Well-structured transition systems provide the right foundation to compute a finite basis of the set of predecessors of the upward closure of a state. The dual problem, to compute a finite representation of the set of successors of the downward closure of a state, is harder: Until now, the theoretical framework for manipulating downward-closed sets was missing. We answer this problem, using ins...

Bovet, Crescenzi, and Silvestri ( 1992, 1995), and independently Vereshchagin ( 1994), showed that many complexity classes in the polynomial time setting are leaf language classes, i.e. classes which are determined by two disjoint languages. They gave many examples but they did not characterize the set of leaf language classes. This will be done in &his paper. It will be shown that the set of l...

This paper describes the three Fast Downward Aidos portfolios we submitted to the Unsolvability International Planning Competition 2016. All three Aidos variants are implemented in the Fast Downward planning system (Helmert 2006). We use a pool of techniques as a basis for our portfolios, including various techniques already implemented Fast Downward, as well as three newly developed techniques...

We study several geometric set cover problems in which the goal is to compute a minimum cover of a given set of points in Euclidean space by a family of geometric objects. We give a short proof that this problem is APX-hard when the objects are axis-aligned fat rectangles, even when each rectangle is an ǫ-perturbed copy of a single unit square. We extend this result to several other classes of ...

the normalized full gradient (nfg) method defined by berezkin (1967, 1973 and 1998) is used for downward continuation maps. analytical downward continuation is a method to estimate the field closer to the source and consequently results in a better resolution of underground rock distribution. however, the usefulness of this process is limited by the fact that the operation is extremely sensitiv...

A great challenge for data mining techniques is the huge space of potential rules which can be generated. If there are tens of thousands of items, then potential rules involving three items number in the trillions. Traditional data mining techniques rely on downward-closed measures such as support to prune the space of rules. However, in many applications, such pruning techniques either do not ...

The downward closure of a language L of words is the set of all (not necessarily contiguous) subwords of members of L. It is well known that the downward closure of any language is regular. Although the downward closure seems to be a promising abstraction, there are only few language classes for which an automaton for the downward closure is known to be computable. It is shown here that for sta...