The representation of a temporal problem in answer set programming (ASP) usually boils down to using copies of variables and constraints, one for each time stamp, no matter whether it is directly encoded or expressed via an action or temporal language. The multiplication of variables and constraints is commonly done during grounding, and the solver is completely ignorant about the temporal relationship among the different instances. On the other hand, a key factor in the performance of today’s ASP solvers is conflict-driven constraint learning. Our question in this paper is whether a constraint learned for particular time steps can be generalized and reused at other time steps, and ultimately whether this enhances the overall solver performance on temporal problems. Knowing well the domain of time, we study conditions under which learned dynamic constraints can be generalized. Notably, we identify a property of temporal representations that enables the generalization of learned constraints across all time steps. It turns out that most ASP planning encodings either satisfy this property or can be easily adapted to do so. In addition, we propose a general translation that transforms programs to fulfill this property. Finally, we empirically evaluate the impact of adding the generalized constraints to an ASP solver.

We are interested in automating reasoning with and about study regulations, catering to various stakeholders, ranging from administrators, over faculty, to students at different stages. Our work builds on an extensive analysis of various study programs at the University of Potsdam. The conceptualization of the underlying principles provides us with a formal account of study regulations. In particular, the formalization reveals the properties of admissible study plans. With these at end, we propose an encoding of study regulations in Answer Set Programming that produces corresponding study plans. Finally, we show how this approach can be extended to a generic user interface for exploring study plans.

We present plingo, an extension of the answer set programming (ASP) system clingo that incorporates various probabilistic reasoning modes. Plingo is based on $\textit{Lpmln}^{\pm }$, a simple variant of the probabilistic language Lpmln, which follows a weighted scheme derived from Markov logic. This choice is motivated by the fact that the main probabilistic reasoning modes can be mapped onto enumeration and optimization problems and that $\textit{Lpmln}^{\pm }$ may serve as a middle-ground formalism connecting to other probabilistic approaches. Plingo offers three alternative frontends, for Lpmln, P-log, and ProbLog. These input languages and reasoning modes are implemented by means of clingo’s multi-shot and theory-solving capabilities. In this way, the core of plingo is an implementation of $\textit{Lpmln}^{\pm }$ in terms of modern ASP technology. On top of that, plingo implements a new approximation technique based on a recent method for answer set enumeration in the order of optimality. Additionally, in this work, we introduce a novel translation from $\textit{Lpmln}^{\pm }$ to ProbLog. This leads to a new solving method in plingo where the input program is translated and a ProbLog solver is executed. Our empirical evaluation shows that the different solving approaches of plingo are complementary and that plingo performs similarly to other probabilistic reasoning systems.

Seabirds are highly threatened, including by fisheries bycatch. Accurate understanding of offshore distribution of seabirds is crucial to address this threat. Tracking technologies revolutionised insights into seabird distributions but tracking data may contain a variety of biases. We tracked two threatened seabirds (Salvin’s Albatross Thalassarche salvini n = 60 and Black Petrel Procellaria parkinsoni n = 46) from their breeding colonies in Aotearoa (New Zealand) to their non-breeding grounds in South America, including Peru, while simultaneously completing seven surveys in Peruvian waters. We then used species distribution models to predict occurrence and distribution using either data source alone, and both data sources combined. Results showed seasonal differences between estimates of occurrence and distribution when using data sources independently. Combining data resulted in more balanced insights into occurrence and distributions, and reduced uncertainty. Most notably, both species were predicted to occur in Peruvian waters during all four annual quarters: the northern Humboldt upwelling system for Salvin’s Albatross and northern continental shelf waters for Black Petrels. Our results highlighted that relying on a single data source may introduce biases into distribution estimates. Our tracking data might have contained ontological and/or colony-related biases (e.g. only breeding adults from one colony were tracked), while our survey data might have contained spatiotemporal biases (e.g. surveys were limited to waters <200 nm from the coast). We recommend combining data sources wherever possible to refine predictions of species distributions, which ultimately will improve fisheries bycatch management through better spatiotemporal understanding of risks.

The Lower–Middle Ordovician (Ibexian, Whiterockian) sedimentary rocks exposed at Rancho Las Norias includes the informally named Las Norias formation, which consists of an intercalation of carbonate and clastic sediments with abundant marine fauna. These deposits occur as the most austral sedimentary rocks of Ordovician age for Laurentia, providing a critical link to understand the distribution of Ordovician marine faunas of North America. An investigation of the gastropod fauna from the upper portion of the Las Norias formation, Sonora, Mexico, is undertaken for the first time. The gastropod assemblage includes Maclurites acuminatus, ?Monitorella sp., Lecanospira sp., Malayaspira aff. M. rugosa, Lophospira perangulata, and Hormotoma? sp. This assemblage indicates a paleogeographic relationship with Laurentia, including the USA (Nevada), Canada (British Columbia, Newfoundland), Greenland, and the Argentine Precordillera.

