On attribute reduction in concept lattices: Methods based on discernibility matrix are outperformed by basic clarification and reduction

Several recent papers have studied the problem of attribute reduction in concept lattices by using a discernibility matrix in various extensions of formal concept analysis. We recall the clarification and reduction method by Ganter & Wille and show that it is strictly superior to the methods based on discernibility matrix. Consequently, we show how to adapt the clarification and reduction method to the extensions of formal concept analysis considered in the recent papers.