Natasha Alechina

University of Nottingham, Nottigham, England, United Kingdom

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Publications (86)7.7 Total impact

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    ABSTRACT: Due to their powerful knowledge representation formalism and associated inference mechanisms, ontology-based approaches have been increasingly adopted to formally represent domain knowledge. We propose the use of ontologies to advance knowledge-sharing on underutilized crops and propose how to integrate those ontologies with rules for added expressiveness. We first present a survey on using ontologies in the field of life-sciences with emphasis on crop-related ontologies, and justify why we need a new formalism. We then present the UC-ONTO (an Underutilized Crops Ontology) as a case study showing the integration of OWL (Web Ontology Language) ontologies with Semantic Web Rule Language (SWRL) rules.
    CEUR Workshop Proceedings of The Second International Workshop on Linked Data and Ontology in Practice, Chiang Mai, Thailand; 11/2014
  • Natasha Alechina, Mehdi Dastani, Brian Logan
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    ABSTRACT: We consider the problem of updating a multi-agent system with a set of conditional norms. A norm comes into effect when its condition becomes true, and imposes either an obligation or a prohibition on an agent which remains in force until a state satisfying a deadline condition is reached. If the norm is violated, a sanction is imposed on the agent. We define a notion of a normative update of a multi-agent system by a set of conditional norms, and study the problem of checking whether the agent(s) can bring about a state satisfying a property without incurring a specified number of sanctions.
    Proceedings of the Twenty-Third international joint conference on Artificial Intelligence; 08/2013
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    ABSTRACT: In many logic-based BDI agent programming languages, plan selection involves inferencing over some underlying knowledge representation. While context-sensitive plan selection facilitates the development of flexible, declarative programs, the overhead of evaluating repeated queries to the agent’s beliefs and goals can result in poor run time performance. In this paper we present an approach to multi-cycle query caching for logic-based BDI agent programming languages. We extend the abstract performance model presented in (Alechina et al. 2012) to quantify the costs and benefits of caching query results over multiple deliberation cycles. We also present results of experiments with prototype implementations of both single- and multi-cycle caching in three logic-based BDI agent platforms, which demonstrate that significant performance improvements are achievable in practice.
    Twenty-Seventh AAAI Conference on Artificial Intelligence (AAAI-13); 07/2013
  • Conference Paper: Minimal Preference Change
    Natasha Alechina, Fenrong Liu, Brian Logan
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    ABSTRACT: We propose a novel approach to preference change. We treat a set of preferences as a special kind of theory, and define minimal change contraction and revision operations in the spirit of minimal change as advocated by the Alchourron, Gardenfors, and Makinson (AGM) theory of belief revision. We characterise minimal contraction of preference sets by a set of postulates and prove a representation theorem. We also give a linear time algorithm which implements minimal contraction by a single preference. We also define minimal contraction by a set of preferences, and for a significant special case state postulates, prove a representation theorem, and provide an efficient algorithm implementing minimal contraction by a set of preferences.
    Proceedings of the Fourth International Workshop on Logic, Rationality and Interaction,, Hangzhou; 01/2013
  • Conference Paper: The logic of NEAR and FAR
    Heshan Du, Natasha Alechina, Kristin Stock, Mike Jackson
    COSIT 2013: Conference on Spatial Information Theory, Scarborough, UK; 09/2012
  • Thomas Ågotnes, Natasha Alechina
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    ABSTRACT: Coalition logic is currently one of the most popular logics for multi-agent systems. While logics combining coalitional and epistemic operators have received considerable attention, completeness results for epistemic extensions of coalition logic have so far been missing. In this paper we provide several such results and proofs. We prove completeness for epistemic coalition logic with common knowledge, with distributed knowledge, and with both common and distributed knowledge, respectively. Furthermore, we completely characterise the complexity of the satisfiability problem for each of the three logics.
    Proceedings of the 11th International Conference on Autonomous Agents and Multiagent Systems - Volume 2; 06/2012
