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Written by Radoslaw Szymanek
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Monday, 30 May 2011 12:04 |
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Dear all, Scala programming language gets more and more acceptance in the community. It compiles to Java byte code and is executed using JVM. This makes it possible to use JaCoP directly in Scala by importing its packages. However, since Scala offers a nice way to define domain specific languages (DSL), we have developed an experimental implementation of the DSL for JaCoP solver. Our implementation uses several Scala features to define a clear way of using JaCoP solver. We overloaded operators to specify easily arithmetical, logical and set constraints. We also use the package object to gather global constraints and search methods. This together with Scala features, such as implicit conversions, simplifies use of JaCoP and makes it easier to understand.
The implementation (available on Sourceforge) is still experimental and we will be happy to get comments and proposals for improvements. We hope that this work will make it easier for Scala community to use JaCoP solver/CP technology.
Best regards,
Core Developer Team |
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Last Updated on Monday, 30 May 2011 12:09 |
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JaCoP version 3.1 is released |
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Written by Radoslaw Szymanek
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Monday, 07 February 2011 09:30 |
Dear users, We have just released JaCoP 3.1. This is a release that fixes few bugs as well as provides a new Binpacking constraint. The Binpacking constraint allows modeling of problems exhibiting bin packing problem structure. The addition of this constraint introduced changes to minizinc/fz library in JaCoP since the definitions of bin_packing.mzn, bin_packin_capa.mzn and bin_packing_load.mzn have been added. The JaCoP guide has been updated to explain how to use Binpacking constraint.
best regards,
Core Developer Team
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Last Updated on Monday, 07 February 2011 09:51 |
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JaCoP version 3.0 (RC1) is released |
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Written by Radoslaw Szymanek
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Wednesday, 01 September 2010 20:44 |
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Dear users, We make available JaCoP 3.0 RC1, which has been used in Minizinc
Challenge 2010. We are still working on the newest functionality (1)
as well as cleaning API to reduce the need of further changes in the
future. We look for your feedback so we can make the final release
3.0 as soon as possible. Here is the list of most important changes
since version 2.4.
1) The introduction of Network Flow constraint, which allows efficient
modeling of problems with network flow structure. The constraint
allows to specify minimum cost flow problem in terms of finite
domain variables. It uses network simplex algorithm as an
propagator for network-like structure. It is a very expressive
constraint where arc flow and arc unit costs can be specified by
variables.
2) The introduction of set package forced changes in the design of
core interfaces. There are IntVar and SetVar classes which inherit
from Var class. This change allowed to refactor and improve set package
so it is designed in cleaner and more efficient manner.
3) The introduction of special domain representation SmallDenseDomain,
which uses bits within a long primitive type to encode small
domains of range not larger than 64.
4) The introduction of Soft-alldifferent as well as Soft-GCC global
constraints. The soft-alldifferent constraint implements Variable
and Decomposition based violation metrics. The soft-gcc constraint
implements value based violation metric. Both are decomposed constraints
based on network flow constraint.
5) Examples have been updated by moving multiple solving functionality
from main function to test function, so user can easily see what is
the best model just by looking at main function. BIBD example has
been added. Examples with Set variables have been updated to
reflect the changes.
6) A number of bug fixes and changes in flatzinc interface to better
comply with minizinc 1.1. We have also added into minizinc
predicates networkflow that uses newly introduced JaCoP Network
Flow constraint.
7) A number of minor API changes to improve intuitiveness of use
(e.g. order of arguments in constructors).
8) The JaCoP guide has been updated to reflect the changes and additions
to the newest version. best regards, Core Developer Team |
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Last Updated on Wednesday, 01 September 2010 17:51 |
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Written by Radoslaw Szymanek
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Sunday, 12 September 2010 21:03 |
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Dear all, JaCoP was awarded a silver price in the fixed category among the elligible solvers for the awards in the Minizinc Challenge 2010. We did very well on benchmarks requiring use of diffn constraint usable in scheduling and placement problems. The incorrect answers reported by JaCoP was due to an unfortunate mismatch between the semantics of cumulative constraint in JaCoP and Minizinc challenge (see section 3.3.5 and equation 3.2 in JaCoP Guide) and lack of a safety check to make sure that automatic search uses all variables of the model. It is a pity as we lost a lot of points due to simple mistakes in flatzinc interface. Both issues are fixed in the current version of JaCoP available on sourceforge svn repository. We would like to thank Peter Stuckey and his team for all their work in running an interesting competition. It is gratifying to see that our focus on global constraints and modeling expressiveness is paying off. We hope that for the next year competition we will have even more problems with global constraints like network flow constraint, knapsack constraint, and geost constraint which have not been used yet in this year solver competition. We would also like to congratulate Geoffrey Chu who was not eligible for prize due to the rules of the competition. He at least deserves an applause for the efficiency of his entry. It really shows the potential of lazy clause learning technique. We will work on adding lazy clause generation to JaCoP so next year we can do even better then this year. best regards, Radoslaw Szymanek and Krzysztof Kuchcinski |
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Last Updated on Wednesday, 15 September 2010 14:17 |
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Written by Radoslaw Szymanek
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Tuesday, 22 June 2010 15:19 |
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Dear all, We are in the process of testing a very powerful network flow constraint. Before we release it in the next version of JaCoP we would like to test it more thoroughly. Feel free to contact us to get the newest development version of JaCoP to be able to try this constraint before it is available to the public. This constraint has been developed during the most recent student project. We would like to thank Robin Steiger for his hard work in this project. best regards Radoslaw Szymanek |
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Last Updated on Tuesday, 31 August 2010 14:01 |
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