
theorem Th29:
for X be non empty set, S be SigmaField of X, E be Element of S,
 f be PartFunc of X,ExtREAL st E = {} holds f is E-measurable
proof
    let X be non empty set, S be SigmaField of X, E be Element of S,
    f be PartFunc of X,ExtREAL;
    assume E = {}; then
    for r be Real holds E /\ less_dom(f,r) in S;
    hence f is E-measurable by MESFUNC1:def 16;
end;
