Let N = f1; : : : ; ng be a nite set of players and K N the complete graph on the node set N f0g. Assume that the edges of K N have nonnegative weights and associate with each coalition S N of players as cost c(S) the weight of a minimal spanning tree on the node set S f0g. Using reduction to EXACT COVER BY 3-SETS, we exhibit the following problem to be… (More)
The nucleon is introduced as a new allocation concept for non-negative cooperative n-person transferable utility games. The nucleon may be viewed as the multiplicative analogue of Schmeidler's nucleolus. It is shown that the nucleon of (not necessarily bipartite) matching games can be computed in polynomial time.
We predict the existence of low-frequency nonlocal plasmons at the vacuum-surface interface of a superlattice of N graphene layers interacting with conducting substrate. We derive a dispersion function that incorporates the polarization function of both the graphene monolayers and the semi-infinite electron liquid at whose surface the electrons scatter… (More)
We investigate the localization of charged particles by the image potential of spherical shells, such as fullerene buckyballs. These spherical image states exist within surface potentials formed by the competition between the attractive image potential and the repulsive centripetal force arising from the angular motion. The image potential has a power law… (More)
With the advent of recent generations of Field Pro-grammable Gate Arrays, it has become possible to use computing resources more eeciently by dynamically reconnguring hardware (during run-time). This is achieved by reassigning computation modules or tasks to unused cells. For a given problem consisting of a set of tasks, possibly with partial order… (More)
In this paper we study the complexity of an Inverse Shortest Paths Problem (ISPP). We show that the problem is intractable even in very restricted cases. In particular, we prove that the ISPP is NP-complete in the planar case. Furthermore, we give a characterization of the class of graphs G d of given distances for which the ISPP is tractable: we give… (More)
The bin packing problem is one of the classical NP-hard optimization problems. Even though there are many excellent theoretical results, including polynomial approximation schemes, there is still a lack of methods that are able to solve practical instances optimally. In this paper, we present a fast and simple generic approach for obtaining new lower… (More)
A tree t-spanner of a graph G is a spanning subtree T of G in which the distance between every pair of vertices is at most t times their distance in G. Spanner problems have received some attention, mostly in the context of communication networks. It is known that for general unweighted graphs, the problem of deciding the existence of a tree t-spanner can… (More)