763 research outputs found

    Applications of Intuitionistic Logic in Answer Set Programming

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    We present some applications of intermediate logics in the field of Answer Set Programming (ASP). A brief, but comprehensive introduction to the answer set semantics, intuitionistic and other intermediate logics is given. Some equivalence notions and their applications are discussed. Some results on intermediate logics are shown, and applied later to prove properties of answer sets. A characterization of answer sets for logic programs with nested expressions is provided in terms of intuitionistic provability, generalizing a recent result given by Pearce. It is known that the answer set semantics for logic programs with nested expressions may select non-minimal models. Minimal models can be very important in some applications, therefore we studied them; in particular we obtain a characterization, in terms of intuitionistic logic, of answer sets which are also minimal models. We show that the logic G3 characterizes the notion of strong equivalence between programs under the semantic induced by these models. Finally we discuss possible applications and consequences of our results. They clearly state interesting links between ASP and intermediate logics, which might bring research in these two areas together.Comment: 30 pages, Under consideration for publication in Theory and Practice of Logic Programmin

    The Economics of Fishing: Intertemporal Equilibria in a Two-Country Transboundary Resource

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    Treballs Finals del Màster d'Economia, Facultat d'Economia i Empresa, Universitat de Barcelona, Curs: 2016-2017, Tutors: Jesús Marín-Solano & Jorge Navas RódenesFor the problem of two-country fisheries sharing a common resource we calculate the precommitment solutions and address the time consistent ones. We analyse different initial states in order to obtain the optimal paths to reach a steady state. The two-agent problem is determine by the efficiency of each country and their discount rate, different levels of efficiency and discounting are set in order to find their relative consequences between both players. We find that the optimal path is depending on the other country behaviour, and that in the long run the final state may be different than the initial. The results of the model implementation may be extended to other type of renewable resources. This study is providing new insights in the two Player equilibria for the case of two agents transboundary fishing resource that may be used by policymakers facing fisheries management

    Estimativos de error para un método de Galerkin libre de mallas en múltiples dimensiones con derivadas difusas y estabilización

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    A meshfree method with diffuse derivatives and a penalty stabilization is developed. An error analysis for the approximation of the solution of a general elliptic differential equation, in several dimensions, with Neumann boundary conditions is provided. Theoretical and numerical results show that the approximation error and the convergence rate are better than the diffuse element method.Se desarrolla un método sin malla con derivados de uso difuso y una estabilización de penalización. Se proporciona un análisis de error para la aproximación de la solución de una ecuación diferencial elíptica general, en varias dimensiones, con condiciones de contorno de Neumann. Los resultados teóricos y numéricos muestran que el error de aproximación y la tasa de convergencia son mejores que el método del elemento de uso

    4,4'-Dimethyl-2,2'-{[2,3,3a,4,5,6,7,7a-octa-hydro-1H-benzimidazole-1,3-di-yl]bis-(methyl-ene)}diphenol

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    The asymmetric unit of the title compound, C23H30N2O2, contains one half-mol-ecule, with a twofold axis splitting the mol-ecule in two identical halves. The structure of the racemic mixture has been reported previously [Rivera et al. (2009>) J. Chem. Crystallogr. 39, 827-830] but the enanti-omer reported here crystallized in the ortho-rhom-bic space group P21212 (Z = 2), whereas the racemate occurs in the triclinic space group P-1 (Z = 2). The observed mol-ecular conformation is stabilized by two intra-molecular O-H⋯N hydrogen bonds, which generate rings with graph-set motif S(6). In the crystal, mol-ecules are linked via non-classical C-H⋯O inter-actions, which stack the mol-ecules along the b axis

    Theory of partial-order programming

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    This paper shows the use of partial-order program clauses and lattice domains for declarative programming. This paradigm is particularly useful for expressing concise solutions to problems from graph theory, program analysis, and database querying. These applications are characterized by a need to solve circular constraints and perform aggregate operations, a capability that is very clearly and efficiently provided by partial-order clauses. We present a novel approach to their declarative and operational semantics, as well as the correctness of the operational semantics. The declarative semantics is model-theoretic in nature, but the least model for any function is not the classical intersection of all models, but the greatest lower bound/least upper bound of the respective terms defined for this function in the different models. The operational semantics combines top-down goal reduction with memo-tables. In the partial-order programming framework, however, memoization is primarily needed in order to detect circular circular function calls. In general we need more than simple memoization when functions are defined circularly in terms of one another through monotonic functions. In such cases, we accumulate a set of functional-constraint and solve them by general fixed-point-finding procedure. In order to prove the correctness of memoization, a straightforward induction on the length of the derivation will not suffice because of the presence of the memo-table. However, since the entries in the table grow monotonically, we identify a suitable table invariant that captures the correctness of the derivation. The partial-order programming paradigm has been implemented and all examples shown in this paper have been tested using this implementation

    Estandarización y aplicación de un método espectrofluorométrico para la identificación de inhibidores de la Proteasa Aspartica Secretada (SAP) de cándida ALBICANS, a partir de extractos de plantas de la familia melastomataceae y rubiaceae

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    En el presente trabajo se realizó la estandarización de un método espectrofluorométrico para la medición de Sap de C. albicans, para lo cual se utilizo un espectrofotómetro de fluorescencia. Se determinaron las condiciones óptimas de funcionamiento del equipo y se hallaron las concentraciones ideales para los reactivos utilizados, también se estableció las condiciones del cultivo para la obtención de Sap. Con el fin de encontrar inhibidores de esta proteasa, se evaluaron extractos acuosos, butanólicos y en acetato de etilo de las plantas Polycurea lirystipula (Rubiácea), Miconia coronata y Clidemia hirta (Melastomatácea). Además de esta técnica, se utilizaron otras metodologías para corroborar la actividad de Sap y su inhibición, como fue la cromatografía liquida de alta eficiencia (HPLC), electroforesis SDS-PAGE e hidrólisis en medio de hemoglobina, mediante las cuales se monitoreó la producción de Sap durante un periodo de incubación de 26 horas, donde se observó el tiempo en que se inicia la secreción de Sap y se identificó el periodo de mayor producción. Se realizaron ensayos para verificar la acción inhibitoria de pepstatin A y se evaluaron los extractos aplicando las metodologías antes mencionadas, obteniendo como resultado inhibición de Sap por parte de los extractos acuosos de Polycurea lirystipula y Miconia coronata, y butanólicos de Polycurea lirystipula y Clidemia hirta, donde Polycurea lirystipula presentó los porcentajes más altos de inhibición
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