| Popis: |
In this paper we revisit the problem of computing the closure of a set of attributes, given a set of Armstrong dependencies. This problem is of main interest in logics, in the relational database model, in lattice theory and in Formal Concept Analysis as well. We consider here three main closure algorithms, namely Closure, LinClosure and Wild's Closure, which are combined with implication bases which may have different characteristics, among which being "minimal", e.g., the Duquenne-Guigues basis, and being "direct", e.g., the Canonical Basis and the D-basis. The impacts of minimality and directness on the closure algorithms are then deeply studied also experimentally. The results are extensively analyzed and propose a different and fresh look at computing the closure of a set of attributes. This paper has been submitted to the International Journal of Approximate Reasoning. |
