1. A method performed by at least one computer processor, the method comprising: (1) storing data representing a plurality of classes and a plurality of instances in a bijective-set memory; (2) storing data representing class membership relationships between the plurality of classes and the plurality of instances in the bijective-set memory; (3) receiving data representing a query, wherein the query does not specify any table; (4) identifying an operation specified by the query; (5) identifying an operand specified by the query; (6) executing the query, comprising: (6) (a) identifying a table to be searched, based on the query; and (6) (b) performing the operation on the operand, including searching the identified table, to produce an output; wherein (1) comprises storing the data representing the plurality of classes and the plurality of instances in a single table in the bijective-set memory, and wherein (2) comprises storing the data representing the class membership relationships between the plurality of classes and the plurality of instances in the single table in the bijective-set memory.
1. A method performed by at least one computer processor, the method comprising: (1) storing data representing a plurality of classes and a plurality of instances in a bijective-set memory; (2) storing data representing class membership relationships between the plurality of classes and the plurality of instances in the bijective-set memory; (3) receiving data representing a query, wherein the query does not specify any table; (4) identifying an operation specified by the query; (5) identifying an operand specified by the query; (6) executing the query, comprising: (6) (a) identifying a table to be searched, based on the query; and (6) (b) performing the operation on the operand, including searching the identified table, to produce an output; wherein (1) comprises storing the data representing the plurality of classes and the plurality of instances in a single table in the bijective-set memory, and wherein (2) comprises storing the data representing the class membership relationships between the plurality of classes and the plurality of instances in the single table in the bijective-set memory. 9. The method of claim 1 , wherein the operation comprises a difference operation.