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(artificial intelligence)
A large knowledge-based system.

Cyc is a very large, multi-contextual knowledge base and inference engine, the development of which started at the Microelectronics and Computer Technology Corporation (MCC) in Austin, Texas during the early 1980s.

Over the past eleven years the members of the Cyc team, lead by Doug Lenat, have added to the knowledge base a huge amount of fundamental human knowledge: facts, rules of thumb, and heuristics for reasoning about the objects and events of modern everyday life.

Cyc is an attempt to do symbolic AI on a massive scale. It is not based on numerical methods such as statistical probabilities, nor is it based on neural networks or fuzzy logic. All of the knowledge in Cyc is represented declaratively in the form of logical assertions. Cyc presently contains approximately 400,000 significant assertions, which include simple statements of fact, rules about what conclusions to draw if certain statements of fact are satisfied, and rules about how to reason with certain types of facts and rules. The inference engine derives new conclusions using deductive reasoning.

To date, Cyc has made possible ground-breaking pilot applications in the areas of heterogeneous database browsing and integration, captioned image retrieval, and natural language processing.

In January of 1995, a new independent company named Cycorp was created to continue the Cyc project. Cycorp is still in Austin, Texas. The president of Cycorp is Doug Lenat.

The development of Cyc has been supported by several organisations, including Apple, Bellcore, DEC, DoD, Interval, Kodak, and Microsoft.

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This article is provided by FOLDOC - Free Online Dictionary of Computing (
References in periodicals archive ?
Semantic repositories such as OpenCyc that are developed to capture and represent common sense do not contain semantic relationships (e.g., whether two concepts are synonyms), and HowNet defines and analyzes Kansei words, but does not establish the connection between Kansei words, which makes it difficult to engage in further semantic reasoning.
The WSCC organizers will choose an annotation scheme that is (partly) based on an existing taxonomy, such as that given by OpenCyc (4) or DBPedia.
To that end, a combination of an array of complementary resources may be utilised, namely, corpora (e.g., Davies 2013) for finding correlations, and ontologies (e.g., OpenCyc (5)), Wordnet (6) (Miller 1995) and McRae's NORMS (7) for determining congruent properties and systematizing features as points or regions upon corresponding quality domains.
It tries to formalize common sense knowledge in an upper knowledge base for free as a carefully designed ontology named OpenCyc. OpenCyc can be downloaded in OWL format or directly be accessed as a RDF store using web services from Cycorp.
In addition to linking individual senses of a word to WordNet synsets (copies of which are hosted at, records at are linked to Library of Congress Subject Headings; records at OpenCyc (6); and linked internally at to translations for the various senses of the word (e.g., here is the URI for the word jeu, and here is the IRI (7) for piece de theatre, two French words which capture two of the senses connoted by the English play).
Others are Freebase (Google, 2011), OpenCyc (Cycorp Inc., 2013) or Factforge (Ontotext AD, 2012), which is especially interesting since it collects the data from the previous ones and offers it from a single endpoint.
In fact, the most famous ones are OpenMind (, Cyc or OpenCyc (, and Scone (
In this way one can annotate text on different levels of granularity including topic category of the whole document, extraction of facts mentioned in the text, named entity extraction and resolution (into some ontology such as, DBPedia, OpenCyc).
Ontology Entities Facts KnowItNow N/A 25,860 KnowItAll N/A 29,835 SUMO 20,000 60,000 OpenCyc 47,000 306,000 Cyc 500,000 5,000,000 WordNet 155,287 479,887 YAGO 1,056,638 5,000,000 YAGO2 9,800,000 120,000,000 HowNet 191,924 462,433 CCD 66,590 N/A CCE 2,000,000 N/A The ontology in [26] 822,135 5,237,520
The experimental data employ the data in "The Famous Knowledge Base for OpenCyc".
(7.) Thequery at find?str=surgery will, for example, return an XML document identifying the URI, which is the OpenCyc concept for the CycL collection #$Surgery.