Formalized Common Knowledge

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Version 2.0 of the OpenCyc knowledge base is now available. See the OpenCyc KB v2.0 Release Notes for additional information.

OpenCyc Executable Downloads:

You can download the OpenCyc knowledgebase and inference system from SourceForge.

OpenCyc Ontologies (OWL Files):

The full OpenCyc content is available for download in the following OWL files:

Current Version

• Current version: opencyc-latest.owl.gz
  md5 checksum: 38bf8c9f5bfbbd1bda9989435d7da8b0

Archived Versions

2009 April 07

• Permanent IDs: opencyc-2009-04-07.owl.gz
  md5 checksum: 5fb3a25fb97d24312974bcf29675fae7
• Human-readable IDs: opencyc-2009-04-07-readable.owl.gz
  md5 checksum: 7ff7874b550dbdb27811ed50f240dcc4

2008 June 10

• Permanent IDs: opencyc-2008-06-10.owl.gz
  md5 checksum: 5bc2cb422e9c4528392019387dcd27e2
• Human-readable IDs: opencyc-2008-06-10-readable.owl.gz
  md5 checksum: fead1ed9ddc93ddfee20e980af6ae3ae

Last updated: April 20, 2009