reserve x, y, X for set;
reserve E for non empty set;
reserve e for Element of E;
reserve u, u1, v, v1, v2, w, w9, w1, w2 for Element of E^omega;
reserve F for Subset of E^omega;
reserve i, k, l for Nat;
reserve TS for non empty transition-system over F;
reserve S, T for Subset of TS;

theorem Th8:
  not <%>E in Lex(E)
proof
  assume <%>E in Lex(E);
  then ex e st e in E & <%>E = <%e%> by FLANG_1:def 4;
  hence contradiction;
end;
