Search

Holographic algorithms introduced by Valiant have two ingredients: matchgates, which are gadgets realizing local constraint functions by weighted planar perfect matchings, and holographic reductions, which show equivalences among problems with different descriptions via basis transformations. In this paper, we replace matchgates in the paradigm above by the affine type and the product type constraint functions, which are known to be tractable in general (not necessarily planar) graphs. We present polynomial-time algorithms to decide if a given counting problem has a holographic reduction to another problem defined by the affine or product-type functions. We also give polynomial-time algorithms to the same problems for symmetric functions, where the complexity is measured in terms of the (exponentially more) succinct representations. The latter result implies that the symmetric Boolean Holant dichotomy (Cai, Guo, and Williams, SICOMP 2016) is efficiently decidable. Our proof techniques are mainly algebraic. [ABSTRACT FROM AUTHOR]

Abstract: This paper is concerned with the spreading speeds and traveling wave solutions of a nonlocal dispersal equation with degenerate monostable nonlinearity. We first prove that the traveling wave solution with critical minimal speed decays exponentially as , while other traveling wave solutions with do not decay exponentially as . Then the monotonicity and uniqueness (up to translation) of traveling wave solution with critical minimal speed is established. Finally, we prove that the critical minimal wave speed coincides with the asymptotic speed of spread. [Copyright &y& Elsevier]

Abstract: This paper studies the existence, uniqueness and asymptotic behavior of the solution for a half-space linearized stationary Boltzmann equation with an external force term, in the case of a specified incoming distribution at the boundary and a given mass flux. Without the external force, the solution of the stationary Boltzmann equation has been proved to tend toward a constant state, which is independent of the space variable. Due to the presence of the external force, we show that the solution tends to some function which depends on the space variable. [Copyright &y& Elsevier]

Abstract: In this paper we consider a hybrid elastic model consisting of a Timoshenko beam and a tip load at the free end of the beam. We show that uniform stabilization of the model which includes the rotary inertia of the tip load can be obtained when feedback boundary moment and force controls are applied at the point of contact between the beam and the tip load. However, in the presence of the load stabilization is “slower” and subject to a restriction on the boundary data at the free end of the beam. [Copyright &y& Elsevier]

The EU Water Framework Directive (WFD) requires member states to take measures to ensure that bodies of water will be in good chemical and ecological condition by 2015. Important measures to achieve this goal include reducing emissions of nitrogen (N) and phosphate (P2O5) from manure and mineral fertilizers into the environment. In regions with a high livestock density, this measure is expected to affect agricultural production and income. To quantify these effects, an environmental economic model is required that can assess alternatives capable of reducing N and P2O5 potential emissions to water. In this paper, we develop a model that is capable of analysing changes in potential emissions to water of N and P2O5 and apply it to the Netherlands, a country with large nutrient emissions. Compared to a 2015 reference scenario based on current efforts to reduce nutrient emissions, we found that the WFD measures will increase regional transport and export of manure and reduce the number of animals in the Netherlands. Fodder adjustments (defined as lower N and P2O5 input in purchased fodder) to decrease nutrient excretion in manure were a less attractive option than amongst others export, transportation of manure to another region, land use changes or reduction of the number of livestock. Compared to the reference scenario in 2015, total agricultural income will decrease by about €81.5 million per year (about €49/ha per year), although the effects will differ among parts of the Netherlands and agricultural sectors. The average predicted decrease in N emissions from agricultural sites, vulnerable to leaching into bodies of water will be almost 20% or approximately 14.7kgN/ha per year. The reduction in N emissions to air from animal sheds, manure storage systems, application of animal manure and mineral fertilisers to the crops and grazing animals equals 6.5% or 5kg ammonia (NH3) per hectare. [Copyright &y& Elsevier]

Abstract: In this paper a new class of higher order -type I functions for a multiobjective programming problem is introduced, which subsumes several known studied classes. Higher order Mond–Weir and Schaible type dual programs are formulated for a nondifferentiable multiobjective fractional programming problem where the objective functions and the constraints contain support functions of compact convex sets in . Weak and strong duality results are studied in both the cases assuming the involved functions to be higher order -type I. A number of previously studied problems appear as special cases. [Copyright &y& Elsevier]

The Piedmont Region in NW Italy has recently deployed an ambitious and pioneering agricultural water pricing reform aimed at integrating and effectively enforcing EU's Water Framework Directive principles of cost recovery, polluter-pays and affordability. This paper develops a multi-model ensemble framework encompassing 5 mathematical programming models (2 Positive Mathematical Programming models, 2 Positive Multi-Attribute Utility Programming models and 1 Weighted Goal Programming model) that represent the observed behavior of socioeconomic agents to: 1) simulate the impacts of the Piedmontese water pricing reform on land use allocation and management, water conservation, profit and water tariff revenue; 2) sample modeling uncertainty through the ensemble spread; and 3) explore potential tipping points through use of scenario-discovery techniques. Our research suggests that the key challenge to the reform lies in the management of rice fields, an extensive (17% of the agricultural area), water-demanding and relatively low-added-value crop that nonetheless delivers significant ecosystem services (e.g. water retention) of historical and cultural relevance to the region. The ensemble experiment suggests that rice agriculture rapidly dwindles in the price range 0.012–0.074 EUR/m3 depending on the model. Before reaching this tipping point, agricultural water pricing can reduce withdrawals up to 1.7%–9.5%, while reducing profit between 4.9% and 5.6% and achieving a 57- to 65-fold increase in water tariff revenue. • We combine a multi-model ensemble experiment with scenario discovery techniques. • Our approach samples modeling and scenario uncertainty to identify tipping points. • Our approach is illustrated using the agricultural water pricing in Piedmont (IT). • Results show historical rice fields dwindle in the price range 0.014–0.074 EUR/m3. • Conserving rice fields considerably limits pricing water conservation potential. [ABSTRACT FROM AUTHOR]