On attribute reduction in concept lattices: The polynomial time discernibility matrix-based method becomes the CR-method

We eliminate unnecessary computations of attribute discernibility sets in discernibility matrix-based methods (DM-methods) of attribute reduction in concept lattices. We obtain a polynomial time algorithm we call a Skim DM-method. The Skim DM-method however is merely slightly different from the standard clarification and reduction (CR-method). This result enables us to express a relationship of the CR-method and the DM-methods: the DM-methods are basically the CR-method with up to an exponential amount of unnecessary computations. Additionally, we experimentally evaluate the Skim DM-method in comparison with the CR-method. (C) 2019 Elsevier Inc. All rights reserved.