  • Natasha Alechina, Mehdi Dastani, Brian Logan
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    ABSTRACT: Normative organisations provide a means to coordinate the activities of individual agents in multiagent settings. The coordination is realized at run time by creating obligations and prohibitions (norms) for individual agents. If an agent cannot meet an obligation or violates a prohibition, the organisation imposes a sanction on the agent. In this paper, we consider norm-aware agents that deliberate on their goals, norms and sanctions before deciding which plan to select and execute. A norm-aware agent is able to violate norms (accepting the resulting sanctions) if it is in the agent's overall interests to do so, e.g., if meeting an obligation would result in an important goal of the agent becoming unachievable. Programming norm-aware agents in conventional BDI-based agent programming languages is difficult, as they lack support for deliberating about goals, norms, sanctions and deadlines. We present the norm-aware agent programming language N-2APL. N-2APL is based on 2APL and provides support for beliefs, goals, plans, norms, sanctions and deadlines. We give the syntax and semantics of N-2APL, and show that N-2APL agents are rational in the sense of committing to a set of plans that will achieve the agent's most important goals and obligations by their deadlines while respecting its most important prohibitions.
    Proceedings of the 11th International Conference on Autonomous Agents and Multiagent Systems - Volume 2; 06/2012
  • Conference Paper: Consensus games
    Julian Zappala, Natasha Alechina, Brian Logan
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    ABSTRACT: Consensus Games (CGs) are a novel approach to modelling coalition formation in multi-agent systems inspired by threshold models in sociology. In a CG, each agent's degree of commitment to the coalitions in which it may participate is expressed as a quorum function. Agents are willing to form a coalition only if a quorum consensus can be achieved amongst all agents of the coalition.
    Proceedings of the 11th International Conference on Autonomous Agents and Multiagent Systems - Volume 3; 06/2012
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    ABSTRACT: This article describes results from a research project undertaken to explore the technical issues associated with integrating unstructured crowd sourced data with authoritative national mapping data. The ultimate objective is to develop methodologies to ensure the feature enrichment of authoritative data, using crowd sourced data. Users increasingly find that they wish to use data from both kinds of geographic data sources. Different techniques and methodologies can be developed to solve this problem. In our previous research, a position map matching algorithm was developed for integrating authoritative and crowd sourced road vector data, and showed promising results (Anand et al. 2010). However, especially when integrating different forms of data at the feature level, these techniques are often time consuming and are more computationally intensive than other techniques available. To tackle these problems, this project aims at developing a methodology for automated conflict resolution, linking and merging of geographical information from disparate authoritative and crowd-sourced data sources. This article describes research undertaken by the authors on the design, implementation, and evaluation of algorithms and procedures for producing a coherent ontology from disparate geospatial data sources. To integrate road vector data from disparate sources, the method presented in this article first converts input data sets to ontologies, and then merges these ontologies into a new ontology. This new ontology is then checked and modified to ensure that it is consistent. The developed methodology can deal with topological and geometry inconsistency and provide more flexibility for geospatial information merging.
    Transactions in GIS 01/2012; · 0.54 Impact Factor
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    Thomas Ågotnes, Natasha Alechina
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    ABSTRACT: Coalition logic is one of the most popular logics for multi-agent systems. While epistemic extensions of coalition logic have received much attention, existence of their complete axiomatisations has so far been an open problem. In this paper we settle several of those problems. We prove completeness for epistemic coalition logic with common knowledge, with distributed knowledge, and with both common and distributed knowledge, respectively.
    07/2011;
