Analyzing the worst-case complexity of the k-level in a planar arrangement of n curves is a fundamental problem in combinatorial geometry. We give the first subquadratic upper bound (roughly O(nk1 2=3s)) for curves that are graphs of polynomial functions of an arbitrary fixed degree s. Previously, nontrivial results were known only for the case s = 1 and s = 2. We also improve the earlier bound...

For a graph property $$\varPi $$ , Subgraph Complementation to is the problem find whether there subset S of vertices input G such that modifying by complementing subgraph induced results in satisfying . We prove T-free graphs NP-Complete, for T being tree, except 41 trees at most 13 (a if it does not contain any copies T). This result, along with 4 known polynomial-time solvable cases (when pa...

Shortleaf pine (Pinus echinata Mill.) seed production was monitored for 4 yr in stands harvested by a range of evenand uneven-aged reproduction cutting methods. The fifty-two 35–40 ac stands were distributed throughout the Ouachita Mountains from central Arkansas to eastern Oklahoma. Seed crops were characterized as good, poor, poor, and bumper, averaging 109,000, 18,000, 5,000, and 379,000 sou...

Ceratocystis wilt on eucalyptus, caused by Ceratocystis fimbriata, was first recognized in 1997 in the state of Bahia, Brazil, but is now known in five other states and in four other countries. C. fimbriata is a native, soilborne pathogen in some parts of Brazil but we hypothesized that genotypes of the pathogen have been moved among plantations in rooted cuttings collected from diseased trees ...

Most integer programming problems can be formulated in several ways. Some formulations are better suited for solution by exact methods, because they have either (i) a strong LP relaxation, (ii) few symmetries in the solution space, or both. However, solving one formulation, we can often branch and/or add cutting planes which are implicitly based on variables of other formulations, working in fa...

The effects of litter and humus layers on the occurrence of ectomycorrhizal sporocarps in 64 plots in six stands of Pinus sylcestris were studied. In 1990, litter and humus layers and herbaceous vegetation were removed ('sod-cutting') in plots in stands of Pinus sylvestris of different age. Removed litter and humus were added on to existing ectorganic layers ( 'sod-addition') in plots in young ...

Despite the importance of financial outcomes to stand-level forest management decision-making, long-term assessments are rare. We compared quality and value mixed, northern conifer (Picea–Abies–Tsuga) stands in Maine, USA, treated with a range silvicultural systems exploitive cuttings for 65 years. Ten replicated treatments — single-tree selection uniform shelterwood systems, commercial clearcu...

Miombo woodlands are crucial to the livelihoods of rural people throughout southern, eastern and central Africa. This paper describes a dynamic simulation model of key ecological processes in miombo and examines the ecological and economic impacts of various forms of management. The model shows that removing harvestable trees and reducing the level of grazing by livestock causes an increase in ...

A degraded oak savanna in southwestern Wisconsin is being restored using intensive cutting of undesirable shrubsbuckthorn (Rhamnus cathartica), prickly ash (Zanthoxylum americanum), honeysuckle (Lonicera spp.)-and selective removal of trees that are crowding the open-grown bur (Quercus macrocar/Ja) and white (Q. alba) oaks. Land use records and historic aerial photographs have been used to guid...