reserve f for Function;
reserve n,k,n1 for Element of NAT;
reserve r,p for Complex;
reserve x,y for set;
reserve seq,seq1,seq2,seq3,seq9,seq19 for Complex_Sequence;

theorem
  |.seq9/"seq.|=|.seq9.|/"|.seq.|
proof
  thus |.seq9/"seq.|=|.seq9.|(#)|.seq".| by Th45
    .=|.seq9.|/"|.seq.| by Th46;
end;
