We study the computational complexity of several problems connected with the problems of finding a maximal distance-k matching of minimum cardinality or minimum weight. We introduce the class of k-equimatchable graphs which is an edge analogue of k-equipackable graphs. We prove that the recognition of k-equimatchable graphs is co-NP-complete for any fixed k ≥ 2. We provide a simple characteriza...

A graph G is well-covered if all its maximal independent sets are of the same cardinality. Assume that a weight function w is defined on its vertices. Then G is w-well-covered if all maximal independent sets are of the same weight. For every graph G, the set of weight functions w such that G is w-well-covered is a vector space, denoted WCW (G). Let B be a complete bipartite induced subgraph of ...

In many combinatorial situations there is a notion of independence of a set of points. Maximal independent sets can be easily constructed by a greedy algorithm, and it is of interest to determine, for example, if they all have the same size or the same parity. Both of these questions may be formulated by weighting the points with elements of an abelian group, and asking whether all maximal inde...

It is well known that electrons passing through a magnetic undulator emit partially coherent radiation: `Undulator Synchrotron Radiationa. Radiation from electrons, entering the undulator at random, adds incoherently. If the electron beam is periodically modulated (bunched) to pulses shorter than the radiation wavelength, electrons radiate in phase with each other, resulting in super-radiant em...

background: many studies have been conducted to assess the indoor air quality (iaq) of buildings throughout the world because it is closely related to comfort, safety and work productivity of occupants. however, there is still lack of available literature about iaq in tropical buildings that apply radiant cooling systems in conditioning the indoor air. methods: this paper reports the results ob...

OBJECTIVE To compare the efficacy of forced-air warmers and radiant heaters on rewarming after cardiac surgery in a prospective randomized study. METHODS Fifty male patients who had undergone coronary artery bypass graft surgery were studied. The control group (Gr. C, n=10) was nursed under a standard hospital blanket. Two groups were treated with forced-air warmers: WarmTouch 5700 (Gr. WT, n...

In Gaussian maximum likelihood classification, the mean vector and covariance matrix are usually estimated from training samples. When the training sample size is small compared to dimensionality, the sample estimates, especially the covariance matrix becomes highly variable and consequently, the classifier performs poorly. In particular, if the number of training samples is less than dimension...