theorem Th35:
  N-most R^2-unit_square = LSeg(|[0,1]|,|[1,1]|)
proof
  set X = R^2-unit_square;
  LSeg(|[ 0,0 ]|, |[ 0,1 ]|) \/ LSeg(|[ 0,1 ]|, |[ 1,1 ]|) c= X & LSeg(|[0
  ,1]| ,|[1,1]|) c= LSeg(|[ 0,0 ]|, |[ 0,1 ]|) \/ LSeg(|[ 0,1 ]|, |[ 1,1 ]|)
by XBOOLE_1:7;
  hence thesis by Th31,Th32,Th33,XBOOLE_1:1,28;
end;
