theorem
  exp(K,1) = K & exp(1,K) = 1
proof
  thus exp(K,1) = card K by FUNCT_5:58,ORDINAL3:15
    .= K;
  thus exp(1,K)
     = card {K --> {}} by FUNCT_5:59,ORDINAL3:15
    .= 1 by CARD_1:30;
end;
