theorem Th8:
  for C being non empty compact Subset of TOP-REAL 2
  holds C is vertical iff E-bound C <= W-bound C
proof
  let C be non empty compact Subset of TOP-REAL 2;
A1: E-bound C >= W-bound C by SPRECT_1:21;
  C is vertical iff W-bound C = E-bound C by SPRECT_1:15;
  hence thesis by A1,XXREAL_0:1;
end;
