reserve x,x1,x2,y,y9,y1,y2,z,z1,z2 for object,P,X,X1,X2,Y,Y1,Y2,V,Z for set;

theorem Th45:
  for f being PartFunc of X,Y holds f in PFuncs(X,Y)
proof
  let f be PartFunc of X,Y;
  dom f c= X & rng f c= Y by RELAT_1:def 19;
  hence thesis by Def3;
end;