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    ABSTRACT: Facilities for handling plan execution failures are essential for agents which must cope with the effects of nondeterministic actions, and some form of failure handling can be found in most mature agent programming languages and platforms. While such features simplify the development of more robust agents, they make it hard to reason about the execution of agent programs, e.g., to verify their correctness. In this paper, we present an approach to the verification of agent programs which admit exceptional executions. We consider executions of the BDI-based agent programming language 3APL in which plans containing non-executable actions can be revised using plan revision rules, and present a logic for reasoning about normal and exceptional executions of 3APL programs. We provide a complete axiomatization for the logic and, using a simple example, show how to express properties of 3APL programs as formulas of the logic.
    Theoretical Computer Science 01/2011; 412:6115-6134. · 0.49 Impact Factor
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    Thomas Ågotnes, Natasha Alechina
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    ABSTRACT: In this paper we point out that standard PDL-like logics with intersection are useful for reasoning about game structures. In particular, they can express coalitional ability operators known from coalition logic and ATL. An advantage of standard, normal, modal logics is a well understood theoretical foundation and the availability of tools for automated verification and reasoning. We study a minimal variant, multi-modal K with intersection of modalities, interpreted over models corresponding to game structures. There is a restriction: we consider only game structures that are injective. We give a complete axiomatisation of the corresponding models, as well as a characterisation of key complexity problems. We also prove a representation theorem identifying the effectivity functions corresponding to injective games.
    Computational Logic in Multi-Agent Systems - 12th International Workshop, CLIMA XII, Barcelona, Spain, July 17-18, 2011. Proceedings; 01/2011
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    Konstantin Vikhorev, Natasha Alechina, Brian Logan
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    ABSTRACT: We present AgentSpeak(RT), a real-time BDI agent programming language based on AgentSpeak(L). AgentSpeak(RT) extends AgentSpeak intentions with deadlines which specify the time by which the agent should respond to an event, and priorities which specify the relative importance of responding to a particular event. The AgentSpeak(RT) interpreter commits to a priority-maximal set of intentions: a set of intentions which is maximally feasible while preferring higher priority intentions. We prove some properties of the language, such as guaranteed reactivity delay of the AgentSpeak(RT) interpreter and probabilistic guarantees of successful execution of intentions by their deadlines.
    10th International Conference on Autonomous Agents and Multiagent Systems (AAMAS 2011), Taipei, Taiwan, May 2-6, 2011, Volume 1-3; 01/2011
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    ABSTRACT: We present a sound and complete logic for automatic verification of simpleAPL programs. simpleAPL is a simplified version of agent programming languages such as 3APL and 2APL designed for the implementation of cognitive agents with beliefs, goals and plans. Our logic is a variant of PDL, and allows the specification of safety and liveness properties of agent programs. We prove a correspondence between the operational semantics of simpleAPL and the models of the logic for two example program execution strategies. We show how to translate agent programs written in simpleAPL into expressions of the logic, and give an example in which we show how to verify correctness properties for a simple agent program using theorem-proving.
    07/2010: pages 1-33;
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    Xiaofan Liu, Natasha Alechina, Brian Logan
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    ABSTRACT: Business processes are increasingly being expressed in declarative terms, as business rules which express obligations concerning conduct, action, practice or procedure regarding a particular business activity or sphere of operation. However, the leading standard for business rules, Semantics for Business Vocabulary and Business Rules (SBVR), leaves certain decisions concerning the precise syntax and semantics of business rules unspecified, for example, the scope and nesting of modalities and first order quantifiers, and the precise semantics of alethic and deontic modalities. In this paper, we propose a precise syntax and semantics for SBVR and present some complexity results for business rules with the proposed syntax and semantics.
    Knowledge-Based and Intelligent Information and Engineering Systems - 14th International Conference, KES 2010, Cardiff, UK, September 8-10, 2010, Proceedings, Part IV; 01/2010
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    Natasha Alechina, Brian Logan
