Extending the Maximum Entropy Approach to Variable Strength Defaults

A generalisation of the maximum entropy (ME) approach to default reasoning 7,8] to cater for variable strength defaults is presented. The assumptions on which the original work was based are reviewed and revised. A new algorithm is presented that is shown to compute the ME-ranking under these more general conditions. The limitations of the revised approach are discussed and a test for the uniqueness of the ME-solution is given. The ME-solutions to several illustrative examples of default reasoning are given, and the approach is shown to handle them appropriately. The conclusion is that the ME-approach can be regarded as providing a benchmark theory of default reasoning against which default intuitions and other default systems may be assessed.