Answer Set Programming, or ASP for short, has become a popular and sophisticated approach to declarative problem solving. Its popularity is due to its attractive modeling-grounding-solving workflow that provides an easy approach to problem solving, even for laypersons outside computer science. However, in contrast to ASP’s ease of use, the high degree of sophistication of the underlying technology makes it even hard for ASP experts to put ideas into practice whenever this involves modifying ASP’s machinery. For addressing this issue, this tutorial aims at enabling users to build their own ASP-based systems. More precisely, we show how the ASP system clingo can be used for extending ASP and for implementing customized special-purpose systems. To this end, we propose two alternatives. We begin with a traditional AI technique and show how metaprogramming can be used for extending ASP. This is a rather light approach that relies on clingo’s reification feature to use ASP itself for expressing new functionalities. The second part of this tutorial uses traditional programming (in Python) for manipulating clingo via its application programming interface. This approach allows for changing and controlling the entire model-ground-solve workflow of ASP. Central to this is clingo’s new Application class that allows us to draw on clingo’s infrastructure by customizing processes similar to the one in clingo. For instance, we may apply manipulations to programs’ abstract syntax trees, control various forms of multi-shot solving, and set up theory propagators for foreign inferences. A cross-sectional structure, spanning meta as well as application programming, is clingo’s intermediate format, aspif, that specifies the interface among the underlying grounder and solver. We illustrate the aforementioned concepts and techniques throughout this tutorial by means of examples and several nontrivial case studies. In particular, we show how clingo can be extended by difference constraints and how guess-and-check programming can be implemented with both meta and application programming.

We present a general approach to planning with incomplete information in Answer Set Programming (ASP). More precisely, we consider the problems of conformant and conditional planning with sensing actions and assumptions. We represent planning problems using a simple formalism where logic programs describe the transition function between states, the initial states and the goal states. For solving planning problems, we use Quantified Answer Set Programming (QASP), an extension of ASP with existential and universal quantifiers over atoms that is analogous to Quantified Boolean Formulas (QBFs). We define the language of quantified logic programs and use it to represent the solutions different variants of conformant and conditional planning. On the practical side, we present a translation-based QASP solver that converts quantified logic programs into QBFs and then executes a QBF solver, and we evaluate experimentally the approach on conformant and conditional planning benchmarks.

Brucellosis remains one of the main zoonoses worldwide. Epidemiological data on human brucellosis in Spain are scarce. The objective of this study was to assess the epidemiological characteristics of inpatient brucellosis in Spain between 1997 and 2015. A retrospective longitudinal descriptive study was performed. Data were requested from the Health Information Institute of the Ministry of Health and Equality, which provided us with the Minimum Basic Data Set of patients admitted to the National Health System. We also obtained data published in the System of Obligatory Notifiable Diseases. A total of 5598 cases were registered. The period incidence rate was 0.67 (95% CI 0.65–0.68) cases per 100 000 person-years. We observed a progressive decrease in the number of cases and annual incidence rates. A total of 3187 cases (56.9%) came from urban areas. The group most at risk comprised men around the fifth decade of life. The average (±s.d.) hospital stay was 12.6 days (±13.1). The overall lethality rate of the cohort was 1.5%. The number of inpatients diagnosed with brucellosis decreased exponentially. The group of patients with the highest risk of brucellosis in our study was males under 45 years of age and of urban origin. The lethality rate has reduced to minimum values. It is probable that hospital discharge records could be a good database for the epidemiological analysis of the hospital management of brucellosis and offer a better information collection system than the notifiable diseases system (EDO in Spanish).

We describe eclingo, a solver for epistemic logic programs under Gelfond 1991 semantics built upon the Answer Set Programming system clingo. The input language of eclingo uses the syntax extension capabilities of clingo to define subjective literals that, as usual in epistemic logic programs, allow for checking the truth of a regular literal in all or in some of the answer sets of a program. The eclingo solving process follows a guess and check strategy. It first generates potential truth values for subjective literals and, in a second step, it checks the obtained result with respect to the cautious and brave consequences of the program. This process is implemented using the multi-shot functionalities of clingo. We have also implemented some optimisations, aiming at reducing the search space and, therefore, increasing eclingo ’s efficiency in some scenarios. Finally, we compare the efficiency of eclingo with two state-of-the-art solvers for epistemic logic programs on a pair of benchmark scenarios and show that eclingo generally outperforms their obtained results.

Globally, rock art is one of the most widely distributed manifestations of past human activity. Previous research, however, has tended to focus on the art rather than artists. Understanding which members of society participated in creating such art is crucial to interpreting its social implications and that of the sites at which it is found. This article presents the first application of a method—palaeodermatoglyphics—for the estimation of the sex and age of two later prehistoric individuals who left their fingerprints at the Los Machos rockshelter in southern Iberia. The method has the potential to illuminate the complex socio-cultural dimensions of rock art sites worldwide.

