This note presents a historical survey of informal semantics that are associated with logic programming under answer set semantics. We review these in uniform terms and align them with two paradigms: Answer Set Progra...
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In the field of normative multiagent systems, the relationship between a game structure and its underpinning agent interaction rules is hardly ever addressed in a systematic manner. In this work, we introduce the Acti...
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ISBN:
(纸本)9781643682112;9781643682105
In the field of normative multiagent systems, the relationship between a game structure and its underpinning agent interaction rules is hardly ever addressed in a systematic manner. In this work, we introduce the Action Situation Language (ASL), inspired by Elinor Ostrom's Institutional Analysis and Development framework, to bridge the gap between games and rules. The ASL provides a syntax for the description of agent interactions, and is complemented by an engine that automatically provides semantics for them as extensive-form games. The resulting games can then be analysed using standard game-theoretical solution concepts, hence allowing any community of agents to automatically perform what-if analysis of potential new interaction rules.
The equational unification problem, where the underlying equational theory may be given as the union of component equational theories, appears often in practice in many fields such as automated reasoning, logic progra...
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ISBN:
(纸本)9783030684457;9783030684464
The equational unification problem, where the underlying equational theory may be given as the union of component equational theories, appears often in practice in many fields such as automated reasoning, logic programming, declarative programming, and the formal analysis of security protocols. In this paper, we investigate the unification problem in the non-disjoint union of equational theories via the combination of hierarchical unification procedures. In this context, a unification algorithm known for a base theory is extended with some additional inference rules to take into account the rest of the theory. We present a simple form of hierarchical unification procedure. The approach is particularly well-suited for any theory where a unification procedure can be obtained in a syntactic way using transformation rules to process the axioms of the theory. Hierarchical unification procedures are exemplified with various theories used in protocol analysis. Next, we look at modularity methods for combining theories already using a hierarchical approach. In addition, we consider a new complexity measure that allows us to obtain terminating (combined) hierarchical unification procedures.
This paper aims to bridge this gap between neuro-symbolic learning (NSL) and graph neural networks (GNN) approaches and provide a comparative study. We argue that the natural evolution of NSL leads to GNNs, while the ...
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ISBN:
(纸本)9781577358664
This paper aims to bridge this gap between neuro-symbolic learning (NSL) and graph neural networks (GNN) approaches and provide a comparative study. We argue that the natural evolution of NSL leads to GNNs, while the logic programming foundations of NSL can bring powerful tools to improve the way information is represented and pre-processed for the GNN. In order to make this comparison, we propose HetSAGE, a GNN architecture that can efficiently deal with the resulting heterogeneous graphs that represent typical NSL learning problems. We show that our approach outperforms the state-of-the-art on 3 NSL tasks: CORA, MUTA188 and MovieLens.
Smart environments enabled by the Internet of Things aim at improving our daily lives by automatically tuning ambient parameters and by achieving energy savings through self-managing cyber-physical systems. Commercial...
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ISBN:
(纸本)9781665412520
Smart environments enabled by the Internet of Things aim at improving our daily lives by automatically tuning ambient parameters and by achieving energy savings through self-managing cyber-physical systems. Commercial solutions, however, only permit setting simple target goals on those parameters and do not mediate between conflicting goals among different users and/or system administrators, nor across different IoT verticals. In this article, we propose a declarative approach (and its open-source Prolog prototype) to represent smart environments, user-set goals and customisable mediation policies to reconcile contrasting goals across multiple IoT systems.
Non-termination is an unwanted program property (considered a bug) for some software systems, and a safety property for other systems. In either case, automated discovery of preconditions for non-termination is of int...
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ISBN:
(纸本)9783030921248;9783030921231
Non-termination is an unwanted program property (considered a bug) for some software systems, and a safety property for other systems. In either case, automated discovery of preconditions for non-termination is of interest. We introduce NTHORN, a fast lightweight non-termination analyser, able to deduce non-trivial sufficient conditions for non-termination. Using Constrained Horn Clauses (CHCs) as a vehicle, we show how established techniques for CHC program transformation and abstract interpretation can be exploited for the purpose of non-termination analysis. NTHORN is comparable in power to the state-of-the-art non-termination analysis tools, as measured on standard competition benchmark suites (consisting of integer manipulating programs), while typically solving problems an order of magnitude faster.
