Sensor networks are notoriously difficult to program, given that they encompass the complexities of both distributed and embedded systems. To address this problem, we present the design and implementation of a declara...
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ISBN:
(纸本)9781595937636
Sensor networks are notoriously difficult to program, given that they encompass the complexities of both distributed and embedded systems. To address this problem, we present the design and implementation of a declarative sensor network platform, DSN: a declarative language, compiler and runtime suitable for programming a broad range of sensornet applications. We demonstrate that our approach is a natural fit for sensor networks by specifying several very different classes of traditional sensor network protocols. services and applications entirely declaratively - these include tree and geographic routing, link estimation, data collection, event tracking, version coherency, and localization. To our knowledge, this is the first time these disparate sensornet tasks have been addressed by a single high-level programming environment. Moreover, the declarative approach accommodates the desire for architectural flexibility and simple management of limited resources. Our results suggest that the declarative approach is well-suited to sensor networks, and that it can produce concise and flexible code by focusing on what the code is doing, and not on how it is doing it.
Database systems are more and more employed to analyze an ever increasing amount of temporal data by applying a continuously evolving knowledge and are expected to do this in a timely fashion. Examples are financial s...
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ISBN:
(纸本)9783319105178
Database systems are more and more employed to analyze an ever increasing amount of temporal data by applying a continuously evolving knowledge and are expected to do this in a timely fashion. Examples are financial services, computer systems monitoring, air traffic monitoring, and patient care. In each of these cases data are processed in order to understand current situations and to determine optimal responses. In this paper, we exemplarily investigate system requirements for a patient care scenario in which patient data are continuously collected and processed by a database system. We show that the concepts provided by today's systems are still not enough for supporting the complex reasoning process needed. In particular, we identify situation-based reasoning as a missing database component and propose a temporal state concept for leveraging simple event processing. States provide a high level (and qualitative) description of past and current situations defined over streams of medical data, complemented by projections into the future. Our proposed database extension allows for a compact and intuitive representation of medical data;much like physicians use abstraction from details and dramatically simplifies the analysis of medical data.
Graphs are a way to describe complex entities and their relations that apply to many practically relevant domains. However, domains often differ not only in the properties of nodes and edges, but also in the constrain...
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ISBN:
(纸本)9798400701191
Graphs are a way to describe complex entities and their relations that apply to many practically relevant domains. However, domains often differ not only in the properties of nodes and edges, but also in the constraints imposed to the overall structure. This makes hard to define a general representation and genetic operators for graphs that permit the evolutionary optimization over many domains. In this paper, we tackle this challenge. We first propose a representation template that can be customized by users for specific domains: the constraints and the genetic operators are given in Prolog, a declarative programming language for operating with logic. Then, we define an adaptive evolutionary algorithm that can work with a large number of genetic operators by modifying their usage probability during the evolution: in this way, we relieve the user from the burden of selecting in advance only operators that are "good enough". We experimentally evaluate our proposal on two radically different domains to demonstrate its applicability and effectiveness: symbolic regression with trees and text extraction with finite-state automata. The results are promising: our approach does not trade effectiveness for versatility and is not worse than other domain-tailored approaches.
We propose CLP(QS), a declarative spatial reasoning framework capable of representing and reasoning about high-level, qualitative spatial knowledge about the world. We systematically formalize and implement the semant...
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ISBN:
(纸本)9783642231957
We propose CLP(QS), a declarative spatial reasoning framework capable of representing and reasoning about high-level, qualitative spatial knowledge about the world. We systematically formalize and implement the semantics of a range of qualitative spatial calculi using a system of non-linear polynomial equations in the context of a classical constraint logic programming framework. Whereas CLP(QS) is a general framework, we demonstrate its applicability for the domain of Computer Aided Architecture Design. With CLP(QS) serving as a prototype, we position declarative spatial reasoning as a general paradigm open to other formalizations, reinterpretations, and extensions. We argue that the accessibility of qualitative spatial representation and reasoning mechanisms via the medium of high-level, logic-based formalizations is crucial for their utility toward solving real-world problems.
Temporally constrained matching in a persistent and declarative object-oriented system is introduced as a semantic alternative to the existing approaches to the covariance/contravariance problem. While the existing ob...
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ISBN:
(纸本)3540648232
Temporally constrained matching in a persistent and declarative object-oriented system is introduced as a semantic alternative to the existing approaches to the covariance/contravariance problem. While the existing object-oriented type systems are based on subtyping, F-bounded polymorphism and matching, this language system is based entirely on inheritance, which is identified with matching, The type of matching used in this paper relies on the temporal constraint system. We prove that this constrained matching guarantees type safe substitutability even in situations where matching alone would not. This is possible only because the underlying formal system is semantically much richer than the paradigms of type systems. Its temporal constraint system can capture subtleties that go far beyond the level of expressiveness of object-oriented type systems. The temporal nature of the language and its distinctive orthogonal model of persistence make this language system successful in handling a variety of non-trivial applications.
Thanks to the high expressive power and the rule-based nature of declarative languages, their influences are growing in the fields of AI, knowledge representation, and so on. On the other hand, since the notion of &qu...
