reserve x,y,y1,y2 for set;
reserve C for non empty set;
reserve c for Element of C;
reserve f,h,g,h1 for Membership_Func of C;

theorem
  for a,b,c be Real st 0 <= c holds c*max(a,b) = max(c*a,c*b) & c*min(a,
  b) = min(c*a,c*b) by Lm1,Lm2;
