Hi, that’s indeed a bit of a design problem in the current MiniZinc library. We’ve got a solution for it (at the MiniZinc level, so solvers wouldn’t have to change) but it’s not fully implemented yet (it would involve having standard decompositions for all reified globals, and solvers being able to override them if they have dedicated reified constraints).
Cheers, Guido -- GUIDO TACK Senior Lecturer Information Technology Monash University Level 6, Room 6.40, Building H, Caulfield Campus 900 Dandenong Road Caulfield East VIC 3145 Australia T: +61 3 9903 1214 E: guido.t...@monash.edu <mailto:guido.t...@monash.edu> http://www.csse.monash.edu/~guidot/ <http://www.csse.monash.edu/~guidot/> > On 2 May 2016, at 7:04 PM, Alexander Schiendorfer > <alexander.schiendor...@informatik.uni-augsburg.de> wrote: > > Hi everyone, > > I have a question regarding the MiniZinc globals definition of lex_less > (among others) in Gecode, > in particular how their reified version is treated. > > Say I wanted to solve the following model: > > % test if lexless can be used in reified mode > array[1..5] of var 0..10: x; > array[1..5] of var 0..10: y; > > include "globals.mzn"; > constraint alldifferent(x); > > constraint lex_less(x, y) \/ x[1] = 9; > solve satisfy; > > > Since, for example, the Gecode-specific "lex_less.mzn" file overwrites all > predicate definitions there, we also > lose the "lex_less_int_reif" decomposition specified in the standard > MZN-library. > > Wouldn't it be nicer to have this decomposition available until there is a > reified variant of "lex_less"? > I tried copying "predicate lex_less_int_reif(...)" from "std" to Gecode's > "lex_less.mzn" and it made the above > model solvable. > > Is there a particular reason for not doing this? > > Cheers, > Alex > > -- > Alexander Schiendorfer, M.Sc. > Institute for Software & Systems Engineering > Raum 3043, Gebäude N > Universität Augsburg > > Web: > http://www.informatik.uni-augsburg.de/lehrstuehle/swt/se/staff/aschiendorfer/ > Tel.: +49 (821) 598 - 2196 > E-Mail: alexander.schiendor...@informatik.uni-augsburg.de > > SASO’16 - Tenth IEEE International Conference on Self-Adaptive and Self > Organizing Systems > Augsburg, Germany, 12-16 September 2016 > @SASO2016Conf > http://uni-augsburg.de/saso2016 – Submit! Announce! Participate! > > > _______________________________________________ > Gecode users mailing list > users@gecode.org > https://www.gecode.org/mailman/listinfo/gecode-users
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