theorem
  Seg 8 = {1,2,3,4,5,6,7,8}
proof
  thus Seg 8 = {1,2,3,4,5,6,7} \/ {7 + 1} by Th5,FINSEQ_1:9
    .= {1,2,3,4,5,6,7,8} by ENUMSET1:28;
end;
