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
  for IT being non-zero Complex_Sequence holds rng IT c= COMPLEX \ {0c}
    by ORDINAL1:def 15,ZFMISC_1:34;
