reserve f for Function;
reserve n,k,n1 for Nat;
reserve r,p for Real;
reserve x,y,z for object;
reserve seq,seq1,seq2,seq3,seq9,seq19 for Real_Sequence;

theorem
  seq2/"(seq/"seq1)=(seq2(#)seq1)/"seq
proof
  thus seq2/"(seq/"seq1) = seq2(#)(seq1/"seq) by Th38
    .= seq2(#)(seq1(#)(seq"))
    .= (seq2(#)seq1)/"seq by Th14;
end;
