The Λ parameter on the anisotropic lattice, the spatial and temperature coupling constant gσ, gτ and their derivative with respaect to the the anisotropy parameter ξ are studied perturbatively for the class of improved actions, which cover tree level Symanzik's, Iwasaki's and QCDTARO's improved actions. The η(= gτ /gσ) becomes less than 1 for Iwasaki's and QCDTARO's action, which is confirmed n...

The cover tree data structure speeds up exact nearest neighbor queries over arbitrary metric spaces (Beygelzimer et al., 2006). This paper makes cover trees even faster. In particular, we provide 1. A simpler definition of the cover tree that reduces the number of nodes from O(n) to exactly n, 2. An additional invariant that makes queries faster in practice, 3. Algorithms for constructing and q...

Woodlands constitute the subsistence base of the majority of people in the Sudano-Sahelian zone (SSZ). Trees and grasses provide key ecosystem goods and services, including soil protection, fuelwood, food products and fodder. However, climate change in combination with rapidly increasing populations and altered land use practices put increasing pressure on the vegetation cover in this region. L...

In set system auctions, a single buyer needs to purchase services from multiple competing providers, and the set of providers has a combinatorial structure; a popular example is provided by shortest path auctions [1, 7]. In [3] it has been observed that if such an auction is conducted using first-price rules, then, counterintuitively, the buyer’s payment may go down if some of the sellers are p...

The intersection graph of a collection of trapezoids with corner points lying on two parallel lines is called a trapezoid graph. Using binary indexed tree data structure, we improve algorithms for calculating the size and the number of minimum vertex covers (or independent sets), as well as the total number of vertex covers, and reduce the time complexity from O(n) to O(n log n), where n is the...

We consider the problem of learning an unknown context-free grammar when the only knowledge available and of interest to the learner is about its structural descriptions with depth at most l. The goal is to learn a cover context-free grammar (CCFG) with respect to l, that is, a CFG whose structural descriptions with depth at most l agree with those of the unknown CFG. We propose an algorithm, c...

Various least core concepts including the classical least core of cooperative games are discussed. By a reduction from minimum cover problems, we prove that computing an element in these least cores is in general N P-hard for minimum cost spannning tree games. As a consequence, computing the nucleolus, the nucleon and the per-capita nucleolus of minimum cost spanning tree games is also N P-hard.

This paper focuses on finding a spanning tree of a graph to maximize the number of its internal vertices. We present an approximation algorithm for this problem which can achieve a performance ratio 4 3 on undirected simple graphs. This improves upon the best known approximation algorithm with performance ratio 5 3 before. Our algorithm benefits from a new observation for bounding the number of...

Given a tree and a set of weighted paths in that tree, the problem involves finding a minimum weighted subset of paths that covers all the vertices of the tree where each vertex is covered by a bounded number of paths, is scrutinized in this paper. This problem is referred to as the vertex covering by weighted paths on trees. All the necessary time and memory complexity with the algorithmic res...

The spatially explicit and mechanistic model TREEGRASS was used to test the effects of tree density, tree spatial distribution, and tree size distribution on radiation absorption, net primary production (NPP), and, water fluxes for a West African savanna . The model has previously been shown to adequately predict radiation absorption, production, and soil water balance in humid savannas . Using...