Weak and strong disjunction in possibilistic asp

Abstract. Possibilistic answer set programming (PASP) unites answer set programming (ASP) and possibilistic logic (PL) by associating certainty values with rules. The resulting framework allows to combine both non-monotonic reasoning and reasoning under uncertainty in a single framework. While PASP has been well-studied for possibilistic definite and possibilistic normal programs, we argue that the current semantics of possibilistic disjunctive programs are not entirely satisfactory. The problem is twofold. First, the treatment of negation-as-failure in existing approaches follows an all-or-nothing scheme that is hard to match with the graded notion of proof underlying PASP. Second, we advocate that the notion of disjunction can be interpreted in several ways. In particular, in addition to the view of ordinary ASP where disjunctions are used to induce a non-deterministic choice, the possibilistic setting naturally leads to a more epistemic view of disjunction. In this paper, we propose a semantics for possibilistic disjunctive programs, discussing both views on disjunction. Extending our earlier work, we interpret such programs as sets of constraints on possibility distributions, whose least specific solutions correspond to answer sets.

A systematic review of evidence to inform HIV prevention interventions among men who have sex with men in Europe.

An estimated 42% of all newly diagnosed HIV cases in Europe in 2013 were transmitted during sex between men. This review was performed to identify and describe studies evaluating the efficacy and effectiveness of HIV prevention interventions among men who have sex with men (MSM), in relation to implementation data from European settings. A systematic search was performed individually for 24 interventions.Data were extracted from studies including efficacy or implementation data from European settings,appraised for efficacy, implementation and plausibility, and assigned a grade (1-4) according to the Highest Attainable Standard of Evidence (HASTE)framework. Four interventions (condom use, peer outreach,peer-led groups, and using universal coverage of antiretroviral treatment and treatment as prevention)were assigned the highest HASTE grade, 1. Another four interventions were assigned 2a for probable recommendation, including voluntary counseling and testing for HIV, using condom-compatible lubricant,using post-exposure prophylaxis, and individual counselling for MSM living with HIV. In addition, seven interventions were assigned a grade of 2b, for possible recommendation. Encouragingly, 15 interventions were graded to be strongly, probably or possibly recommended.In the relatively resource-rich European setting, there is an opportunity to provide global leadership with regard to the regional scale-up of comprehensive HIV prevention interventions for MSM

Giant spontaneous magnetostriction in MnTe driven by a novel magnetostructural coupling mechanism

We present a comprehensive x-ray scattering study of spontaneous magnetostriction in hexagonal MnTe, an antiferromagnetic semiconductor with a Neel temperature of $T_{\mathrm{N}} = 307$ K. We observe the largest spontaneous magnetovolume effect known for an antiferromagnet, reaching a volume contraction of $|\Delta V/V| > 7 \times 10^{-3}$. This can be justified semiquantitatively by considering bulk material properties, the spatial dependence of the superexchange interaction, and the geometrical arrangement of magnetic moments in MnTe. The highly unusual linear scaling of the magnetovolume effect with the short-range magnetic correlations, beginning in the paramagnetic state well above $T_{\mathrm{N}}$, points to a novel physical mechanism, which we explain in terms of a trilinear coupling of the elastic strain with superposed distinct domains of the antiferromagnetic order parameter. This novel mechanism for coupling lattice strain to robust short-range magnetic order casts new light on magnetostrictive phenomena and also provides a template by which the exceptional magnetostrictive properties of MnTe might be realized in a wide range of other functional materials.Comment: Submitted May 11, 202

Modeling Stable Matching Problems with Answer Set Programming

The Stable Marriage Problem (SMP) is a well-known matching problem first introduced and solved by Gale and Shapley (1962). Several variants and extensions to this problem have since been investigated to cover a wider set of applications. Each time a new variant is considered, however, a new algorithm needs to be developed and implemented. As an alternative, in this paper we propose an encoding of the SMP using Answer Set Programming (ASP). Our encoding can easily be extended and adapted to the needs of specific applications. As an illustration we show how stable matchings can be found when individuals may designate unacceptable partners and ties between preferences are allowed. Subsequently, we show how our ASP based encoding naturally allows us to select specific stable matchings which are optimal according to a given criterion. Each time, we can rely on generic and efficient off-the-shelf answer set solvers to find (optimal) stable matchings.Comment: 26 page

