6841430
Mutual Enrichment for Agents Through Nested Belief Change: A Semantic Approach
This paper focuses on the dynamics of nested beliefs in the context of agent interactions. Nested beliefs represent what agents believe about the beliefs of other agents. We consider the tell KQML performative [1] which allows agents to send their own beliefs to others. Whenever agents accept a new belief, or refuse to change their own beliefs after receiving a message, both receiver and sender enrich their nested beliefs by refining their beliefs about (i) the other agent’s beliefs and (ii) the preferences of the other agent. The main objective of nested beliefs is to improve cooperation between agents. We propose a logical formalisation of the acquisition process of nested beliefs and preferences. This acquisition process is the first step towards the elaboration of sophisticated interaction protocols.
15894793
Implementing Iterated Belief Change Via Prime Implicates
Belief change is concerned with modelling the way in which an idealised (rational) reasoner maintains their beliefs and the way in which those beliefs are modified as the reasoner acquires new information. The AGM [1,3,5] framework is the most widely cited belief change methodology in the literature. It models the reasoner’s belief state as a set of sentences that is logically closed under deduction and provides for three belief change operations: expansion, contraction and revision. Each of the AGM belief change operations is motivated by principles of rationality that are formalised by way of rationality postulates.
10175705
Next Steps in Propositional Horn Contraction
Standard belief contraction assumes an underlying logic containing full classical propositional logic, but there are good reasons for considering contraction in less expressive logics. In this paper we focus on Horn logic. In addition to being of interest in its own right, our choice is motivated by the use of Horn logic in several areas, including ontology reasoning in description logics. We consider three versions of contraction: entailment-based and inconsistency-based contraction (e-contraction and i-contraction, resp.), introduced by Delgrande for Horn logic, and package contraction (p-contraction), studied by Fuhrmann and Hansson for the classical case. We show that the standard basic form of contraction, partial meet, is too strong in the Horn case. We define more appropriate notions of basic contraction for all three types above, and provide associated representation results in terms of postulates. Our results stand in contrast to Delgrande's conjectures that orderly maxichoice is the appropriate contraction for both e- and i-contraction. Our interest in p-contraction stems from its relationship with an important reasoning task in ontological reasoning: repairing the subsumption hierarchy in EL. This is closely related to p-contraction with sets of basic Horn clauses (Horn clauses of the form p → q). We show that this restricted version of p-contraction can also be represented as i-contraction.
1029481
Modelling Object Typicality in Description Logics
We present a semantic model of typicality of concept members in description logics (DLs) that accords well with a binary, globalist cognitive model of class membership and typicality. We define a general preferential semantic framework for reasoning with object typicality in DLs. We propose the use of feature vectors to rank concept members according to their defining and characteristic features, which provides a modelling mechanism to specify typicality in composite concepts.
1613464
Merging Epistemic States
Intelligent agents are often faced with the problem of trying to merge possibly conflicting pieces of information obtained from different sources into a consistent view of the world. We propose a framework for the modelling of such merging operations with roots in the work of Spohn [14]. Unlike most approaches we focus on the merging of epistemic states, not knowledge bases. We construct a number of plausible merging operations and measure them against various properties that merging operations ought to satisfy. Finally, we discuss the connection between merging and the use of infobases [9], [10].
1871739
Sydney OWL Syntax - towards a Controlled Natural Language Syntax for OWL 1.1
This paper describes a proposed new syntax that can be used to write and read OWL ontologies in Controlled Natural Language (CNL): a well-defined subset of the English language. Following the lead of Manchester OWL Syntax in making OWL more accessible for non-logicians, and building on the previous success of Schwitter’s PENG (Processable English), the proposed Sydney OWL Syntax enables two-way translation and generation of grammatically correct full English sentences to and from OWL 1.1 functional syntax. Used in conjunction with OWL tools, it is designed to facilitate ontology construction and editing by enabling authors to write an OWL ontology in a defined subset of English. It also improves readability and understanding of OWL statements or whole ontologies, by enabling them to be read as English sentences. It is hoped that by providing the option of an intuitive, easy to use English syntax which requires no specialized knowledge, the broader community will be far more likely to develop and benefit from Semantic Web applications. This paper is a discussion paper covering the scope, design, and examples of Sydney OWL Syntax in use, and the authors invite feedback on all aspects of the proposal via email to krr.sydneysyntax@cse.unsw.edu.au. Working drafts of the full specification are available at http://www.ics.mq.edu.au/~rolfs/sos.