    Proceedings of The Multi-Agent Logics, Languages, and Organisations Federated Workshops (MALLOW 2010), Lyon, France, August 30 - September 2, 2010; 01/2010
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    Natasha Alechina, Brian Logan
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    ABSTRACT: There exists a considerable body of work on epistemic logics for resource-bounded reasoners. In this paper, we concentrate on a less studied aspect of resource-bounded reason- ing, namely, on the ascription of beliefs and inference rules by the agents to each other. We present a formal model of a system of bounded reasoners which reason about each other's be- liefs, and investigate the problem of belief ascription in a resource-bounded setting. We show that for agents whose computational resources and memory are bounded, correct ascription of beliefs cannot be guaranteed, even in the limit. We propose a solution to the problem of correct belief ascription for feasible agents which involves ascribing reasoning strategies, or preferences on formulas, to other agents, and show that if a resource-bounded agent knows the reasoning strategy of another agent, then its ascription of beliefs to the other agent is correct in the limit.
    Synthese 01/2010; 173:179-197. · 0.70 Impact Factor
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    ABSTRACT: We describe a framework for the automated verification of multi-agent systems which do distributed problem solving, e.g., query answering. Each rea- soner uses facts, messages and Horn clause rules to derive new information. We show how to verify correctness of distributed problem solving under resource constraints, such as the time required to answer queries and the number of mes- sages exchanged by the agents. The framework allows the use of abstract spec- ifications consisting of Linear Time Temporal Logic (LTL) formulas to specify some of the agents in the system. We illustrate the use of the framework on a simple example.
    Model Checking and Artificial Intelligence - 6th International Workshop, MoChArt 2010, Atlanta, GA, USA, July 11, 2010, Revised Selected and Invited Papers; 01/2010
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    ABSTRACT: Many problems in AI and multi-agent systems research are most naturally formulated in terms of the abilities of a coalition of agents. There exist several excellent logical tools for reasoning about coali- tional ability. However, coalitional ability can be affected by the availability of resources, and there is no straightforward way of reasoning about resource requirements in logics such as Coalition Logic (CL) and Alternating-time Temporal Logic (ATL). In this paper, we propose a logic for reasoning about coalitional ability under resource constraints. We extend ATL with costs of actions and hence of strategies. We give a complete and sound axiomatisa- tion of the resulting logic Resource-Bounded ATL (RB-ATL) and an efficient model-checking algorithm for it.
    9th International Conference on Autonomous Agents and Multiagent Systems (AAMAS 2010), Toronto, Canada, May 10-14, 2010, Volume 1-3; 01/2010
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    Konstantin Vikhorev, Natasha Alechina, Brian Logan
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    ABSTRACT: We present a new approach to providing soft real- time guarantees for Belief-Desire-Intention (BDI) agents. We define what it means for BDI agents to operate in real time, or to satisfy real-time guarantees. We then develop a model of real-time performance which takes into account the time by which a task should be performed and the relative priority of tasks, and identify the key stages in a BDI architecture which must be bounded for real-time performance. As an illustration of our approach we introduce a new BDI architecture, ARTS, which allows the development of agents that guarantee (soft) real-time performance. ARTS extends ideas from PRS and JAM to include goals and plans which have deadlines and priorities, and schedules intentions so as to achieve the largest number of high priority intentions by their deadlines. Index Terms—BDI Agents, Real-time guarantees, Task Scheduling, Priority, Deadline, ARTS.
    Languages, Methodologies, and Development Tools for Multi-Agent Systems, Second International Workshop, LADS 2009, Torino, Italy, September 7-9, 2009, Revised Selected Papers; 01/2009

Publication Stats

500 Citations
7.70 Total Impact Points

Institutions

  • 2001–2013
    • University of Nottingham
      • School of Computer Science
      Nottigham, England, United Kingdom
  • 2006–2008
    • University Pompeu Fabra
      Barcino, Catalonia, Spain
    • University of Birmingham
      • School of Computer Science
      Birmingham, ENG, United Kingdom
  • 1994–1998
    • University of Amsterdam
      • Department of Computer Science
      Amsterdamo, North Holland, Netherlands