The disclosure describes a method and apparatus for maintaining groupings and relationships of propositions associated with a knowledge base. In one embodiment, the method includes providing multiple microtheories to form a knowledge base. Each microtheory includes multiple propositions. An mt label is provided for each microtheory. A proposition label is provided for each proposition. The proposition label for a specific proposition is compared with the microtheory labels in response to a transaction request. Microtheory labels that have a common element with the proposition label are determined. In another embodiment, the method includes providing multiple microtheories, providing an mt label for each microtheory, and initializing tags for first and second microtheories to a clean value. In one embodiment, the apparatus may include one or more storage devices and a tag processing logic.