We describe the new version of the Planning Domain Definition Language (PDDL)-to-Answer Set Programming (ASP) translator plasp. First, it widens the range of accepted PDDL features. Second, it contains novel planning encodings, some inspired by Satisfiability Testing (SAT) planning and others exploiting ASP features such as well-foundedness. All of them are designed for handling multivalued fluents in order to capture both PDDL as well as SAS planning formats. Third, enabled by multishot ASP solving, it offers advanced planning algorithms also borrowed from SAT planning. As a result, plasp provides us with an ASP-based framework for studying a variety of planning techniques in a uniform setting. Finally, we demonstrate in an empirical analysis that these techniques have a significant impact on the performance of ASP planning.

Inspired by the biographical approach to the study of material culture, a radiocarbon dating programme was undertaken to explore the chronology and temporality of the megalithic monuments in south-eastern Iberia. Instead of one or two dates per tomb, the normal way of approaching this complex issue, we carried out a complete radiocarbon dating series of single tombs based on human remains. We focused our attention on four tholos-type tombs in the cemetery of El Barranquete (Almería, Spain). According to the new radiocarbon series modelled in a Bayesian framework, four main conclusions can be drawn: that the cemetery shows a very long period of funerary activity, which began in the late fourth millennium and ended in the last centuries of the second millennium cal bc; that continuity of ritual practices attained an unexpected importance during the Bronze Age; that interments, which fall into cultural periods that would be unthinkable if only the typological properties of the grave goods were considered, occurred; and that each tomb had a complex and very different biography.

This Research Communication reports interferences related to the administration of ivermectin in lactating dairy goats on the response of microbial tests for screening antibiotics in milk. Twenty-eight Murciano-Granadina goats, naturally infested with Sarcoptes scabiei var. caprae, were treated with a subcutaneous injection of ivermectin (200 µg/kg b.w.). To prevent re-infestation, a second dose was applied 7 d later. Individual milk samples were collected, daily, up to 15 d post-treatment. Milk samples were analysed by microbial inhibitor tests (BRT MRL, Delvotest SP-NT MCS and Eclipse 100) and ivermectin residues were quantified by HPLC. A large number of positive results were obtained for all microbial tests, especially on the first day after treatment (BRT MRL = 46·4%; Delvotest SP-NT MCS = 14·3%; and Eclipse 100 = 17·8%). However, the highest concentration of drug residues in milk (24·3 ng/ml) was detected on the tenth day after treatment, when positive outcomes were relatively lower (BRT MRL = 17·8%; Delvotest SP-NT MCS = 10·7%; and Eclipse 100 = 7·4%). Results herein suggest that factors related to the ivermectin treatment other than drug residues in milk, or alterations produced by the parasitic disease itself affecting the immune response of animals, could be the cause of false-positive results in microbial tests. It can be concluded that the application of ivermectin in dairy goats infested with sarcoptes mange during lactation produces persistent drug residues in milk, and could also cause false-positive results in microbial inhibitor tests for screening antibiotics.

Deficits in facial affect recognition have been repeatedly reported in schizophrenia patients. The hypothesis that this deficit is caused by poorly differentiated cognitive representation of facial expressions was tested in this study. To this end, performance of patients with schizophrenia and controls was compared in a new emotion-rating task. This novel approach allowed the participants to rate each facial expression at different times in terms of different emotion labels. Results revealed that patients tended to give higher ratings to emotion labels that did not correspond to the portrayed emotion, especially in the case of negative facial expressions (p < .001, η2 = .131). Although patients and controls gave similar ratings when the emotion label matched with the facial expression, patients gave higher ratings on trials with "incorrect" emotion labels (p s < .05). Comparison of patients and controls in a summary index of expressive ambiguity showed that patients perceived angry, fearful and happy faces as more emotionally ambiguous than did the controls (p < .001, η2 = .135). These results are consistent with the idea that the cognitive representation of emotional expressions in schizophrenia is characterized by less clear boundaries and a less close correspondence between facial configurations and emotional states.

Two new genera and four new species of bulbil-forming basidiomycetes are described. Phylogenetic analyses of nuLSU and ITS sequences place them in Cantharellales. A facultative lichenicolous species with yellow to orange-yellow bulbils from South America groups with the type of Burgella and is consequently described as B. lutea. The new species and genus Burgellopsis nivea is introduced for material from Scotland with white bulbils overgrowing saxicolous lichens. An obligate lichenicolous species with particularly large, applanate bulbils developing over Peltigerales in South America could not be placed accurately using ITS sequences and is described as the new species and genus Bulbilla applanata. A European species with brown, facultatively lichenicolous bulbils grouped with Ceratobasidium and Thanatephorus species and is described as the new Ceratobasidium bulbillifaciens.