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title: GECODE - An open, free, efficient constraint solving toolkit
description: Gecode is an open source C++ toolkit for developing constraint-based systems and applications. Gecode provides a constraint solver with state-of-the-art performance while being modular and extensible.
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  <h2>Gecode</h2>

  <p>
    Gecode is an open source C++ toolkit for developing constraint-based systems
    and applications. Gecode provides a constraint solver with
    state-of-the-art performance while being modular and extensible.
    Gecode is:
  </p>

  <dl>
  <dt>open</dt>
  <dd>Gecode is radically open for programming: it can be 
      easily interfaced to other
      systems. It supports the programming of new constraints, branching strategies, 
      and search engines. New variable domains can be programmed at the same
      level of efficiency as the variables
      that come predefined with Gecode.</dd>
  
  <dt>comprehensive</dt>
  <dd>Gecode has a comprehensive set of features: constraints over integers, Booleans, sets, and floats (it implements more than 70 constraints from the <a href="http://www.emn.fr/z-info/sdemasse/gccat/">Global Constraint Catalog</a> and many more on top); C++ modeling layer; advanced branching heuristics (accumulated failure count, activity); many search engines (parallel, interactive graphical, restarts); automatic symmetry breaking (LDSB); no-goods from restarts; MiniZinc support; and many more.
  </dd>  
  <dt>efficient</dt>
  <dd>Gecode offers excellent performance with respect to both runtime and 
      memory usage. It won <em>all</em>
      gold medals in <em>all</em> categories at the MiniZinc Challenges from 2008 to 2012:
     <a href="http://www.g12.cs.mu.oz.au/minizinc/challenge2012/results2012.html">2012</a>,
     <a href="http://www.g12.cs.mu.oz.au/minizinc/challenge2011/results2011.html">2011</a>,
     <a href="http://www.g12.cs.mu.oz.au/minizinc/challenge2010/results2010.html">2010</a>,
     <a href="http://www.g12.cs.mu.oz.au/minizinc/challenge2009/results2009.html">2009</a>, and
     <a href="http://www.g12.csse.unimelb.edu.au/minizinc/results.html">2008</a>.</dd>
  <dt>documented</dt>
  <dd>Gecode comes with both complete tutorial (more than 500 pages) and complete reference documentation 
      that allows users to focus on different modeling and programming
      tasks with Gecode.</dd>
  <dt>free</dt>
  <dd>Gecode is distributed under the MIT <a href="license.html"
      >license</a> and is
      <a href="http://directory.fsf.org/gecode.html">
      listed as free software by the FSF</a>. All of its parts
      including reference documentation, implementations of global constraints,
      and examples are available as
      source code for <a href="download.html">download</a>.</dd>
  <dt>portable</dt>
  <dd>Gecode is implemented in C++ that carefully follows the C++ standard.
      It can be compiled with modern C++ compilers and runs on
      a wide range of machines.</dd>
  <dt>parallel</dt>
  <dd>Gecode complies with reality in that it exploits the multiple cores
      of today's commodity hardware for parallel search, giving an already 
      efficient base system an additional edge.</dd>
  </dl>
  <dt>tested</dt>
  <dd>Gecode uses a test suite with more than 50000 different test cases reaching a test coverage close to 100%.</dd>
  </dl>