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Answer Set Programming (ASP) is a logic programming paradigm featuring a purely declarative language with comparatively high modeling capabilities. Indeed, ASP can model problems in NP in a compact and elegant way. However, modeling problems beyond NP with ASP is known to be complicated, on the one hand, and limited to problems in {\Sigma}^P_2 on the other. Inspired by the way Quantified Boolean Formulas extend SAT formulas to model problems beyond NP, we propose an extension of ASP that introduces quantifiers over stable models of programs. We name the new language ASP with Quantifiers (ASP(Q)). In the paper we identify computational properties of ASP(Q); we highlight its modeling capabilities by reporting natural encodings of several complex problems with applications in artificial intelligence and number theory; and we compare ASP(Q) with related languages. Arguably, ASP(Q) allows one to model problems in the Polynomial Hierarchy in a direct way, providing an elegant expansion of ASP beyond the class NP. Under consideration for acceptance in TPLP., Comment: Paper presented at the 35th International Conference on Logic Programming (ICLP 2019), Las Cruces, New Mexico, USA, 20-25 September 2019, 16 pages

Background In the warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome, variable phenotypic expression may delay diagnosis. Panleukopenia, malignancy, and chronic lung disease all affect morbidity and mortality risks. Routinely used treatments include immunoglobulins, granulocyte-colony stimulating factor (G-CSF), and antibiotics; recent trials with a target C-X-C chemokine receptor type 4 (CXCR4) antagonist show promising results. Objective We sought to characterize the largest cohort of patients with WHIM and evaluate their diagnostic and therapeutic management. Methods Data were collected from an international cohort of 18 patients with CXCR4 mutations. Results The clinical features manifested at 2.2 ± 2.6 years of age, whereas the disease diagnosis was delayed until 12.5 ± 10.4 years of age. Patients with WHIM commonly presented with a severe bacterial infection (78%). Pneumonia recurrence was observed in 61% of patients and was complicated with bronchiectasis in 27%. Skin warts were observed in 61% of patients at a mean age of 11 years, whereas human papilloma virus (HPV)-related malignancies manifested in 16% of patients. All the patients had severe neutropenia (195 ± 102 cells/mm3 at onset), whereas lymphopenia and hypogammaglobulinemia were detected in 88% and 58% of patients, respectively. Approximately 50% of patients received antibiotic prophylaxis, whereas G-CSF and immunoglobulin treatments were used in 72% and 55% of patients, respectively. Conclusions The WHIM syndrome onsets early in life and should be suspected in patients with chronic neutropenia. Patients with WHIM need careful monitoring and timely intervention for complications, mainly lung disease and HPV-related malignancies. We suggest that immunoglobulin therapy should be promptly considered to control the frequency of bacterial infections and prevent chronic lung damage.

Unit testing frameworks are nowadays considered a best practice, foregone in almost all modern software development processes, to achieve rapid development of correct specifications. The first unit testing specification language for Answer Set Programming (ASP) was proposed in 2011 as a feature of the ASPIDE development environment. Later, a more portable unit testing language was included in the LANA annotation language. In this paper we propose a revisited unit testing specification language that allows one to inline tests within ASP program and an ASP-based test execution mechanism. Moreover, we present a programming environment supporting test driven development (TDD) of ASP programs with our language.

Answer Set Programming (ASP) is a well-established paradigm for declarative programming and nonmonotonic reasoning. ASP allows for flexible modeling using rules. ASP rules induce a set of intended models called answer sets. Incoherence, the non-existence of answer sets, is therefore a feature of ASP, indicating that the rules admit no intended models. However, this feature can also be problematic in certain circumstances: errors that cause incoherence are notoriously difficult to debug, and query answering will not provide any meaningful answers for incoherent programs. Paracoherent semantics have been suggested as a remedy. They extend the classical notion of answer sets to draw meaningful conclusions also from incoherent programs. However, paracoherent semantics have essentially been inapplicable in practice, due to the lack of efficient algorithms and implementations. In this paper, this lack is addressed, and several different algorithms to compute semi-stable and semi-equilibrium models are proposed and implemented within an answer set solving framework. A key role in the framework is played by syntactic program transformations that allow for characterizing paracoherent semantics in terms of the answer sets of transformed programs. Apart from existing transformations from the literature, a novel transformation is also proposed, which provides an alternative characterization of paracoherent semantics in terms of (extended) externally supported models. Notably, the new transformation is more compact than the existing ones, and brings performance benefits. An extensive empirical performance comparison among the algorithms on benchmarks from ASP competitions and a real-world use case is given as well. It shows not only that the methods developed in this paper lead to practically effective systems, but also show a clear advantage of the methods that rely on (extended) externally supported models.