34 research outputs found
A Formal Context Representation Framework for Network-Enabled Cognition
Network-accessible resources are inherently contextual with respect to the specific situations (e.g., location and default assumptions) in which they are used. Therefore, the explicit conceptualization and representation of contexts is required to address a number of problems in Network- Enabled Cognition (NEC). We propose a context representation framework to address the computational specification of contexts. Our focus is on developing a formal model of context for the unambiguous and effective delivery of data and knowledge, in particular, for enabling forms of automated inference that address contextual differences between agents in a distributed network environment. We identify several components for the conceptualization of contexts within the context representation framework. These include jurisdictions (which can be used to interpret contextual data), semantic assumptions (which highlight the meaning of data), provenance information and inter-context relationships. Finally, we demonstrate the application of the context representation framework in a collaborative military coalition planning scenario. We show how the framework can be used to support the representation of plan-relevant contextual information
Bounded Rationality for Data Reasoning based on Formal Concept Analysis
Formal Concept Analysis (FCA) is a theory whose goal is to discover and extract Knowledge from qualitative data. It also provides tools for sound reasoning (implication basis and association rules). The aim of this paper is to apply FCA to a new model for bounded rationality based on the implicational reasoning over contextual knowledge bases which are obtained from contextual selections. A contextual selection is a selection of events and attributes about them which induces partial contexts from a global formal context. In order to avoid inconsistencies, association rules are selected as reasoning engine. The model is applied to forecast sport results.Ministerio de Ciencia e Innovación TIN2009-09492Junta de Andalucía TIC-606
LeoPARD --- A Generic Platform for the Implementation of Higher-Order Reasoners
LeoPARD supports the implementation of knowledge representation and reasoning
tools for higher-order logic(s). It combines a sophisticated data structure
layer (polymorphically typed {\lambda}-calculus with nameless spine notation,
explicit substitutions, and perfect term sharing) with an ambitious multi-agent
blackboard architecture (supporting prover parallelism at the term, clause, and
search level). Further features of LeoPARD include a parser for all TPTP
dialects, a command line interpreter, and generic means for the integration of
external reasoners.Comment: 6 pages, to appear in the proceedings of CICM'2015 conferenc
First-Order Logic for Flow-Limited Authorization
We present the Flow-Limited Authorization First-Order Logic (FLAFOL), a logic
for reasoning about authorization decisions in the presence of information-flow
policies. We formalize the FLAFOL proof system, characterize its
proof-theoretic properties, and develop its security guarantees. In particular,
FLAFOL is the first logic to provide a non-interference guarantee while
supporting all connectives of first-order logic. Furthermore, this guarantee is
the first to combine the notions of non-interference from both authorization
logic and information-flow systems. All theorems in this paper are proven in
Coq.Comment: Coq code can be found at https://github.com/FLAFOL/flafol-co
Temporal Annotations for a Contextual Logic Programming Language}
In this paper we propose the combination of modularity and temporal reasoning using logic programming as common ground. Moreover, we consider that the usage of a given module is influenced by temporal constraints, i.e. modularity and temporal reasoning are strongly connected. Besides illustrative examples, we also present the operational semantics and corresponding compiler for this language
Temporal reasoning in a logic programming language with modularity
Actualmente os Sistemas de Informação Organizacionais (SIO) lidam cada vez mais com informação que tem dependências temporais. Neste trabalho concebemos um ambiente de trabalho para construir e manter SIO Temporais. Este ambiente assenta sobre um linguagem lógica denominada Temporal Contextua) Logic Programming que integra modularidade com raciocínio temporal fazendo com que a utilização de um módulo dependa do tempo do contexto. Esta linguagem é a evolução de uma outra, também introduzida nesta tese, que combina Contextua) Logic Programming com Temporal Annotated Constraint Logic Programming, na qual a modularidade e o tempo são características ortogonais. Ambas as linguagens são formalmente discutidas e exemplificadas.
As principais contribuições do trabalho descrito nesta tese incluem:
• Optimização de Contextua) Logic Programming (CxLP) através de interpretação abstracta.
• Sintaxe e semântica operacional para uma linguagem que combina de um modo independente as linguagens Temporal Annotated Constraint Logic Programming (TACLP) e CxLP. É apresentado um compilador para esta linguagem.
• Linguagem (sintaxe e semântica) que integra de um modo inovador modularidade (CxLP) com raciocínio temporal (TACLP). Nesta linguagem a utilização de um dado módulo está dependente do tempo do contexto. É descrito um interpretador e um compilador para esta linguagem.