Two fundamental challenges in program synthesis, i.e. learning programs from specifications, are (1) program correctness and (2) search efficiency. We claim logical constraints can address both: (1) by expressing stro...
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ISBN:
(纸本)9781577358664
Two fundamental challenges in program synthesis, i.e. learning programs from specifications, are (1) program correctness and (2) search efficiency. We claim logical constraints can address both: (1) by expressing strong requirements on solutions and (2) due to being effective at eliminating non solutions. When learning from examples, a hypothesis failing on an example means that (a class of) related programs fail as well. We encode these classes into constraints, thereby pruning away many a failing hypothesis. We are expanding this method with failure explanation: identify failing sub-programs the related programs of which can be eliminated as well. In addition to reasoning about examples, programming involves ensuring general properties are not violated. Inspired by the synthesis of functional programs, we intend to encode correctness properties as well as runtime complexity bounds into constraints.
PRoB provides a constraint solver for the B-method written in Prolog and optionally can make use of different backends based on SAT or SMT solving. One such solver integration translates B and Event-B operators to SMT...
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ISBN:
(纸本)9783030852481;9783030852474
PRoB provides a constraint solver for the B-method written in Prolog and optionally can make use of different backends based on SAT or SMT solving. One such solver integration translates B and Event-B operators to SMT-LIB using the C interface of the Z3 solver. This translation uses quantifiers to axiomatise operators when translating to SMT-LIB, which are not well-handled by Z3. Several relational constraints such as the transitive closure are not supported since their translations were too involved. In this paper, we substantially improve the translation to SMT-LIB by employing a more constructive rather than axiomatised style using Z3's lambda functions. Thereby, we are able to translate more set-theoretic B and Event-B operators to SMT-LIB, and improve the overall performance. We further extend PRoB's interface to Z3 to run different solver configurations in parallel, e.g., either using the former or new translation. Empirical results show that the new translation to SMT-LIB and the parallel integration of different configurations of the Z3 solver have improved the performance of constraint solving.
Recent research suggests that systematic generalization in natural language understanding remains a challenge for state-of-the-art neural models such as Transformers and Graph Neural Networks. To tackle this challenge...
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ISBN:
(纸本)9781713845393
Recent research suggests that systematic generalization in natural language understanding remains a challenge for state-of-the-art neural models such as Transformers and Graph Neural Networks. To tackle this challenge, we propose Edge Transformer, a new model that combines inspiration from Transformers and rule-based symbolic AI. The first key idea in Edge Transformers is to associate vector states with every edge, that is, with every pair of input nodes-as opposed to just every node, as it is done in the Transformer model. The second major innovation is a triangular attention mechanism that updates edge representations in a way that is inspired by unification from logic programming. We evaluate Edge Transformer on compositional generalization benchmarks in relational reasoning, semantic parsing, and dependency parsing(1). In all three settings, the Edge Transformer outperforms Relation-aware, Universal and classical Transformer baselines.
Reaction Systems (RSs) are a successful natural computing framework inspired by chemical reaction networks. A RS consists of a set of entities and a set of reactions. Entities can enable or inhibit each reaction, and ...
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ISBN:
(纸本)9783030904258;9783030904241
Reaction Systems (RSs) are a successful natural computing framework inspired by chemical reaction networks. A RS consists of a set of entities and a set of reactions. Entities can enable or inhibit each reaction, and are produced by reactions or provided by the environment. In a previous paper, we defined an original labelled transition system (LTS) semantics for RSs in the structural operational semantics (SOS) style. This approach has several advantages: (i) it provides a formal specification of the RS dynamics that enables the reuse of many formal analysis techniques and favors the implementation of tools, and (ii) it facilitates the definition of extensions of the RS framework by simply modifying some of the SOS rules in a modular way. In this paper, we demonstrate the extensibility of the framework by defining two quantitative variants of RSs: with reaction delays/durations, and with concentration levels. We provide a prototype logic programming implementation and apply our tool to a RS model of Th cells differentiation in the immune system.
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