We relate the search number of an undirected graph G with the minimum and maximum of the progressive pebble demands of the directed acyclic graphs obtained by orienting (7. Towards this end, we introduce node-searching, a slight variant of searching, in which an edge is cleared by placing searchers on both of its endpoints. We also show that the minimum number of searchers necessary to node-sea...

Let be a simple and connected graph. A k-vertex separator [k-edge separator] is a subset of vertices [edges] whose deletion separates the vertex [edge] set of into two parts of equal cardinality, that are at distance greater than k in . Here we investigate the relation between the cardinality of these cutsets and the laplacian spectrum of . As a consequence of the study, we obtain the well-know...

Latin squares can be classified as odd or even according to the signs of the permutations given by their rows and columns. In this paper, the behaviour of the parities of a latin square under the action of the isotopy group (permuting rows, columns, and symbols) and the transformation group (interchanging rows, columns, and symbols) is analyzed. A rule is given that shows that the behaviour of ...

This paper deals with the well known classes of threshold and difference graphs, both characterized by separators, i.e. node weight functions and thresholds. We show how to maintain minimum the value of the separator when the input (threshold or difference) graph is fully dynamic, i.e. edges/nodes are inserted/removed. Moreover, exploiting the data structure used for maintaining the minimality ...

Polarization, solution-separator, charge transfer, and diffusion resistances of clean and used separator electrode assemblies were examined in microbial fuel cells using current–voltage curves and electrochemical impedance spectroscopy (EIS). Current–voltage curves showed the total resistance was reduced at low cathode potentials. EIS results revealed that at a set cathode potential of 0.3 V di...

In the present work we introduce a new are activity indicator, MAD and examine its characteristics by analyzing a set of successive three days' observations of a typical active region, AR2372. The computed MAD is compared with conventional activity indicator such as separator. It is found that (1) MAD traces very well the separator, (2) it singles out local discontinuity of magnetic eld lines a...

We give O( √ logn)-approximation algorithms for the Min UnCut, Min 2CNF Deletion, Directed Balanced Separator, and Directed Sparsest Cut problems. The previously best known algorithms give anO(logn)-approximation for Min UnCut [9], Directed Balanced Separator [17], Directed Sparsest Cut [17], and an O(logn log logn)approximation for Min 2CNF Deletion [14]. We also show that the integrality gap ...

The control of particle size distribution of fabricated alumina nanoparticles from general alumina that has a large geometric standard deviation (GSD) is studied. A thermophoretic separator was used to control the GSD of the fabricated alumina nanoparticles. Unevaporated particles and primary particles were separated to yield a small GSD for fabricated alumina nanoparticles. The fabricated alum...