The KB paradigm and its application to interactive configuration

The knowledge base paradigm aims to express domain knowledge in a rich formal language, and to use this domain knowledge as a knowledge base to solve various problems and tasks that arise in the domain by applying multiple forms of inference. As such, the paradigm applies a strict separation of concerns between information and problem solving. In this paper, we analyze the principles and feasibility of the knowledge base paradigm in the context of an important class of applications: interactive configuration problems. In interactive configuration problems, a configuration of interrelated objects under constraints is searched, where the system assists the user in reaching an intended configuration. It is widely recognized in industry that good software solutions for these problems are very difficult to develop. We investigate such problems from the perspective of the KB paradigm. We show that multiple functionalities in this domain can be achieved by applying different forms of logical inferences on a formal specification of the configuration domain. We report on a proof of concept of this approach in a real-life application with a banking company. To appear in Theory and Practice of Logic Programming (TPLP).Comment: To appear in Theory and Practice of Logic Programming (TPLP

On the Relationship between Logical Bayesian Networks and Probabilistic Logic Programming Based on the Distribution Semantics

A significant part of current research on (inductive) logic programming deals with probabilistic logical models. Over the last decade many logics or languages for representing such models have been introduced. There is currently a great need for insight into the relationships between all these languages. One kind of languages are those that extend probabilistic models with elements of logic, such as the language of Logical Bayesian Networks (LBNs). Some other languages follow the converse strategy of extending logic programs with a probabilistic semantics, often in a way similar to that of Sato's distribution semantics. In this paper we study the relationship between the language of LBNs and languages based on the distribution semantics. Concretely, we define a mapping from LBNs to theories in the Independent Choice Logic (ICL). We also show how this mapping can be used to learn ICL theories from data.status: publishe

Unfounded Sets for Disjunctive Logic Programs with Arbitrary Aggregates

Abstract. Aggregates in answer set programming (ASP) have recently been studied quite intensively. The main focus of previous work has been on defining suitable semantics for programs with arbitrary, potentially recursive aggregates. By now, these efforts appear to have converged. On another line of research, the relation between unfounded sets and (aggregate-free) answer sets has lately been rediscovered. It turned out that most of the currently available answer set solvers rely on this or closely related results (e.g., loop formulas). In this paper, we unite these lines and give a new definition of unfounded sets for disjunctive logic programs with arbitrary, possibly recursive aggregates. While being syntactically somewhat different, we can show that this definition properly generalizes all main notions of unfounded sets that have previously been defined for fragments of the language. We demonstrate that, as for restricted languages, answer sets can be crisply characterized by unfounded sets: They are precisely the unfounded-free models. This result can be seen as a confirmation of the robustness of the definition of answer sets for arbitrary aggregates. We also provide a comprehensive complexity analysis for unfounded sets, and study its impact on answer set computation.

Well-Supported Semantics for Logic Programs with Generalized Rules

Abstract. Logic programming under the stable model semantics has been extended to arbitrary formulas. A question of interest is how to characterize the property of well-supportedness, in the sense of Fages, which has been considered a cornerstone in answer set programming. In this paper, we address this issue by considering general logic programs, which consist of disjunctive rules with arbitrary propositional formulas in rule bodies. We define the justified stable semantics for these programs, propose a general notion of well-supportedness, and show the relationships between the two. We address the issue of computational complexity for various classes of general programs. Finally, we show that previously proposed well-supported semantics for aggregate programs and description logic programs are rooted in the justified stable semantics of general programs.

Recursive Aggregates in Disjunctive Logic Programs: Semantics and Complexity

Abstract. The addition of aggregates has been one of the most relevant enhancements to the language of answer set programming (ASP). They strengthen the modeling power of ASP, in terms of concise problem representations. While many important problems can be encoded using nonrecursive aggregates, some relevant examples lend themselves for the use of recursive aggregates. Previous semantic definitions typically agree in the nonrecursive case, but the picture is less clear for recursion. Some proposals explicitly avoid recursive aggregates, most others differ, and many of them do not satisfy desirable criteria, such as minimality or coincidence with answer sets in the aggregate-free case. In this paper we define a semantics for disjunctive programs with arbitrary aggregates (including monotone, antimonotone, and nonmonotone aggregates). This semantics is a fully declarative, genuine generalization of the answer set semantics for disjunctive logic programming (DLP). It is defined by a natural variant of the Gelfond-Lifschitz transformation, and treats aggregate and non-aggregate literals in a uniform way. We prove that our semantics guarantees the minimality (and therefore the incomparability) of answer sets, and demonstrate that it coincides with the standard answer set semantics on aggregate-free programs. Finally we analyze the computational complexity of this language, paying particular attention to the impact of syntactical restrictions on programs.

Adjunctive everolimus therapy for tuberous sclerosis complex-associated refractory seizures: Results from the postextension phase of EXIST-3

Objective Epilepsy is highly prevalent in patients with tuberous sclerosis complex (TSC). Everolimus showed higher efficacy than placebo for seizures in the primary analysis of the EXIST-3 study. Here, we present the long-term outcomes of everolimus at the end of the postextension phase (PEP; data cutoff date: October 25, 2017). Methods After completion of the extension phase, patients were invited to continue everolimus in the PEP with everolimus (targeted trough concentration = 5-15 ng/ml, investigator-judged). Efficacy assessments included changes in seizure status during the PEP collected at 12-week intervals as parent/caregiver-reported data through a structured questionnaire. Results Among 361 patients, 343 entered the extension phase and 249 entered the PEP. After 12 weeks in the PEP, 18.9% (46/244) of patients were seizure-free since the last visit of the extension phase and 64.8% (158/244) had a stable/improved seizure status. At 24 weeks, the corresponding percentages were 18.2% (42/231) and 64.5% (149/231). Among 244 patients, the response rate was 32.8% (80/244) during the 12-week maintenance period of the core phase and 63.9% (156/244) at the end of the extension phase. Of the 149 responders at the end of the extension phase, 70.5% were seizure-free or had stable/improved seizure status. Long-term efficacy data showed persistent responses were observed in 183 of 361 patients (50.7%); 63.9% of these patients had a response that lasted at least 48 weeks. The most frequent Grade 3-4 adverse events (>= 2% incidence) reported throughout the study were pneumonia, status epilepticus, seizure, stomatitis, neutropenia, and gastroenteritis. Four patients died during the study. Significance The final analysis of EXIST-3 demonstrated the sustained efficacy of everolimus as adjunctive therapy in patients with TSC-associated treatment-refractory seizures, with a tolerable safety profile