theorem MyNeed:
for
Omega being non
empty set for
Sigma being
SigmaField of
Omega for
I being non
empty real-membered set st
I = {1,2,3} &
Sigma = bool {1,2,3,4} &
Omega = {1,2,3,4} holds
ex
MyFunc being
Filtration of
I,
Sigma st
(
MyFunc . 1
= Special_SigmaField1 &
MyFunc . 2
= Special_SigmaField2 &
MyFunc . 3
= Trivial-SigmaField {1,2,3,4} )