reserve i,j,k,l,m,n for Nat,
  D for non empty set,
  f for FinSequence of D;
reserve X for compact Subset of TOP-REAL 2;
reserve r for Real;

theorem Th38:
  for f being non constant standard special_circular_sequence, i,j
  st i < j & (1 < i & j <= len f or 1 <= i & j < len f) holds mid(f,i,j) is
  S-Sequence_in_R2
proof
  let f be non constant standard special_circular_sequence,i,j;
  assume i < j &( 1 < i & j <= len f or 1 <= i & j < len f);
  then mid(f,j,i) is S-Sequence_in_R2 by Th37;
  then
  Rev Rev mid(f,i,j) = mid(f,i,j) & Rev mid(f,i,j) is S-Sequence_in_R2 by
FINSEQ_6:196;
  hence thesis;
end;
