
theorem
  for T be full Tree holds FinSeqLevel(1,T).2 = <* 1 *>
proof
  let T be full Tree;
A1: 0*1 = <* FALSE *> by FINSEQ_2:59;
   reconsider t =<* FALSE *> as Element of 1-tuples_on BOOLEAN
     by FINSEQ_2:131;
  thus FinSeqLevel(1,T).2 = FinSeqLevel(1,T).(2 to_power 1) by POWER:25
    .=  'not' t by A1,Th16
    .= <* 1 *> by BINARI_3:14;
end;
