5. Discussion

The TMS-CD relies solely on the structure of the belief network to decide which beliefs to keep and which beliefs to reject when faced with a contradiction. The only point at which domain dependent information might play a role is when the strength of two competing beliefs are so close that their difference does not exceed the assigned d value and an external decision process is called. The inclusion of an external decision process in the TMS-CD provides the option of making use of domain dependent information that Doyle [2] had suggested if it is available. If no domain dependent information is available that would help an external decision process, one of the conflicting beliefs could be chosen randomly. This would allow for a completely domain independent implementation of the TMS-CD. To remain true to Cognitive Dissonance Theory, however, the final decision should probably be postponed until new relevant information is available or a decision is unavoidable.

The TMS-CD updates the belief network every time a new belief is inferred whether it causes a contradiction or not. Doyle's TMS only has to update the belief network when a contradiction is found. Although the TMS must update more often, changes made to the belief network should be more gradual and lead to less variation in system behavior. These predictions should be verified through empirical research in the future.

The TMS-CD proposed here is based on Doyle's [2] TMS, which was the first domain-independent justification-based truth maintenance system (JTMS). De Kleer [1] designed an assumption-based truth maintenance system (ATMS) which maintains an explicit list of assumption sets that support the derivation of each belief in the network. The ATMS allows the reasoning system to rapidly select a context (set of assumptions) and reason about only the beliefs that are true within that context.

The ATMS might be very useful when combined with Cognitive Dissonance Theory if a different definition is given to strength than has been used here. Instead of calculating the strength of two conflicting beliefs, we calculate the strength of the dissonance caused by a particular context. This could give us an ordering of the possible contexts, so we choose the context that results in the least amount of dissonance. Future research could look into the possibility of an ATMS-CD.

Back | Home | Next