“…Half-factoriality has been a central topic ever since the beginning of factorization theory (see the surveys [5,8,22], and [6,7,9,17] for some recent results). A classical result due to Carlitz states that a ring of integers, i.e., a principal order, is half-factorial if and only if its class group has at most two elements (see [2]; there are analogous results for Krull monoids, but for simplicity we restrict our discussion here to rings of integers).…”