let X, Y be non empty TopSpace; :: thesis: for f being Function of X,Y
for X1, X2 being non empty SubSpace of X st X = X1 union X2 & X1,X2 are_weakly_separated holds
( f is continuous Function of X,Y iff ( f | X1 is continuous Function of X1,Y & f | X2 is continuous Function of X2,Y ) )

let f be Function of X,Y; :: thesis: for X1, X2 being non empty SubSpace of X st X = X1 union X2 & X1,X2 are_weakly_separated holds
( f is continuous Function of X,Y iff ( f | X1 is continuous Function of X1,Y & f | X2 is continuous Function of X2,Y ) )

let X1, X2 be non empty SubSpace of X; :: thesis: ( X = X1 union X2 & X1,X2 are_weakly_separated implies ( f is continuous Function of X,Y iff ( f | X1 is continuous Function of X1,Y & f | X2 is continuous Function of X2,Y ) ) )
assume that
A1: X = X1 union X2 and
A2: X1,X2 are_weakly_separated ; :: thesis: ( f is continuous Function of X,Y iff ( f | X1 is continuous Function of X1,Y & f | X2 is continuous Function of X2,Y ) )
thus ( f is continuous Function of X,Y implies ( f | X1 is continuous Function of X1,Y & f | X2 is continuous Function of X2,Y ) ) ; :: thesis: ( f | X1 is continuous Function of X1,Y & f | X2 is continuous Function of X2,Y implies f is continuous Function of X,Y )
assume ( f | X1 is continuous Function of X1,Y & f | X2 is continuous Function of X2,Y ) ; :: thesis: f is continuous Function of X,Y
then f | (X1 union X2) is continuous Function of (X1 union X2),Y by ;
hence f is continuous Function of X,Y by ; :: thesis: verum