Author name cluster

Giuseppe Mazzotta

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8 papers

2 author rows

AAAI Conference 2026 Conference Paper

2-ASP(Q) Solving Based on CEGAR

Andrea Cuteri
Giuseppe Mazzotta
Francesco Ricca

The ASP(Q) language extends Answer Set Programming (ASP) with Quantifiers that operate over answer sets. Thus, ASP(Q) facilitates a more natural encoding of problems whose complexity exceeds NP within the ASP framework. In this paper we focus on ASP(Q) programs with two quantifiers, i.e., 2-ASP(Q) programs, which can be used to model problems in the second level of the Polynomial Hierarchy. In particular, we propose an approach for evaluating 2-ASP(Q) programs that is inspired by Counterexample Guided Abstraction Refinement (CEGAR). Unlike existing state-of-the-art ASP(Q) solvers, which are typically based on QBF solvers, our new approach leverages ASP solvers, and suffers no overhead due to the effects of translating ASP(Q) in QBF. Experimental results demonstrate that our technique consistently outperforms state-of-the-art ASP(Q) solvers, across benchmark problems located at the second level of the polynomial hierarchy.

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AAAI Conference 2026 Conference Paper

Enumerating Minimal Unsatisfiable Cores of LTLf Formulae

Antonio Ielo
Giuseppe Mazzotta
Rafael Peñaloza
Francesco Ricca

Linear Temporal Logic over finite traces (LTLf) is a widely used formalism with applications in AI, process mining, model checking, and more. The primary reasoning task for LTLf is satisfiability checking; yet, the recent focus on explainable AI has increased interest in analyzing inconsistent formulae, making the enumeration of minimal explanations for unsatisfiability a relevant task also for LTLf. We introduce a novel technique for enumerating minimal unsatisfiable cores (MUCs) of an LTLf specification. The main idea is to encode an LTLf formula into an Answer Set Programming (ASP) specification, such that the minimal unsatisfiable subsets (MUSes) of the ASP program directly correspond to the MUCs of the original LTLf specification. Leveraging recent advancements in ASP solving yields an MUC enumerator achieving good performance in experiments conducted on established benchmarks from the literature.

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KR Conference 2025 Conference Paper

A Novel Framework for Reasoning over Optimization Problems in Probabilistic Answer Set Programming

Damiano Azzolini
Giuseppe Mazzotta
Francesco Ricca
Fabrizio Riguzzi

Probabilistic logic-based languages offer an expressive framework for encoding uncertain information in a human-interpretable way. Among existing formalisms, Probabilistic Answer Set Programming (PASP) stands out for its ease of modeling complex scenarios. The current definition of PASP is limited to programs consisting of disjunctive rules and probabilistic facts only. To enhance the expressivity of the framework, we introduce Optimal Probabilistic Answer Set Programming, which extends the language by allowing the inclusion of weak constraints within PASP specifications. We motivate this extension through some real-world application scenarios and present a detailed computational complexity analysis for both the inference and Most Probable Explanation (MPE) tasks.

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ECAI Conference 2025 Conference Paper

An Algebraic View of MAP Inference in Probabilistic Answer Set Programs

Damiano Azzolini
Giuseppe Mazzotta
Francesco Ricca
Fabrizio Riguzzi

Maximum-a-Posteriori (MAP) inference is a crucial problem in Artificial Intelligence, which requires both marginalization and maximization, and asks for the most probable value for a given set of variables such that an evidence holds. Several languages within the Statistical Relational Artificial Intelligence landscape support the encoding of MAP. Here, we focus on Probabilistic Answer Set Programming, consider the credal and smProbLog semantics, and introduce a three-level algebraic model counting representation for MAP. We implemented our approach on top of a state-of-the-art solver and compared it with existing solutions, showing the competitive performance of our proposal, even against less general tools.

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IJCAI Conference 2025 Conference Paper

Most Probable Explanation in Probabilistic Answer Set Programming

Damiano Azzolini
Giuseppe Mazzotta
Francesco Ricca
Fabrizio Riguzzi

Most Probable Explanation (MPE) is a fundamental problem in statistical relational artificial intelligence. In the context of Probabilistic Answer Set Programming (PASP), solving MPE is still an open research problem. In this paper, we present three novel approaches for solving the MPE task in PASP that are based on: i) Algebraic Model Counting, ii) Answer Set Programming (ASP), and iii) ASP with quantifiers (ASP(Q)). These approaches are implemented and evaluated against existing solvers across different datasets and configurations. Empirical results demonstrate that the novel solutions consistently outperform existing alternatives for non-stratified programs.

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KR Conference 2024 Conference Paper

Blending Grounding and Compilation for Efficient ASP Solving

Carmine Dodaro
Giuseppe Mazzotta
Francesco Ricca

Answer Set Programming (ASP) is a widely recognized formalism for Knowledge Representation and Reasoning. Traditional ASP systems, that employ the ground and solve architecture, are subject to the grounding bottleneck (i. e. , variable-elimination can exhaust all computational resources). Compilation-based approaches have recently demonstrated how grounding can be effectively bypassed by compiling rules into propagators that simulate them. However, compiling an entire ASP program is not always advantageous. In this paper, we present both a program rewriting technique and an algorithm for the compilation of grounding that allow for unrestricted blending of grounding and compilation. We implement these techniques in a hybrid ASP system that compares favourably with state-of-the-art ASP solvers on established benchmarks.

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ECAI Conference 2023 Conference Paper

Compilation of Tight ASP Programs

Carmine Dodaro
Giuseppe Mazzotta
Francesco Ricca

Answer Set Programming (ASP) is a well-known AI formalism. Traditional ASP systems, that follow the “ground&solve” approach, are intrinsically limited by the so-called grounding bottleneck. Basically, the grounding step (i. e. , variable-elimination) can be computationally expensive, and even unfeasible in several cases of practical interest. Recent work demonstrated that the grounding bottleneck can be partially overcome by compiling in external propagators subprograms acting as constraints. In this paper a novel compilation technique is presented that can be applied to tight normal programs; thus, the class of ASP programs that can be compiled is extended beyond constraints. The approach is implemented in the new system PROASP. PROASP skips entirely the grounding phase and performs solving by injecting custom propagators in GLUCOSE. An experiment, conducted on grounding-intensive ASP benchmarks, shows that PROASP is capable of solving instances that are out of reach for state-of-the-art ASP systems.

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AAAI Conference 2022 Conference Paper

Compilation of Aggregates in ASP Systems

Giuseppe Mazzotta
Francesco Ricca
Carmine Dodaro

Answer Set Programming (ASP) is a well-known declarative AI formalism for knowledge representation and reasoning. State-of-the-art ASP implementations employ the ground&solve approach, and they were successfully applied to industrial and academic problems. Nonetheless there are classes of ASP programs whose evaluation is not efficient (sometimes not feasible) due to the combinatorial blow-up of the program produced by the grounding step. Recent research suggests that compilation-based techniques can mitigate the grounding bottleneck problem. However, no compilationbased technique has been developed for ASP programs that contain aggregates, which are one of the most relevant and commonly-employed constructs of ASP. In this paper, we propose a compilation-based approach for ASP programs with aggregates. We implement it on top of a state-of-theart ASP system, and evaluate the performance on publiclyavailable benchmarks. Experiments show our approach is effective on ground-intensive ASP programs.

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