167,718 research outputs found

    Solving General Arithmetic Word Problems

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    This paper presents a novel approach to automatically solving arithmetic word problems. This is the first algorithmic approach that can handle arithmetic problems with multiple steps and operations, without depending on additional annotations or predefined templates. We develop a theory for expression trees that can be used to represent and evaluate the target arithmetic expressions; we use it to uniquely decompose the target arithmetic problem to multiple classification problems; we then compose an expression tree, combining these with world knowledge through a constrained inference framework. Our classifiers gain from the use of {\em quantity schemas} that supports better extraction of features. Experimental results show that our method outperforms existing systems, achieving state of the art performance on benchmark datasets of arithmetic word problems.Comment: EMNLP 201

    Phloem cytochemical modification and gene expression following the recovery of apple plants from apple proliferation

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    Recovery of apple trees from apple proliferation was studied by combining ultrastructural, cytochemical, and gene expression analyses to possibly reveal changes linked to recovery-associated resistance. When compared with either healthy or visibly diseased plants, recovered apple trees showed abnormal callose and phloem-protein accumulation in their leaf phloem. Although cytochemical localization detected Ca2+ ions in the phloem of all the three plant groups, Ca2+ concentration was remarkably higher in the phloem cytosol of recovered trees. The expression patterns of five genes encoding callose synthase and of four genes encoding phloem proteins were analyzed by quantitative real-time reverse transcription- polymerase chain reaction. In comparison to both healthy and diseased plants, four of the above nine genes were remarkably upregulated in recovered trees. As in infected apple trees, phytoplasma disappear from the crown during winter, but persist in the roots, and it is suggested that callose synthesis/deposition and phloem-protein plugging of the sieve tubes would form physical barriers preventing the recolonization of the crown during the following spring. Since callose deposition and phloem-protein aggregation are both Ca2+-dependent processes, the present results suggest that an inward flux of Ca2+ across the phloem plasma membrane could act as a signal for activating defense reactions leading to recovery in phytoplasma-infected apple trees.L'articolo Ă© disponibile sul sito dell'editore: http://www.apsjournals.apsnet.or

    A Comparison of Well-Quasi Orders on Trees

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    Well-quasi orders such as homeomorphic embedding are commonly used to ensure termination of program analysis and program transformation, in particular supercompilation. We compare eight well-quasi orders on how discriminative they are and their computational complexity. The studied well-quasi orders comprise two very simple examples, two examples from literature on supercompilation and four new proposed by the author. We also discuss combining several well-quasi orders to get well-quasi orders of higher discriminative power. This adds 19 more well-quasi orders to the list.Comment: In Proceedings Festschrift for Dave Schmidt, arXiv:1309.455

    Lie algebra configuration pairing

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    We give an algebraic construction of the topological graph-tree configuration pairing of Sinha and Walter beginning with the classical presentation of Lie coalgebras via coefficients of words in the associative Lie polynomial. Our work moves from associative algebras to preLie algebras to graph complexes, justifying the use of graph generators for Lie coalgebras by iteratively expanding the set of generators until the set of relations collapses to two simple local expressions. Our focus is on new computational methods allowed by this framework and the efficiency of the graph presentation in proofs and calculus involving free Lie algebras and coalgebras. This outlines a new way of understanding and calculating with Lie algebras arising from the graph presentation of Lie coalgebras.Comment: 21 pages; uses xypic; ver 4. added subsection 3.4 outlining another computational algorithm arising from configuration pairing with graph

    Individual and Domain Adaptation in Sentence Planning for Dialogue

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    One of the biggest challenges in the development and deployment of spoken dialogue systems is the design of the spoken language generation module. This challenge arises from the need for the generator to adapt to many features of the dialogue domain, user population, and dialogue context. A promising approach is trainable generation, which uses general-purpose linguistic knowledge that is automatically adapted to the features of interest, such as the application domain, individual user, or user group. In this paper we present and evaluate a trainable sentence planner for providing restaurant information in the MATCH dialogue system. We show that trainable sentence planning can produce complex information presentations whose quality is comparable to the output of a template-based generator tuned to this domain. We also show that our method easily supports adapting the sentence planner to individuals, and that the individualized sentence planners generally perform better than models trained and tested on a population of individuals. Previous work has documented and utilized individual preferences for content selection, but to our knowledge, these results provide the first demonstration of individual preferences for sentence planning operations, affecting the content order, discourse structure and sentence structure of system responses. Finally, we evaluate the contribution of different feature sets, and show that, in our application, n-gram features often do as well as features based on higher-level linguistic representations

    Generating trees for permutations avoiding generalized patterns

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    We construct generating trees with one, two, and three labels for some classes of permutations avoiding generalized patterns of length 3 and 4. These trees are built by adding at each level an entry to the right end of the permutation, which allows us to incorporate the adjacency condition about some entries in an occurrence of a generalized pattern. We use these trees to find functional equations for the generating functions enumerating these classes of permutations with respect to different parameters. In several cases we solve them using the kernel method and some ideas of Bousquet-M\'elou. We obtain refinements of known enumerative results and find new ones.Comment: 17 pages, to appear in Ann. Com

    Mayer expansion of the Nekrasov pre potential: the subleading ϵ2\epsilon_2-order

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    The Mayer cluster expansion technique is applied to the Nekrasov instanton partition function of N=2\mathcal{N}=2 SU(Nc)SU(N_c) super Yang-Mills. The subleading small ϵ2\epsilon_2-correction to the Nekrasov-Shatashvili limiting value of the prepotential is determined by a detailed analysis of all the one-loop diagrams. Indeed, several types of contributions can be distinguished according to their origin: long range interaction or potential expansion, clusters self-energy, internal structure, one-loop cyclic diagrams, etc.. The field theory result derived more efficiently in [1], under some minor technical assumptions, receives here definite confirmation thanks to several remarkable cancellations: in this way, we may infer the validity of these assumptions for further computations in the field theoretical approach.Comment: 29 pages, 9 figure
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