A system for knowledge representation in a computer that can enable unrestricted natural language communication with a computer, comprising a database configured to store at least one table, the table configured to store associations between concepts in a text string and associated concept identifiers; and a builder interfaced with the database, the builder configured to construct a table that represents knowledge defined by a text string, the text string comprising (n) operands and (n−1) operators, by performing a process comprising the following steps: combining concepts in the text string into first order sub-concepts according to precedence defined by the operators, combining the first order sub-concepts into higher order concepts according to the precedence defined by the operators, repeating the steps until the higher order sub-concepts join to form a concept that represents the entire text string, and storing the concept, first order sub-concepts, and higher order sub-concepts in the database.