Europe
Argumentative Approaches to Reasoning with Maximal Consistency
Arieli, Ofer (The Academic College of Tel-Aviv) | Strasser, Christian (Ruhr University Bochum)
Reasoning with the maximally consistent subsets (MCS) of the premises is awell-known approach for handling contradictory information. We introduce two argumentation-based methods for doing so: a declarative approach that is related to Dung-style semantics for abstract argumentation, and a computational approach that is based on extensions of Gentzen-type proofs systems. This brings about a new perspective on reasoning with MCS which shows a strong link between the latter and argumentation systems, and which can be extended to related formalisms. A by-product of this is the introduction of a dynamic proof system for classical logic and rebuttal attacks, which is sound and complete with respect to Dung's stable semantics for the associated argumentation framework.
Unsupervised Grounding of Textual Descriptions of Object Features and Actions in Video
Alomari, Muhannad (University of Leeds) | Chinellato, Eris (University of Leeds) | Gatsoulis, Yiannis (University of Leeds) | Hogg, David C. (University of Leeds) | Cohn, Anthony G. (University of Leeds)
Learning linguistic and visual concepts from videos and textual the word blue is represented by a subset of the colour feature descriptions without having a predefined set of representations space). We will refer to the words that have visual representations is a challenging yet important task. For example, as concrete linguistic concepts (e.g. the word humans are born without the knowledge of how many representations blue has a representation in the colour space, therefore, blue for directions there are in the world, or how they is a concrete linguistic concept). We will refer to these visual are described in natural language. In some situations, it is representations as visual concepts (e.g. the blue colour better to use the 4 directions representation (front, right, left, in the colour feature space is a visual concept). Finally, we back), in others, one can use the 8 directions (front, front will use the term groundings to refer to the connections between right, right, etc.). Humans are capable of learning these different the different linguistic concepts and visual concepts.
Probabilistic Models over Weighted Orderings: Fixed-Parameter Tractable Variable Elimination
Lukasiewicz, Thomas (University of Oxford) | Martinez, Maria Vanina (Universidad Nacional del Sur) | Poole, David (University of British Columbia) | Simari, Gerardo Ignacio (Universidad Nacional del Sur)
Probabilistic models with weighted formulas, known as Markov models or log-linear models, are used in many domains. Recent models of weighted orderings between elements that have been proposed as flexible tools to express preferences under uncertainty, are also potentially useful in applications like planning, temporal reasoning, and user modeling. Their computational properties are very different from those of conventional Markov models; because of the transitivity of the โless thanโ relation, standard methods that exploit structure of the models, such as variable elimination, are not directly applicable, as there are no conditional independencies between the orderings within connected components. The best known algorithms for general inference inthese models are exponential in the number of statements. Here, we present the first algorithms that exploit the available structure. We begin with the special case of models in the form of chains; we present an exact O(n^3) algorithm, where n is the total number of elements. Next, we generalize this technique to models in which the set of statements are comprised of arbitrary sets of atomic weighted preference formulas (while the query and evidence are conjunctions of atomic preference formulas), and the resulting exact algorithm runs in time O(m * n^2 * n^c), where m is the number of preference formulas, n is the number of elements, and c is the maximum number of elements in a linear cut (which depends both on the structure of the model and the order in which the elements are processed)โtherefore, this algorithm is tractable for cases in which c can be bounded to a low value. Finally, we report on the results of an empirical evaluation of both algorithms, showing how they scale with reasonably-sized models.
Bayesian Deduction with Subjective Opinions
Ivanovska, Magdalena (University of Oslo) | Jรธsang, Audun (University of Oslo) | Sambo, Francesco ( University of Padova )
Subjective opinions can represent uncertain probabilistic information of any kind, minor or major A Bayesian network (BN) is a compact representation of a imprecision and even total ignorance about the probability joint probability distribution in the form of a directed acyclic distribution, by varying the uncertainty mass between 0 and graph (DAG) with random variables as nodes, and a set 1. By simply substituting every input conditional probability of conditional probability distributions associated with each distribution in a BN with a subjective opinion, we obtain node representing the probabilistic connection of the node what we call a subjective Bayesian network.
Model Checking Well-Behaved Fragments of HS: The (Almost) Final Picture
Molinari, Alberto (University of Udine) | Montanari, Angelo (University of Udine) | Peron, Adriano (University of Napoli) | Sala, Pietro (University of Verona)
Model checking is one of the most powerful and widespread tools for system verification with applications in many areas of computer science and artificial intelligence. The large majority of model checkers deal with properties expressed in point-based temporal logics, such as LTL and CTL. However, there exist relevant properties of systems which are inherently interval-based. Model checking algorithms for interval temporal logics (ITLs) have recently been proposed to check interval properties of computations. As the model checking problem for full Halpern and Shoham's ITL (HS for short) turns out to be decidable, but computationally heavy, research has focused on its well-behaved fragments. In this paper, we provide an almost final picture of the computational complexity of model checking for HS fragments with modalities for (a subset of) Allen's relations meets , met by , starts , and ends .
