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
  seq2/"(seq/"seq1)=(seq2(#)seq1)/"seq
proof
  now
    let n;
    thus (seq2/"(seq/"seq1)).n=((seq2(#)(seq1/"seq))).n by Th33
      .=((seq2(#)seq1)(#)(seq")).n by Th8
      .=((seq2(#)seq1)/"seq).n;
  end;
  hence thesis by FUNCT_2:63;
end;
