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
  seq is non-zero & seq1 is non-zero implies seq/"seq1 is non-zero
proof
  assume that
A1: seq is non-zero and
A2: seq1 is non-zero;
  seq1" is non-zero by A2,Th32;
  hence thesis by A1,Th33;
end;
