flatzinc.html

---
layout: default
title: GECODE flatzinc
headline: FlatZinc
---

{% assign GECODESTAMP = site.data.versions["gecodestamp"] %}
{% assign GECODECLEARDATE = site.data.versions["gecodecleardate"] %}
{% assign GECODEFLATZINCVERSION = site.data.versions["gecodeflatzincversion"] %}

  <p>
    FlatZinc is a low-level modelling language for constraint problems. It is 
    designed to be easily interfaceable to constraint solvers (like Gecode). 
    For more information on FlatZinc, please refer to
    <a href="http://www.minizinc.org/">
    the MiniZinc pages of the G12 project.
    </a>
  </p>

  <p>
    We provide a parser that reads a FlatZinc model from a file, and returns a 
    Gecode Space object that represents the model. We also provide a simple 
    front-end, an executable program that reads a FlatZinc model and prints 
    the solution (if any) on the standard output.
  </p>

  <h2>FlatZinc for Gecode</h2>

  <p>
    Starting with Gecode version 3.2.0, the FlatZinc interpreter for Gecode
    is part of the standard Gecode distribution.
    Please check our <a href="download.html">download pages</a> for more 
    information on how to get a copy of Gecode. Source packages as well
    as binary packages are available.
  </p>
  
  <p>
    The FlatZinc interpreter that ships with Gecode version {{ GECODESTAMP }}
    supports the FlatZinc language and MiniZinc global constraint definitions
    of MiniZinc version {{ GECODEFLATZINCVERSION }}.
  </p>

  <h2>Running the parser</h2>

  <p>
    The executable is called fzn-gecode.  You can run it with the -help switch to get 
    an overview of how to invoke it:
  </p>

<pre>
$ fzn-gecode -help
Gecode FlatZinc interpreter
 - Supported FlatZinc version: {{ GECODEFLATZINCVERSION }}


Gecode configuration information:
 - Version: {{ GECODESTAMP }}

 - Variable types: BoolVar IntVar SetVar FloatVar
 - Trigonometric and transcendental float constraints: enabled
 - Thread support: enabled (8 processing units)
 - Gist support: enabled

Options for Gecode/FlatZinc:
        -help, --help, -?
                print this help message
        -n (unsigned int) default: 1
                number of solutions (0 = all)
        -p (double) default: 1
                number of threads (0 = #processing units)
        -c-d (unsigned int) default: 8
                recomputation commit distance
        -a-d (unsigned int) default: 2
                recomputation adaption distance
        -a (optional: false, 0, true, 1) default: false
                return all solutions (equal to -solutions 0)
        --free (optional: false, 0, true, 1) default: false
                no need to follow search-specification
        -decay (double) default: 1
                decay factor
        -node (unsigned int) default: 0
                node cutoff (0 = none, solution mode)
        -fail (unsigned int) default: 0
                failure cutoff (0 = none, solution mode)
        -time (unsigned int) default: 0
                time (in ms) cutoff (0 = none, solution mode)
        -interrupt (optional: false, 0, true, 1) default: true
                whether to catch Ctrl-C (true) or not (false)
        -r (int) default: 0
                random seed
        -restart (none, constant, linear, luby, geometric) default: none
                restart sequence type
        -restart-base (double) default: 1.5
                base for geometric restart sequence
        -restart-scale (unsigned int) default: 250
                scale factor for restart sequence
        -mode (solution, stat, gist) default: solution
                how to execute script
        -s (optional: false, 0, true, 1) default: false
                emit statistics
        -o (string) default: NONE
                file to send output to
</pre>

  <h2>Global constraint definitions for MiniZinc</h2>

  <p>
    The MiniZinc-to-FlatZinc converter provided by the G12 project can produce 
    specialized FlatZinc that is targeted at a certain solver. Gecode/FlatZinc 
    provides suitable definitions of global constraints in the directory 
    <tt>mznlib</tt>. This directory is located in the Gecode directory 
    installed in your program files folder (if you use the Windows binary 
    package), in <tt>/usr/local/share/gecode</tt> if you use the Mac OS 
    binary package, or in &lt;prefix&gt;/share/gecode if you installed 
    Gecode from the sources.
  </p>

  <p>
    In order to make the MiniZinc-to-FlatZinc converter aware of these global 
    constraint definitions, you can either
  </p>
  
  <ul>
  <li> copy the <tt>mznlib</tt> directory into the <tt>lib/minizinc</tt> 
    directory of your MiniZinc installation, rename it to <tt>gecode</tt>, and 
    use the <tt>-G gecode</tt> flag of <tt>mzn2fzn</tt>;</li>
  <li> or use the <tt>-I</tt> flag of <tt>mzn2fzn</tt> with the complete 
    path to the <tt>mznlib</tt> directory;</li>
  <li> or use the <tt>mzn-gecode</tt> script, which will invoke 
    <tt>mzn2fzn</tt> with the correct library paths and directly pass the 
    resulting FlatZinc on to the Gecode FlatZinc interpreter.</li>
  </ul>

  <h2>FlatZinc parser skeleton</h2>

  <p>
    We also provide the source code of the Gecode FlatZinc parser, stripped of 
    all Gecode-specific code. You can use it as a starting point for your own 
    FlatZinc interpreter.
  </p>

  <p>
    The source code archive (compatible with FlatZinc 1.5) is available here:
  </p>
  
  <ul>
    <li><a href="download/flatzinc_skeleton-1.3.zip">flatzinc_skeleton-1.3.zip</a></li>
  </ul>

  <p>
    The archive contains a README file that explains how to adapt and compile 
    the code. If you have any questions, please contact <a 
    href="mailto:tack@gecode.org">tack@gecode.org</a>.
  </p>

  <h2>MiniZinc with Search Combinators</h2>

  <p>
    We have extended the Gecode FlatZinc interpreter with support for 
    <em>Search Combinators</em>, a new, powerful modeling language for search 
    heuristics. Search Combinators are explained in detail in
    <a href="paper.html?id=SchrijversEtAl:CoRR:2012">this paper</a>.
  </p>

  <p>
    You can download an archive with the source code and pre-built binaries 
    for Windows, Mac OS, and Linux. The archive contains a README and some 
    examples to get you started.
  </p>
  
  <ul>
    <li><a href="download/searchcombinators-0.9.3.zip">searchcombinators-0.9.3.zip</a></li>
    <li><a href="download/searchcombinators-0.9.3.tgz">searchcombinators-0.9.3.tgz</a></li>
  </ul>

  <p>
    If you have any questions, please contact <a 
    href="mailto:Guido Tack <tack@gecode.org>">Guido Tack <tack@gecode.org></a>.
  </p>

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