The performance of data-parallel algorithms for spatial operations using data-parallel variants of the bucket PMR quadtree, R-tree, and R-tree spatial data structures is compared. The studied operations are data structure build, polygonization, and spatial join in an application domain consisting of planar line segment data (i.e., Bureau of the Census TIGER/Line les). The algorithms are impleme...

This paper presents several distributed and decentralized strategies used for token traversal in spanning forest over DTMs. DTMs or Delay Tolerant Mobile ad hoc networks are characterized by some undesirable behaviors like the disappearance of mobile devices, connection disruptions, network partitioning, etc. Providing efficient communications in DTMs is a very challenging issue. Techniques bas...

Equational tree automata provide a powerful tree language framework that facilitates to recognize congruence closures of tree languages. In the paper we show the emptiness problem for AC-tree automata and the intersection-emptiness problem for regular AC-tree automata, each of which was open in our previous work [20], are decidable, by a straightforward reduction to the reachability problem for...

Tree projections provide a mathematical framework that encompasses all the various (purely) structural decomposition methods that have been proposed in the literature to single out classes of nearly-acyclic (hyper)graphs, such as the tree decomposition method, which is the most powerful decomposition method on graphs, and the (generalized) hypertree decomposition method, which is its natural co...

In this paper a new approach to evolutionary controlled creation of electronic circuit connection topology is proposed. Microwave circuits consisting of a tree like connection of ideal transmission lines are considered. Assuming that a reasonable number of transmission lines in a tree network ranges from 10 to 100, the number of connection combinations is immense. From the engineering practice ...

A vertex-colored graph G is rainbow vertex-connected if two vertices are connected by a path whose internal vertices have distinct colors. The rainbow vertex-connection number of a connected graph G, denoted by rvc(G), is the smallest number of colors that are needed in order to make G rainbow vertex-connected. If for every pair u, v of distinct vertices, G contains a vertex-rainbow u−v geodesi...

Case reports of transdiaphragmatic fistulas connecting subphrenic collections and empyemas are uncommon. We report the rare complication of a fistulous connection between a subphrenic collection and the bronchial tree.

The notion of Steiner visibility graphs is introduced. Their applicability in connection with the construction of good quality suboptimal solutions to the Euclidean Steiner tree problem with obstacles is discussed. Polynomial algorithms generating Steiner visibility graphs are described.

We present runt pruning, a new clustering method that attempts to find modes of a density by analyzing the minimal spanning tree of a sample. The method exploits the connection between the minimal spanning tree and nearest neighbor density estimation. It does not rely on assumptions about the specific form of the data density (e.g., normal mixture) or about the geometric shapes of the clusters,...