reserve i, j, n for Nat,
  f for non constant standard special_circular_sequence,
  g for clockwise_oriented non constant standard special_circular_sequence,
  p, q for Point of TOP-REAL 2,
  P for Subset of TOP-REAL 2,
  C for compact non vertical non horizontal Subset of TOP-REAL 2,
  G for Go-board;

theorem
  for f being FinSequence of TOP-REAL n st L~f <> {} holds 2 <= len f
proof
  let f be FinSequence of TOP-REAL n;
  assume L~f <> {};
  then len f <> 0 & len f <> 1 by TOPREAL1:22;
  then len f > 1 by NAT_1:25;
  then len f >= 1 + 1 by NAT_1:13;
  hence thesis;
end;
