Metamath Proof Explorer


Definition df-ae

Description: Define 'almost everywhere' with regard to a measure M . A property holds almost everywhere if the measure of the set where it does not hold has measure zero. (Contributed by Thierry Arnoux, 20-Oct-2017)

Ref Expression
Assertion df-ae
|- ae = { <. a , m >. | ( m ` ( U. dom m \ a ) ) = 0 }

Detailed syntax breakdown

Step Hyp Ref Expression
0 cae
 |-  ae
1 va
 |-  a
2 vm
 |-  m
3 2 cv
 |-  m
4 3 cdm
 |-  dom m
5 4 cuni
 |-  U. dom m
6 1 cv
 |-  a
7 5 6 cdif
 |-  ( U. dom m \ a )
8 7 3 cfv
 |-  ( m ` ( U. dom m \ a ) )
9 cc0
 |-  0
10 8 9 wceq
 |-  ( m ` ( U. dom m \ a ) ) = 0
11 10 1 2 copab
 |-  { <. a , m >. | ( m ` ( U. dom m \ a ) ) = 0 }
12 0 11 wceq
 |-  ae = { <. a , m >. | ( m ` ( U. dom m \ a ) ) = 0 }