Select

Note: from now on, this module is only available as an ozmake package.

This module implements the selection constraints for finite domains and for finite sets.

the selection constraint S={Select.fs [S1 ... Sn] I} has the same declarative semantics as S={Nth [S1 ... Sn] I}, i.e. it unifies X with the Ith element of sequence [S1 ... Sn]. However, it is much more powerful because it is also a constraint. All of S, S1, ..., Sn, and I can be constrained variables. In particular:

• I can be a finite domain variable. If S is incompatible with Sk then integer k is removed from the domain of I.

• the selection constraint provides a form of constructive disjunction. With M={Select.fd [M1 ... Mn] I} the domain of M is the union of those of the Mi for i in the domain of I. Similarly, with S={Select.fs [S1 ... Sn] I} the lower (resp. upper) bound of S is the intersection (resp. union) of the lower (resp. upper) bounds of Si for i in the domain of I.

As of version 1.3, the module also implements the selection union constraint {Select.union [S1 ... Sn] SI} which returns the union of the sets Si for i in SI.

As of version 1.5, the module also implements the selection intersection constraint {Select.inter [S1 ... Sn] SI} which returns the intersection of the sets Si for i in SI.

As of version 1.6, this package provides the sequenced union constraint {Select.seqUnion [S1 ... Sn] S} whereS is the union of the sets Si which are additionally constrained to be sequential, i.e. for i<j all elements of Si are smaller than elements of Sj.

Version 1.8 - added indexedUnion constraint {Select.indexedUnion [I1#S1 ... In#Sn] SI} which returns the union of the Sk for Ik in SI.