Encoding Large RCC8 Scenarios Using Rectangular Pseudo-Solutions
Long, Zhiguo (University of Technology Sydney) | Schockaert, Steven (Cardiff University) | Li, Sanjiang (University of Technology Sydney)
Most approaches in the field of qualitative spatial reasoning (QSR) use constraint networks to encode spatial scenarios. The size of these networks is quadratic in the number of variables, which has severely limited the real-world application of QSR. In this paper, we propose another representation of spatial scenarios, in which each variable is associated with one or more rectangles. Instead of requiring these rectangles to define a solution of the corresponding constraint network, we construct sequences of rectangles that define partial solutions to progressively weaker constraint networks. We present experimental results that illustrate the effectiveness of this strategy.
Quantifying Conflicts for Spatial and Temporal Information
Condotta, Jean-Franรงois (Centre National de la Recherche Scientifique (CNRS) and Universitรฉ d'Artois) | Raddaoui, Badran (University of Poitiers) | Salhi, Yakoub (Centre National de la Recherche Scientifique (CNRS) and Universitรฉ d'Artois)
This paper tackles the problem of evaluating the degree of inconsistency in spatial and temporal qualitative reasoning. We first introduce postulates to propose a formal framework for measuring inconsistency in this context. Then, we provide two inconsistency measures that can be useful in various AI applications. The first one is based on the number of constraints that we need to relax to get a consistent qualitative constraint network. The second inconsistency measure is based on variable restrictions to restore consistency. It is defined from the minimum number of variables that we need to ignore to recover consistency. We show that our proposed measures satisfy required postulates and other appropriate properties. Finally, we discuss the impact of our inconsistency measures on belief merging in qualitative reasoning.
A SAT Approach for Maximizing Satisfiability in Qualitative Spatial and Temporal Constraint Networks
Condotta, Jean-Franรงois (Universitรฉ d'Artois) | Nouaouri, Issam (Universitรฉ d'Artois) | Sioutis, Michael (Universitรฉ d'Artois)
In this paper, we focus on a recently introduced problem in the context of spatial and temporal qualitative reasoning, called the MAX-QCN problem. This problem involves obtaining a spatial or temporal configuration that maximizes the number of satisfied constraints in a qualitative constraint network (QCN). To efficiently solve the MAX-QCN problem, we introduce and study two families of encodings of the partial maximum satisfiability problem (PMAX-SAT). Each ofthese encodings is based on, what we call, a forbidden covering with regard to the composition table of the considered qualitative calculus. Intuitively, a forbidden covering allows us to express, in a more or less compact manner, the non-feasible configurations for three spatial or temporal entities.The experimentation that we have conducted with qualitative constraint networks from the Interval Algebra shows the interest of our approach.
On First-Order ฮผ-Calculus over Situation Calculus Action Theories
Calvanese, Diego (Free University of Bozen-Bolzano) | Giacomo, Giuseppe De (Sapienza University of Rome) | Montali, Marco (Free University of Bozen-Bolzano) | Patrizi, Fabio (Free University of Bozen-Bolzano)
In this paper we study verification of situation calculus action theories against first-order mu-calculus with quantification across situations. Specifically, we consider mu-La and mu-Lp, the two variants of mu-calculus introduced in the literature for verification of data-aware processes. The former requires that quantification ranges over objects in the current active domain, while the latter additionally requires that objects assigned to variables persist across situations. Each of these two logics has a distinct corresponding notion of bisimulation. In spite of the differences we show that the two notions of bisimulation collapse for dynamic systems that are generic, which include all those systems specified through a situation calculus action theory. Then, by exploiting this result, we show that for bounded situation calculus action theories, mu-La and mu-Lp have exactly the same expressive power. Finally, we prove decidability of verification of mu-La properties over bounded action theories, using finite faithful abstractions. Differently from the mu-Lp case, these abstractions must depend on the number of quantified variables in the mu-La formula.
Imperfect Information in Reactive Modules Games
Gutierrez, Julian (University of Oxford) | Perelli, Giuseppe (University of Oxford) | Wooldridge, Michael (University of Oxford)
Such a goal can represent either the behaviour model checking systems (e.g., MOCHA (Alur et al. 1998) of the computer system one wants to synthesize and Prism (Kwiatkowska, Norman, and Parker 2011)). Reactive (an automated design problem (Pnueli and Rosner 1989)) Modules supports succinct and high-level modelling or a particular system property which one wants to check of concurrent and multi-agent systems. In the games we (an automated verification problem (Clarke, Grumberg, and study, the preferences of system components are specified Peled 2000)). In this framework, it is assumed that the system by associating with each player in the game a temporal logic plays against an adversarial environment, that is, that (LTL) formula that the player desires to be satisfied. Reactive the goal of the environment is to prevent the system from Modules Games with perfect information (where each player achieving its goal. In game-theoretic terms, this means that can see the entire system state) have been extensively studied the problem is modelled as a zero-sum game, and hence that (Gutierrez, Harrenstein, and Wooldridge 2015a), but in its solution is given by the computation of a winning strategy this paper we focus on imperfect information cases. We study for either the system or the environment.