theorem :: TOPREAL1:27

ex P1, P2 being non empty Subset of (TOP-REAL 2) st
( P1 is being_S-P_arc & P2 is being_S-P_arc & R^2-unit_square = P1 \/ P2 & P1 /\ P2 = {|[0,0]|,|[1,1]|} )