Trees and Extensive Forms

This paper addresses the question of what it takes to obtain a well-de?ned extensive form game. Without relying on simplifying ?niteness or discreteness assumptions, we characterize the class of game trees for which (a) extensive forms can be de?ned and (b) all pure strategy combinations induce unique outcomes. The generality of the set-up covers “exotic” cases, like stochastic games or decision problems in continuous time (di?erential games). We ?nd that the latter class ful?lls the ?rst, but not the second requirement.

A System for Induction of Oblique Decision Trees

This article describes a new system for induction of oblique decision trees. This system, OC1, combines deterministic hill-climbing with two forms of randomization to find a good oblique split (in the form of a hyperplane) at each node of a decision tree. Oblique decision tree methods are tuned especially for domains in which the attributes are numeric, although they can be adapted to symbolic or mixed symbolic/numeric attributes. We present extensive empirical studies, using both real and artificial data, that analyze OC1's ability to construct oblique trees that are smaller and more accurate than their axis-parallel counterparts. We also examine the benefits of randomization for the construction of oblique decision trees.Comment: See http://www.jair.org/ for an online appendix and other files accompanying this articl

Terrestrial Ecology of the Dickey-Lincoln School Lakes Project

This introduction of the St. John River watershed is situated in a transitional zone between the Boreal Forest Formation and the Eastern Deciduous Forest Formation. Second-growth forests representative of these two ecosystems cover extensive areas of the project site. The boreal forest forms a broad transcontinental belt in northern North America and Eurasia, with southern montane extensions. This northern forest is characterized by evergreen, coniferous trees, predominately spruce-fir The eastern deciduous forest, composed of broad-leaved hardwoods, extends throughout the eastern United States except Florida (Dasmann, 1968; Oosting, 1956)

Mirror image hydrocarbons from Tropical and Boreal forests

Monoterpenes, emitted in large quantities by trees to attract pollinators and repel herbivores, can exist in mirror image forms called enantiomers. In this study such enantiomeric pairs have been measured in ambient air over extensive forest ecosystems in South America and northern Europe. For the dominant monoterpene, α-pinene, the (−)-form was measured in large excess over the (+)-form over the Tropical rainforest, whereas the reverse was observed over the Boreal forest. Interestingly, over the Tropical forest (−)-α-pinene did not correlate with its own enantiomer, but correlated well with isoprene. The results indicate a remarkable ecosystem scale enantiomeric fingerprint and a nexus between the biosphere and atmosphere

Ephedra alte (Joint Pine): An Invasive, Problematic Weedy Species in Forestry and Fruit Tree Orchards in Jordan

A field survey was carried out to record plant species climbed by Ephedra alte in certain parts of Jordan during 2008–2010. Forty species of shrubs, ornamental, fruit, and forest trees belonging to 24 plant families suffered from the climbing habit of E. alte. Growth of host plants was adversely affected by E. alte growth that extended over their vegetation. In addition to its possible competition for water and nutrients, the extensive growth it forms over host species prevents photosynthesis, smothers growth and makes plants die underneath the extensive cover. However, E. alte did not climb all plant species, indicating a host preference range. Damaged fruit trees included Amygdalus communis, Citrus aurantifolia, Ficus carica, Olea europaea, Opuntia ficus-indica, and Punica granatum. Forestry species that were adversely affected included Acacia cyanophylla, Ceratonia siliqua, Crataegus azarolus, Cupressus sempervirens, Pinus halepensis, Pistacia atlantica, Pistacia palaestina, Quercus coccifera, Quercus infectoria, Retama raetam, Rhamnus palaestina, Rhus tripartita, and Zizyphus spina-christi. Woody ornamentals attacked were Ailanthus altissima, Hedera helix, Jasminum fruticans, Jasminum grandiflorum, Nerium oleander, and Pyracantha coccinea. Results indicated that E. alte is a strong competitive for light and can completely smother plants supporting its growth. A. communis, F. carica, R. palaestina, and C. azarolus were most frequently attacked

Entomogenic Climate Change

Rapidly expanding insect populations, deforestation, and global climate change threaten to destabilize key planetary carbon pools, especially the Earth's forests which link the micro-ecology of insect infestation to climate. To the extent mean temperature increases, insect populations accelerate deforestation. This alters climate via the loss of active carbon sequestration by live trees and increased carbon release from decomposing dead trees. A positive feedback loop can emerge that is self-sustaining--no longer requiring independent climate-change drivers. Current research regimes and insect control strategies are insufficient at present to cope with the present regional scale of insect-caused deforestation, let alone its likely future global scale. Extensive field recordings demonstrate that bioacoustic communication plays a role in infestation dynamics and is likely to be a critical link in the feedback loop. These results open the way to novel detection and monitoring strategies and nontoxic control interventions.Comment: 7 pages, 1 figure; http://cse.ucdavis.edu/~chaos/chaos/pubs/ecc.ht

The silvopastoral landscape: patterns and functions of woody features of the territory crossed by flocks of sheep and goats

Multipurpose trees is a common type of agroforestry in several ecological regions ofthe world. In Trasos- Mantes region, Northeast of Portugal, they are a traditional component of Terra fria landscape and they could be seen in several forms: scatter trees, hedgerows, small wood lots, among others. Additionally, extensive livestock systems in this region are based on grazing itineraries across the landscape. In this practice flocks interacts with these structures using them for different purposes. Our purpose will be focused on woody features of landscape regarding species composition and shapes, their abundance and spacial distribution in order to examine how the grazing systems depends on the occurrence of these formations; particularly how animal species flocks composition are related on. By comparing the network of woody features in agriculture matrix with to grazing territory crossed by flocks, it is possible to recognize how the influence of grazing in the occurrence of these structures is. We believe that the role of these woody structures features in supporting of traditional silvopastoral systems has been sufficiently strong to change their distribution pattern. Single trees, hedgerows and wood lots structures associated with thirteen sheep flock journeys considering five different buffers -10, 20, 50, 100 and 200 meters- were recorded. Seasonality is very important to distinguish the sheep grazing itineraries. During autumn and spring, single trees and hedgerows are very demanded by shepherds and sheep. During summer and winter, these tree features seems not so important to decide the grazing journey. Single trees, hedgerows and wood lots are managed and configured to allow an optimum use of the landscape by sheep during the year. The animal behavior in each season determines the use of these structures

A Comparative Study of the Application of Different Learning Techniques to Natural Language Interfaces

In this paper we present first results from a comparative study. Its aim is to test the feasibility of different inductive learning techniques to perform the automatic acquisition of linguistic knowledge within a natural language database interface. In our interface architecture the machine learning module replaces an elaborate semantic analysis component. The learning module learns the correct mapping of a user's input to the corresponding database command based on a collection of past input data. We use an existing interface to a production planning and control system as evaluation and compare the results achieved by different instance-based and model-based learning algorithms.Comment: 10 pages, to appear CoNLL9