摘要
We prove the existence of a dense subset %26#916; of [0,4] such that for all %26#945;%26#8712;%26#916; there exists a subgroup X%26#945; of infinite rank of %26#8484;[z] such that X%26#945; is a discrete subgroup of C[0,%26#946;] for all %26#946;%26#8805;%26#945; but it is not a discrete subgroup of C[0,%26#946;] for any %26#946;%26#8712;(0,%26#945;).