Combining temporal processing and textual entailment to detect temporally anchored events

A system for extraction of events comprising:

• memory which stores an annotated collection of natural language text documents in which predicates and respective arguments of the predicates are identified, at least one of the arguments of each identified predicate comprising a temporal expression which is normalized with respect to a reference date of a respective document;
• a filtering component which, based on an input query which includes a topic and date information which defines a date range, identifies a collection of excerpts from the annotated collection of documents, each excerpt including an argument, which is based on the topic, and a normalized reference to a date which matches the defined date range of the query;
• a textual entailment component which identifies excerpts in the collection that are linked together by entailment relationships;
• an event set identification component which identifies a plurality of sets of events in the collection of excerpts, each set of events comprising a plurality of the excerpts in the collection that are linked together by entailment relationships;
• and
• a processor which implements the components.

A method for generating a chronology comprising:

• receiving a collection of news articles each article identifying a reference date;
• receiving a query which includes a topic and date information which defines a date range;
• natural language processing the articles to identify excerpts, each of the excerpts including a predicate and arguments of the predicate, a first of the arguments of the predicate matching at least part of the topic, a second of the arguments of the predicate including a temporal expression which, when normalized with respect to the reference date of the article, matches the date information of the query;
• partitioning the excerpts into sets of events, each set of events including excerpts that are linked together by entailment relationships;
• for each of a plurality of the sets of events, identifying a main event based on an excerpt which does not entail any of the other excerpts in the set;
• forming a chronology based on the main events;
• and
• wherein at least one of the processing of the articles, partitioning excerpts, identifying main events, and forming a chronology is performed with a computer processor.