |
||
Assertion | orrvccel | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | orrvccel.1 | |
|
2 | orrvccel.2 | |
|
3 | orrvccel.4 | |
|
4 | orrvccel.5 | |
|
5 | domprobsiga | |
|
6 | 1 5 | syl | |
7 | retop | |
|
8 | 7 | a1i | |
9 | 1 | rrvmbfm | |
10 | 2 9 | mpbid | |
11 | df-brsiga | |
|
12 | 11 | oveq2i | |
13 | 10 12 | eleqtrdi | |
14 | uniretop | |
|
15 | rabeq | |
|
16 | 14 15 | ax-mp | |
17 | 16 4 | eqeltrrid | |
18 | 6 8 13 3 17 | orvccel | |