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
  (-seq1)(#)seq2=-(seq1(#)seq2) & seq1(#)(-seq2)=-(seq1(#)seq2)
by Th12;
