reserve i,j,k for Nat,
  r,s,r1,r2,s1,s2,sb,tb for Real,
  x for set,
  GX for non empty TopSpace;
reserve GZ for non empty TopSpace;
reserve f for non constant standard special_circular_sequence,
  G for non empty-yielding Matrix of TOP-REAL 2;

theorem Th6:
  (L~f)` <> {}
proof
  LSeg(1/2*((GoB f)*(1,width GoB f -' 1)+(GoB f)*(1,width GoB f))-|[1,0 ]|
  , (GoB f)*(1,width GoB f)+|[-1,1]|) misses (L~f) by GOBOARD8:33;
  then
  LSeg(1/2*((GoB f)*(1,width GoB f -' 1)+(GoB f)*(1,width GoB f))-|[1,0 ]|
  , (GoB f)*(1,width GoB f)+|[-1,1]|) c= (L~f)` by SUBSET_1:23;
  hence thesis;
end;
