Concordia - Roman goddess of agreement. Concordance searcher - tool for translators who need their translations to "agree" with one standard.

Concordia is a C++ library for fast text lookup in large corpora. It uses a RAM stored index, which takes up approximately 600MB of memory for a corpus of 2 million sentences. It is based on the idea of a suffix array, enhanced by the presence of other auxiliary data structures.

The effects are stunning - Concordia is able to do simple substring lookup at the pace of 5000 queries per second (on personal PC) - a speed which can not be achieved by any other search library.

Moreover, Concordia can perform its own "concordia search". For a given input sentece, all substring matches covering this sentence are retrieved.

This project now contains fully functional Concordia search library. In the near future, it will be extended by concordia-server: ligthweight, robust web server providing corpora search functionalities.


If you are planning to use this software in scientific research, please cite the following paper:

R. Jaworski: "Approximate sentence matching and its applications to corpus-based research", The Future of Information Sciences: e-Institutions, Openness, Accessibility and Preservation, pp. 21-30 (keynote paper), 2015 [docx].


  title={Approximate sentence matching and its application in corpus-based research},
  author={Jaworski, Rafa{\l}},
  journal={The future of Information Sciences: e-Institutions,
           Openness, Accessibility and Preservation},
  publisher={Department of Information and Communication Sciences,
             Faculty of Humanities and Social Sciences, University of Zagreb}


Concordia makes use of the following Open Source projects:

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