reserve

  k,n,m,i,j for Element of NAT,
  K for Field;
reserve L for non empty addLoopStr;
reserve G for non empty multLoopStr;

theorem Th23:
  for n, i being Nat holds len Base_FinSeq(K,n,i)=n
proof
  let n, i be Nat;
  len (Replace((n |-> (0.K)),i,1.K)) = len (n |-> (0.K)) by FINSEQ_7:5
    .= n by CARD_1:def 7;
  hence thesis;
end;
