theorem
  for X1, X2 being non empty SubSpace of X st X1 meets X2 for f1 being
  continuous Function of X1,Y, f2 being continuous Function of X2,Y st f1|(X1
meet X2) = f2|(X1 meet X2) holds X1,X2 are_weakly_separated implies f1 union f2
  is continuous Function of X1 union X2,Y
proof
  let X1, X2 be non empty SubSpace of X such that
A1: X1 meets X2;
  let f1 be continuous Function of X1,Y, f2 be continuous Function of X2,Y;
  assume f1|(X1 meet X2) = f2|(X1 meet X2);
  then
A2: (f1 union f2)|X1 = f1 & (f1 union f2)|X2 = f2 by A1,Th128;
  assume X1,X2 are_weakly_separated;
  hence thesis by A2,Th114;
end;