• Ambiente de trabalho para construir e fazer a manutenção de SIO Temporais. Assenta sobre uma especificação revista da linguagem ISCO, adicionando classes e manipulação de dados temporais. É fornecido um compilador em que a linguagem resultante é a descrita no item anterior. ABSTRACT- Current Organisational Information Systems (OIS) deal with more and more Infor-mation that, is time dependent. In this work we provide a framework to construct and maintain Temporal OIS. This framework builds upon a logical language called Temporal Contextual. Logic Programming that deeply integrates modularity with tem-poral reasoning making the usage of a module time dependent. This language is an evolution of another one, also introduced in this thesis, that combines Contextual Logic Programming with Temporal Annotated Constraint Logic Programming where modularity and time are orthogonal features. Both languages are formally discussed and illustrated.
The main contributions of the work described in this thesis include:
• Optimisation of Contextual Logic Programming (CxLP) through abstract interpretation.
• Syntax and operational semantics for an independent combination of the temporal framework Temporal Annotated Constraint Logic Programming (TACLP) and CxLP. A compiler for this language is also provided.
• Language (syntax and semantics) that integrates in a innovative way modularity
(CxLP) with temporal reasoning (TACLP). In this language the usage of a given
module depends of the time of the context. An interpreter and a compiler for
this language are described.
• Framework to construct and maintain Temporal Organisational Information Systems. It builds upon a revised specification of the language ISCO, adding temporal classes and temporal data manipulation. A compiler targeting the language presented in the previous item is also given
Integrating Temporal Annotations in a Modular Logic Language
Albeit temporal reasoning and modularity are very prolific fields of research in Logic Programming (LP) we find few examples of their integration. Moreover, in those examples, time and modularity are considered orthogonal to each other. In this paper we propose the addition of temporal annotations to a modular extension of LP such that the usage of a module is influenced by temporal conditions. Besides illustrative examples we also provide an operational semantics together with a compiler, allowing this way for the development of applications based on such language
A Probabilistic Framework for Information Modelling and Retrieval Based on User Annotations on Digital Objects
Annotations are a means to make critical remarks, to explain and
comment things, to add notes and give opinions, and to relate objects.
Nowadays, they can be found in digital libraries and collaboratories,
for example as a building block for scientific discussion on the one
hand or as private notes on the other. We further find them in product
reviews, scientific databases and many "Web 2.0" applications; even
well-established concepts like emails can be regarded as annotations
in a certain sense. Digital annotations can be (textual) comments,
markings (i.e. highlighted parts) and references to other documents
or document parts. Since annotations convey information which is
potentially important to satisfy a user's information need, this
thesis tries to answer the question of how to exploit annotations for
information retrieval. It gives a first answer to the question if
retrieval effectiveness can be improved with annotations.
A survey of the "annotation universe" reveals some facets of
annotations; for example, they can be content level annotations
(extending the content of the annotation object) or meta level ones
(saying something about the annotated object). Besides the annotations
themselves, other objects created during the process of annotation can
be interesting for retrieval, these being the annotated fragments.
These objects are integrated into an object-oriented model comprising
digital objects such as structured documents and annotations as well
as fragments. In this model, the different relationships among the
various objects are reflected. From this model, the basic data
structure for annotation-based retrieval, the structured annotation
hypertext, is derived.
In order to thoroughly exploit the information contained in structured
annotation hypertexts, a probabilistic, object-oriented logical
framework called POLAR is introduced. In POLAR, structured annotation
hypertexts can be modelled by means of probabilistic propositions and
four-valued logics. POLAR allows for specifying several relationships
among annotations and annotated (sub)parts or fragments. Queries can
be posed to extract the knowledge contained in structured annotation
hypertexts. POLAR supports annotation-based retrieval, i.e. document
and discussion search, by applying an augmentation strategy (knowledge
augmentation, propagating propositions from subcontexts like annotations,
or relevance augmentation, where retrieval status values are propagated)
in conjunction with probabilistic inference, where P(d -> q), the probability
that a document d implies a query q, is estimated.
POLAR's semantics is based on possible worlds and accessibility
relations. It is implemented on top of four-valued probabilistic Datalog.
POLAR's core retrieval functionality, knowledge augmentation with
probabilistic inference, is evaluated for discussion and document
search. The experiments show that all relevant POLAR objects, merged
annotation targets, fragments and content annotations, are able to
increase retrieval effectiveness when used as a context for discussion
or document search. Additional experiments reveal that we can determine
the polarity of annotations with an accuracy of around 80%