 reserve W for WA-Lattice;
 reserve a,b,c for Element of W;
 reserve W for pcs-Compatible pcs-tol-reflexive pcs-tol-symmetric WAP-Lattice;
 reserve a,b for Element of W;

theorem
  for x,y being Element of W st
    x (--) y holds y (--) x;   :: x T y -> y T x
