Computations with finite closure systems and implications
Closure systems C ⊂ 2Mon a finite set M arise in many areas of discrete mathematics. They are conveniently encoded by either the family Irr(C) of meet irreducible closed sets, or by implicational bases Σ. We significantly improve six (partly little known) algorithms in order to settle the problems (a),(b),... (g) listed below. In particular, the algorithm LINCLOSURE, which is well known in relational database theory, is enhanced. It appears as a subroutine in three of our algorithms. Applications in database theory, matroid theory and algebra will be pointed out.
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