
theorem
{f where f is Function of REAL,REAL, a,b,c,d is Real:
 b <> 0 & for x be Real holds f.x= max(0,min(1, c*(1-|.(x-a)/b.|)))}
 c= Membership_Funcs (REAL)
 proof
  let g be object;
  assume g in {f where f is Function of REAL,REAL, a,b,c,d is Real:
  b <> 0 & for x be Real holds f.x= max(0,min(1, c*(1-|.(x-a)/b.|)))}; then
  consider f be Function of REAL,REAL, a,b,c,d be Real such that
  A1: f=g and
  b <> 0 and
  A2: for x be Real holds f.x= max(0,min(1, c*(1-|.(x-a)/b.|)));
  g is FuzzySet of REAL by A1,A2,MM60;
  hence thesis by Def1;
end;
