Name : GEM++ Description : A Graph Extraction and Matching C++ software Developers : Julien Lerouge, Maroua Hammami, Pierre Héroux, Sébastien Adam Contributors : Pierre Le Bodic Contact : gem-contact@litislab.eu

GEM++ is a software implementing several graph matching approaches, using binary linear programming. It is composed of five main executables and one common library :

• GEM++dist is a command-line executable, that computes an edit distance between two graphs;
• GEM++sub is a second command-line executable, that searches a subgraph isomorphism between a pattern graph and a target graph;
• GEM++multidist and GEM++multisub provides the same functionalities as the two former commands, but for sets of graphs (they compute a distance matrix);
• GEM++gui is a graphical user interface that lets the user load graphs, select subgraphs, set the parameters of the matching algorithm and see its results.
• libGEM++.so / GEM++.dll is the shared library that provides methods to extract graphs from various data, to load and save graph and weights files, and to solve a graph matching problem.

Here are the main functionnalities of GEM++ :

• Supports undirected or directed, labeled or unlabeled graphs, stored in the following graph file formats :
  • GML (Graph Modeling Language)
  • GXL (Graph eXchange Language)
• Supports the weighting of vertices and edges labels, with feature weights configuration files (see weights);
• Provides different matching algorithms, solved by Integer Programming, especially Binary Linear Programming (BLP) :
  • Graph edit distance (GED), that can be used in its exact form or with following approximations :
    • Upper-bound, reducing the number of possible matchings by forbidding some substitutions,
    • Bipartite graph matching [1];
  • Subgraph isomorphism, that comes with different levels of tolerance :
    • Exact subgraph isomorphism,
    • Substitution-tolerant subgraph isomorphism [2] [3],
    • Error-tolerant subgraph isomorphism [4]
• Supports the following integer programming solvers :
  • IBM CPLEX Optimizer
  • Gurobi Optimizer
  • GLPK

If you used GEM++ software in any published work, you are highly encouraged (though not required) to cite the following paper:

• J. Lerouge, P. Le Bodic, P. Héroux and S. Adam, "GEM++: A Tool for Solving Substitution-Tolerant Subgraph Isomorphism" , Proceedings of GbRPR 2015 10th IAPR-TC-15 International Workshop. LNCS Vol. 9069. Springer, 2015.

Here are some of our references :

• [1] Kaspar Riesen and Horst Bunke. Approximate graph edit distance computation by means of bipartite graph matching. Image and Vision Computing, 27(7):950–959, 2009.
• [2] Pierre Le Bodic, Hervé Locteau, Sébastien Adam, Pierre Héroux, Yves Lecourtier, and Arnaud Knippel. Symbol detection using region adjacency graphs and integer linear programming. In Proceedings of the International Conference on Document Analysis and Recognition (ICDAR'09), pages 1320–1324. IEEE, 2009.
• [3] Pierre Le Bodic, Pierre Héroux, Sébastien Adam, and Yves Lecourtier. An integer linear program for substitution-tolerant subgraph isomorphism and its use for symbol spotting in technical drawings. Pattern Recognition, 45(12):4214–4224, 2012.
• [4] Julien Lerouge, Maroua Hammami, Sébastien Adam, and Pierre Héroux. Minimum cost subgraph matching using a binary linear program. Pattern Recognition Letters, 2015. Preprint submitted to Elsevier.

GEM++ has been developed with the following softwares and tools :

• Qt Open-Source SDK, a multi-plateform object-oriented C++ framework, developed by The Qt Company Ltd and released under the GNU LGPL,
• QgarLib, a document analysis C++ library, developed by LORIA and released under the GNU LGPL.

GEM++ is the property of LITIS lab (c) 2013-2015 LITIS.

GEM++ is a free software, distributed under the terms of the CeCILL version 2.1 license (see LICENSE.en file).