Execution of semantic queries using rule expansion

A system for answering a semantic query, the system comprising:

• a semantic query engine that receives the semantic query, the semantic query comprising a first rule that comprises one or more constituent terms that comprise, or are reducible to, one or more grounded terms in a relational database;
• a relational query generator that expands the semantic query into an expanded semantic query by replacing said first rule with its constituent terms, said relational query generator generating a relational query based on said expanded semantic query and submitting said relational query to said relational database;
• and
• said relational database, which stores tables corresponding to said grounded terms, each of said tables corresponding to a predicate and defining subject and object pairs that are related by said predicate, said relational database providing a result in response to said relational query by performing relational operations on said tables.

A method of processing a first query that includes a first rule, the method comprising:

• using a processor to perform acts comprising:
• receiving said first query;
• determining that said first query comprises said first rule, wherein said first rule comprises, or is reducible to, a set of grounded terms comprising a first grounded term and a second grounded term;
• expanding said first query into a second query that comprises said first grounded term and said second grounded term;
• generating a third query based on said second query, said first query being a semantic query, said third query being a relational query that calls for relational operation on tables or views, in a relational database, that correspond to said first grounded term and said second grounded term;
• receiving a first result of said third query from said relational database;
• and
• providing said first result, or a second result based on said first result, to a person.