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ISBN:
(纸本)9783642140549
Thanks to the high expressive power and the rule-based nature of declarative languages, their influences are growing in the fields of AI, knowledge representation, and so on. On the other hand, since the notion of "equality" plays a crucial role on such languages, in this paper we focus in the design of a flexible (fuzzy) but efficient (lazy) notion of equality for hybrid declarative languages amalgamating functional-fuzzy-logic features. Here, we show that, by extending at a very low cost the notion of "strict equality" typically used in lazy functional-logic languages (Curry, Toy), and by relaxing it to the more flexible one of similar equality used in fuzzy-logic programming languages (Likelog, Bousi similar to Prolog), similarity relations can be successfully treated while mathematical functions are lazily evaluated in a given program. Our method represents a very easy, low-cost way, for fuzzifying lazy functional-logic languages and it can be implemented at a very high abstraction level by simply performing a static pre-process at compilation time which only manipulates the program at a syntactic level (i.e., the underlying operational mechanism based on rewriting/narrowing remains untouched).
Set-grouping and aggregation are powerful non-monotonic operations of practical interest in database query languages. We consider the problem of expressing aggregation via negation as failure (NF). We study this probl...
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ISBN:
(纸本)3540628436
Set-grouping and aggregation are powerful non-monotonic operations of practical interest in database query languages. We consider the problem of expressing aggregation via negation as failure (NF). We study this problem in the framework of partial-order clauses introduced in [JOM95]. We show a translation of partial-order programs to normal programs that is very natural: Any cost-monotonic partial-order program P becomes a stratified normal program transl(P) such that the declarative semantics of P is equivalent to the stratified semantics of transl(P). The ability to effect such a translation is significant because the resulting normal programs do not make any explicit use of the aggregation capability, yet they are concise and intuitive. The success of this translation is due to the fact that the translated program is a stratified normal program. That would not be the case for other more general classes of programs than cost-monotonic partial-order programs. We therefore investigate a second land more natural) translation that does not require the translated programs to be stratified, but requires the use of a suitable NF strategy. The class of normal programs originating from this translation is itself interesting. Every program in this class has a clear intended total model, although these programs are in general not stratified and not even call-consistent and do not have a stable model. The partial model given by the well-founded semantics is consistent with the intended total model and the extended well founded semantics WFS+ indeed defines the intended model. Since there is a well-defined and efficient operational semantics for partial-order programs [JOM95, JM95] we conclude that the gap between expression of a problem and computing its solution can be reduced with the right level of notation.
We present the architecture and a performance assessment of an extensible query optimizer written in Venus. Venus is a general-purpose active-database rule language embedded in C++. Following the developments in exten...
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ISBN:
(纸本)1581131461
We present the architecture and a performance assessment of an extensible query optimizer written in Venus. Venus is a general-purpose active-database rule language embedded in C++. Following the developments in extensible database query optimizers, first in rule-based form, followed by optimizers written as object-oriented programs, the Venus-based optimizer avails to the advantages of both. Venus' modular structure allows us to go a step further and provide extensibility in search by defining parameterized search components in a declarative form that has the additional effect of integrating heuristic and cost-based optimization. We compare optimizers developed with Volcano, OPT++ and Venus. Venus' optimizing compiler yields code whose performance is comparable with Volcano and OPT++ on smaller queries. The ability to introduce additional pruning heuristics yields better scalability on larger queries. Evaluation of the system using quantitative software metrics supports a claim that the Venus-based optimizer is more easily maintained and extended than are its predecessors.
Over the past few years, multi-touch user interfaces emerged from research prototypes into mass market products. This evolution has been mainly driven by innovative devices such as Apple's iPhone or Microsoft'...
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ISBN:
(纸本)9781450306287
Over the past few years, multi-touch user interfaces emerged from research prototypes into mass market products. This evolution has been mainly driven by innovative devices such as Apple's iPhone or Microsoft's Surface tabletop computer. Unfortunately, there seems to be a lack of software engineering abstractions in existing multi-touch development frameworks. Many multi-touch applications are based on hard-coded procedural low level event processing. This leads to proprietary solutions with a lack of gesture extensibility and cross-application reusability. We present Midas, a declarative model for the definition and detection of multi-touch gestures where gestures are expressed via logical rules over a set of input facts. We highlight how our rule-based language approach leads to improvements in gesture extensibility and reusability. Last but not least, we introduce JMidas, an instantiation of Midas for the Java programming language and describe how JMidas has been applied to implement a number of innovative multi-touch gestures.
Building on a compositional relational programming language Combilog, code visualization with a motivation of flexible practical applications is explored. Following from earlier work, a new coloured and human percepti...
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ISBN:
(纸本)9781479903696
Building on a compositional relational programming language Combilog, code visualization with a motivation of flexible practical applications is explored. Following from earlier work, a new coloured and human perception-centric iteration of visual representation is introduced, and its effects on understanding code are analysed by means of a user study. Results showed that visuals helped participants to solve code-related questions 46% faster with 69% less errors.
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