
theorem
for a,b be Real, f be Function of REAL,REAL st
(for th be Real holds f.th= 1/2*cos(a*th+b)+1/2)
holds f is FuzzySet of REAL
proof
 let a,b be Real;
 let f be Function of REAL,REAL;
 assume for th be Real holds f.th= 1/2*cos(a*th+b)+1/2;
 then
 f in {f where f is Function of REAL,REAL :
 ex a,b be Real st for th be Real holds f.th= 1/2*cos(a*th+b)+1/2};
 hence thesis by Def1,TrF2;
end;