3125532
Structure-based design of potent CDK1 inhibitors derived from olomoucine
Cyclin-dependent kinase 1 (CDK1), an enzyme participating in the regulation of the cell cycle, constitutes a possible target in the search for new antitumor agents. Starting from the purine derivative olomoucine and following a structure-based approach, potent inhibitors of this enzyme were rapidly identified. The molecular modeling aspects of this work are described.
16322351
On algorithmically checking whether a Hilbert series comes from a complete intersection
It is not possible to determine from the Hilbert series whether a commutative Z-graded Noetherian algebra is a complete intersection. Nevertheless, the Hilbert series of a complete intersection satisfies very stringent conditions and we define a concept CI-type for formal power series, that embodies some of these necessary properties. This definition becomes interesting mainly for algebras that are not standard i.e. not generated in degree 1. For the class of formal power series that occur as the Hilbert series of Z-graded Noetherian Cohen-Macaulay algebras, the main result is a criterion for a series to be of CI-type, that is formulated in terms of properties of truncated power series. Hence it can be used as the basis for an algorithm that provides in a finite number of steps either a rational function expression of the formal power series, or the information that the truncated power series is not of CI-type. Also sample computations using this algorithm on some non-standard graded invariant algebras are described.
18488287
A Self-Healing Multipath Routing Protocol
This paper introduces a self-healing multipath routing solution that is resilient to code knock-out attacks i.e., the software copes with changing network topologies and perturbations of link characteristics as well as loss of parts of its code base. We use the Fraglets artificial chemistry for building a distributed reaction network that spans the whole network topology. Unlike the use of explicit metric values in today's network protocols, our approach relies on the concentration of routing table entries to stochastically decide which path a packet should take through the network. A reinforcement mechanism rewards successful forwarding rules that compete against each other for delivering data packets over alternative paths. Our self-healing solution is based on the systematic use of self-replicating code that constantly rewrites itself.
13787606
Identification of cylin-dependent kinase 1 inhibitors of a new chemical type by structure-based design and database searching
We have selected cyclin-dependent kinase 1 (CDK1), an enzyme participating in the regulation of the cell cycle, as a target in our efforts to discover new antitumor agents. By exploiting available structural information, we designed an ATP-site directed ligand scaffold that allowed us to identify 4-(3-methyl-1,4-dioxo-1,4-dihydro-naphthalen-2-ylamino)-benzenesulfonamide as a new potent inhibitor of CDK1 in a subsequent database search. The synthesis and testing of some analogues confirmed the interest of this class of compounds as novel CDK1 inhibitors.
25161687
TAS and IsaWin: Generic Interfaces for Transformational Program Development and Theorem Proving
We present a new approach to the implementation of graphical user interfaces (GUIs) for formal program development systems like transformation systems or interactive theorem provers. Its distinguishing feature is a generic, open system design which allows the development of a family of tools for different formal methods on a sound logical basis with a uniform appearance. The context of this work is the UniForM project [KPO+95], the aim of which is to develop a framework integrating different formal methods in a logically consistent way. Consistency is achieved by encoding formal methods such as CSP and Z in the theorem prover Isabelle [Pau94], which is used to perform the program development as well as to prove the correctness of the transformation rules. One of the main UniForM objectives is to enable non-expert users to actually perform at least part of the developmen~ themselves. Hence there is a crucial need for an encapsulation technique of these Isabelle encodings providing a generic way of building graphical user interfaces.