Induction of First-Order Decision Lists: Results on Learning the Past Tense of English Verbs

This paper presents a method for inducing logic programs from examples that learns a new class of concepts called first-order decision lists, defined as ordered lists of clauses each ending in a cut. The method, called FOIDL, is based on FOIL (Quinlan, 1990) but employs intensional background knowledge and avoids the need for explicit negative examples. It is particularly useful for problems that involve rules with specific exceptions, such as learning the past-tense of English verbs, a task widely studied in the context of the symbolic/connectionist debate. FOIDL is able to learn concise, accurate programs for this problem from significantly fewer examples than previous methods (both connectionist and symbolic).Comment: See http://www.jair.org/ for any accompanying file

A COST-EFFECTIVENESS ANALYSIS OF ACTIONS TO REDUCE STREAM TEMPERATURE AT THE WATERSHED SCALE

A cost-effectiveness frontier is developed to compare economic and environmental tradeoffs associated with planting a riparian buffer to reduce stream temperature at the watershed scale. Results indicate that total welfare change and its distribution among sectors vary between scenarios. The policy selected may differ if riparian plantings are voluntary rather than mandatory.Environmental Economics and Policy, Land Economics/Use,

OPTIMAL SPATIAL SCALE FOR EVALUATING ECONOMIC AND ENVIRONMENTAL TRADEOFFS

This paper develops a conceptual framework that can provide a scientific foundation for formulating policies that consider environmental and economic tradeoffs. It addresses a critical problem recognized in the environmental sciences, namely, choosing the appropriate spatial scale for measurement and analysis of spatially variable economic and biophysical processes.scale, carbon sequestration, agriculture, economic policy, Environmental Economics and Policy, Industrial Organization,

A study of the energy content of the seismic waves P and pP

The energy observed in the seismic waves P and pP in a large number of earthquakes is compared, by means of two partly independent methods, with the theoretical energy calculated from a standard equation. The results are analyzed, depth of focus, distance from epicenter to observing station, geographical location of epicenter, and azimuth from station being used as variables. When compared with the theoretical ratio, the ratio of the energy in pP to the energy in P averaged over a distance range 60°-90° is observed to decrease with depth, by 0.5 on a logarithmic scale of energy between 100 and 600 km. depth of focus. The results for the two waves are compared separately with theoretical values, and the observed effect appears to be about equally due to an increase of P energy and a decrease of pP energy with depth. The theoretical formula is reëxamined to determine if permissible changes in the assumptions or numerical values can account for the results. No such changes are found; certain assumptions with respect to increased absorption of energy near the surface of the earth provide a partial qualitative explanation, but quantitatively they cannot be reconciled with data from other sources. The variation with distance between observed and calculated energies is not large enough to be treated quantitatively; slight changes in the slope of the accepted velocity vs. depth curve are tentatively suggested on the basis of it. The energy ratio pP/P compared to the theoretical ratio is significantly too large in shallow earthquakes occurring in the Aleutian region and can be attributed to pP rather than P. For shallow shocks in the New Hebrides region and very deep shocks of the Southwest Pacific there is some indication that the energy ratio is smaller than for comparable shocks elsewhere. Data on observed wave periods are given. The effect of differences between instruments is considered

Alien Registration- Mooney, James M. (Houlton, Aroostook County)

https://digitalmaine.com/alien_docs/34810/thumbnail.jp

CONTRACTING FOR SOIL CARBON CREDITS: DESIGN AND COSTS OF MEASUREMENT AND MONITORING

Many firms anticipate that a cap on greenhouse gas emissions will eventually be imposed, either through an international agreement like the Kyoto protocol or through domestic policy, and have started to take voluntary actions to reduce their emissions. If agricultural producers participate in the emerging market for tradable C-credits, it must be possible to verify that actions farmers take do increase the amount of C in soils and this increase can be maintained over the length of the contract. In this paper we develop a prototype measurement and monitoring scheme for C-credits sequestered in agricultural soils and estimate its costs for the small grain-producing region of Montana using an econometric-process simulation model. Three key results emerge from the prototype framework. First, the efficiency of measurement and monitoring procedures for agricultural soil C sequestration depends on the price of C credits. Second, we find that at all price levels, costs of measuring and monitoring are largest in areas that exhibit the greatest heterogeneity in carbon values. Third, in a case study application of our prototype measurement and monitoring scheme, we find that if we assume similar error and confidence levels as forestry contracts, the upper estimate of measurement and monitoring costs associated with a contract that pays farmers per tonne of C sequestered is 3% of the value of a C-credit. This cost is small relative to the estimated net value of the contract. Thus we conclude that measurement and monitoring costs are not likely to be large enough to prevent producers from participating in a market for tradable credits.Environmental Economics and Policy,