Name sets sometimes behave like multisets, and sometimes – after operations – like sets. Either use multiset interpretation always, or maybe we can make it dependent on the constraint where the expression occurs. In a !S constraint we are interested in multiset behaviour, in subset constraints probably not.

Submitted by Hendrik van Antwerpen on 7 September 2016 at 16:57

We settled on multiset semantics, because otherwise distinct tests do not make sense.