| 1. |
- Bol, Roland, et al.
(författare)
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Tabulated resolution for the well-founded semantics
- 1998
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Ingår i: The journal of logic programming. - 0743-1066 .- 1873-5789. ; 34:2, s. 67-109
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Tidskriftsartikel (refereegranskat)abstract
- Based on the search forest for positive programs as defined by Bol and Degerstedt, we define a tabulation-based framework that is sound and complete (when floundering does not occur) w.r.t. the well-founded semantics. In contrast to SLS-resolution as proposed by Przymusinski and by Ross, a positivistic computation rule is not required. Moreover, unlike SLG-resolution due to Chen and Warren, our proposal relies on tabulation for both positive and negative recursion without losing the clear separation of the search space from search strategies. In particular, the newly proposed search forest is finite for nonfloundering functor-free programs.
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| 3. |
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| 4. |
- Kruse, Jens, et al.
(författare)
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Innovative methods in soil phosphorus research: A review
- 2015
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Ingår i: Journal of Plant Nutrition And Soil Science/Zeitschrift für Pflanzenernahrung und Bodenkunde. - : Wiley-VCH Verlagsgesellschaft. - 1436-8730 .- 1522-2624. ; 178:1, s. 43-88
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Tidskriftsartikel (refereegranskat)abstract
- Phosphorus (P) is an indispensable element for all life on Earth and, during the past decade,concerns about the future of its global supply have stimulated much research on soil P and meth-od development. This review provides an overview of advanced state-of-the-art methods cur-rently used in soil P research. These involve bulk and spatially resolved spectroscopic and spec-trometric P speciation methods (1 and 2D NMR, IR, Raman, Q-TOF MS/MS, high resolution-MS,NanoSIMS, XRF, XPS, (m)XAS) as well as methods for assessing soil P reactions (sorption iso-therms, quantum-chemical modeling, microbial biomass P, enzymes activity, DGT,33P isotopicexchange,18O isotope ratios). Required experimental set-ups and the potentials and limitationsof individual methods present a guide for the selection of most suitable methods or combina-tions
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| 5. |
- Mildner, Per, 1963-
(författare)
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Type Domains for Abstract Interpretation : A critical study
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Programming languages with dynamic typing such as Prolog do not require that the programmer declares the types of data or procedures. This flexibility, however, comes at a price. The lack of declarations makes it hard for a compiler to produce fast code since data must be assumed to be of any type.Abstract interpretation is a technique to automatically infer conservative approximations of program properties such as the types of program variables and procedure arguments. The properties of interest are described using an abstract domain. The abstract domains for type analysis investigated in this thesis are based on deterministic term grammars but differ in the representation of the term grammars and in the widening used, that is, the method used to ensure that the analysis terminates.One proposed representation of term grammars, type graphs, are shown to be exponentially larger than the term grammars they represent not only in the worst case but also in practice. One previously proposed widening for type graphs is shown to be impractically expensive and also no more precise than other more efficient methods. A novel implementation technique is proposed for another type graph widening that appears in the literature. The precision using this implementation technique is shown to be better than for the other investigated widenings. The performance, however, suffers from the problems inherent in the type graph representation unless some crucial modifications to the analyzer are made.To overcome the problems with the type graph representation a more compact representation of term grammars is proposed. A number of widenings using this representation are investigated and shown not to suffer from problems with huge term grammar representations. The precision obtained using these widenings are as good or better than the precision obtained using the original widening proposed for type graphs.Finally, two sets of benchmarks that have been used in the literature to investigate analysis methods are considered. It is shown that these benchmarks will give unrealistically good absolute precision and one set of benchmarks, the GAIA benchmarks, is shown to have further deficiencies that make it completely unsuitable for benchmarking purposes.
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| 6. |
- van Soest, Maud A. J., et al.
(författare)
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Grazing and topography control nutrient pools in low Arctic soils of Southwest Greenland
- 2022
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Ingår i: European Journal of Soil Science. - : John Wiley & Sons. - 1351-0754 .- 1365-2389. ; 73:4
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Tidskriftsartikel (refereegranskat)abstract
- Soil nutrient pools in the dry low Arctic are likely to be released under climatic change and this bioavailability has the potential to increase both terrestrial and aquatic productions. As well as the direct effect of warming, external disturbances such as nutrient deposition and grazing can also drive ecosystem change. This study in the low Arctic Kangerlussuaq area of southwest Greenland compared soil nutrient pools in terms of both topographic position on a catena and by soil depth in two small catchments with contrasting muskox abundance. We tested the hypotheses that there were differences between soil carbon (C), nitrogen (N) and phosphorus (P) across a soil catena (ridge - slope - valley) and by soil depth (litter - 0–5 cm - 25–30 cm) for the two sites (SS17b, muskox present, versus - SS85, no muskox). Total C and N concentrations of soils were on average lower at SS17b compared to SS85. Moreover, the soil N concentration increased downslope in the catena with higher amounts in the valleys compared to the slopes and ridges. Soil P concentration (0.70 g P kg−1) was similar between catchments; however, litter P content was substantially different. The difference in soil nutrients between the two catchments was most likely due to the presence of muskox at SS17b, and hence grazing associated processes (defecation, altered microbiology and nutrient cycling). This study emphasises the heterogeneity of arctic landscapes and need for ecosystem specific research.Highlights:Soil nutrient pools in two low-arctic catchments in Greenland were compared.Grazing and dung inputs by muskox affect soil nutrient pools in Greenland.Soil P stores in Kangerlussuaq are similar to intensively managed farmland in Europe.The heterogeneity of arctic landscapes and need for ecosystem-specific research are emphasised.
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