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} )