Hydration and air entrainment challenges of high-volume fly ash concrete pavement

The goal of high-volume fly ash concrete (HVFAC) is to produce concrete pavements at a lower cost and carbon footprint while maintaining its desired durability. Previous research has demonstrated that the required fresh and hardened concrete properties can be achieved at higher replacement rates of cement with fly ash such as 40%. However, most transportation agencies do not permit more than 30% cement replacement with fly ash primarily because of the potential inconsistencies in early-age properties such as variable air entrainment, delays in setting times, and lower strength gains. In this paper, the heat evolved during hydration of HVFAC are presented with respect to the source of the cement and fly ash, the variability of fly ash from the same source, and addition of nano limestone. Isothermal calorimetry showed longer setting times were dependent on the specific fly ash-cement combination as well as the degree of sulfate imbalance. For this study, HVFAC mixes with class C fly ash had a larger sulfate imbalance than class F fly ash with final setting times 4.5 hours and 1.9 hours longer than straight cement system, respectively. Replacing cement with 10% nano limestone in HVFAC system accelerated the initial set time by 3.2 hours which was much greater than the set time acceleration (1.3 hours) with the replacement of straight cement with 10% nano limestone. The various types of inorganic and organic carbons in fly ash remain a challenge for predicting and maintaining air content but the foam index still offers a rapid and straightforward quality control test with operator variability within ±1 µL AEA/gm fly ash

Dinuclear copper (II) and nickel (II) systems with planar M₂N₂O₂ bridge

The tridentate ligand systemb (abbreviated as inkR2) readily yield copper (II) and nickel (II) species of the formula M2 (inkR2)2(CLO4)2. 2xH2O (x=0–1). Dinuclear formulation is based on variable temperature magnetic susceptibility and conductivity data and on the known structure of some related systems. The Cu2 (inkR2)22+ species are strongly antiferromagnetic (−2J=600–800 cm−1) while the Ni2(inkR2)22+ species are diamagnetic. The major coordination sphere is planar around each metal (II). The metal ions in a dimer are linked by planar M2N2O2 bridge. The copper (II) and nickel (II) species freely form solid solutions. In these statistical scrambling of copper and nickel occur among the metal ion sites of the dimeric structure. Powder epr spectra of such mixed crystals are indicative of axial geometry around copper (II) ion

A feminist vision for transformative change to disaster risk reduction policies and practices

Gender has received increased attention in disaster risk reduction (DRR) policies and practices over the past three decades. However, a critical analysis raises a number of questions: has the attention to gender brought transformative change to the lives of people, especially women and sexual minorities in all their diversity? To what extent has the inclusion of a gender perspective in DRR challenged the root causes of vulnerability and marginalization? Do the current gender sensitive DRR policies and practices have transformative potential? In this paper, we explore some of these questions with particular reference to the recent Disaster Risk Reduction and Management (DRRM) Act 2017 and current DRR practices in Nepal in which gender has been included. We present findings from three research projects, undertaken between 2016 and 2019 in six locations in Nepal. These comprised 105 individual interviews, 11 group interviews and 3 focus group discussions (FGDs) with internally displaced women; pregnant and newly delivered women; health and community workers; policy makers, political leaders and organisations working on DRR. We argue that, despite increased attention to gender, current DRR policies and practices do little to challenge existing, unequal social and institutional structures; instead, they accommodate the gender status quo. We suggest that in order for transformative social change to occur, we require a transformative vision; one that allows us to see the biases and problems within the current DRR policies and practices and allows us to imagine our future differently. A feminist vision offers that possibility