theorem Th12:
  A <> B implies card Election(A,n,B,k) = (n+k) choose n
proof
  assume
A1: A<>B;
  thus card Election(A,n,B,k) = card Choose(Seg (n+k),n,A,B) by Th10
         .= card Seg (n+k) choose n by A1,CARD_FIN:16
         .= (n+k) choose n by FINSEQ_1:57;
end;
