This paper is concerned with emptyness of the essential spectrum, or equivalently compactness of the semigroup, for perturbations of selfadjoint operators that are bounded below (on an L2-space). For perturbations by a (nonnegative) potential we obtain a simple criterion for compactness of the semigroup in terms of relative compactness of the operators of multiplication with characteristic func...

In an L-topological space we present good definitions for local compactness, weak local compactness and relative local compactness. We obtain the equivalence of these properties in a Hausdorff space and we also obtain a one point compactification theorem.

creating and preserving large patches in land use configuration and satisfying compactness and contiguity in land use configuration are nature-prescribed and nature-inspired criteria that can be used in land use planning better that before. accompanying compactness and contiguity as the important landscape metrics in land use planning and land use configuration is close to applying proactive ap...

We investigate whether in the setting of approach spaces there exist measures of relative compactness, (relative) sequential compactness and (relative) countable compactness in the same vein as Kuratowski’s measure of compactness. The answer is yes. Not only can we prove that such measures exist, but we can give usable formulas for them and we can prove that they behave nicely with respect to e...

Compactness is introduced as a new method to search for the onset of the quark matter transition in relativistic heavy ion collisions. That transition supposedly leads to stronger compression and higher compactness of the source in coordinate space. That effect could be observed via pion interferometry. We propose to measure the compactness of the source in the appropriate principal axis frame ...

applying 2d algorithms for inverting the potential field data is more useful and efficient than their 3d counterparts, whenever the geologic situation permits. this is because the computation time is less and modeling the subsurface is easier. in this paper we present a 2d inversion algorithm for interpreting gravity data by employing a set of constraints including minimum distance, smoothness,...

The notion of near S *-compactness is introduced in L-topological spaces based on S *-compactness. Its properties are researched and the relations between it and other near compactness are obtained. Moreover many characterizations of near S *-compactness are presented. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, dist...