4,134 research outputs found
S+Net: extending functional coordination with extra-functional semantics
This technical report introduces S+Net, a compositional coordination language
for streaming networks with extra-functional semantics. Compositionality
simplifies the specification of complex parallel and distributed applications;
extra-functional semantics allow the application designer to reason about and
control resource usage, performance and fault handling. The key feature of
S+Net is that functional and extra-functional semantics are defined
orthogonally from each other. S+Net can be seen as a simultaneous
simplification and extension of the existing coordination language S-Net, that
gives control of extra-functional behavior to the S-Net programmer. S+Net can
also be seen as a transitional research step between S-Net and AstraKahn,
another coordination language currently being designed at the University of
Hertfordshire. In contrast with AstraKahn which constitutes a re-design from
the ground up, S+Net preserves the basic operational semantics of S-Net and
thus provides an incremental introduction of extra-functional control in an
existing language.Comment: 34 pages, 11 figures, 3 table
Temporal Data Modeling and Reasoning for Information Systems
Temporal knowledge representation and reasoning is a major research field in Artificial
Intelligence, in Database Systems, and in Web and Semantic Web research. The ability to
model and process time and calendar data is essential for many applications like appointment
scheduling, planning, Web services, temporal and active database systems, adaptive
Web applications, and mobile computing applications. This article aims at three complementary
goals. First, to provide with a general background in temporal data modeling
and reasoning approaches. Second, to serve as an orientation guide for further specific
reading. Third, to point to new application fields and research perspectives on temporal
knowledge representation and reasoning in the Web and Semantic Web
TEMPOS: A Platform for Developing Temporal Applications on Top of Object DBMS
This paper presents TEMPOS: a set of models and languages supporting the manipulation of temporal data on top of object DBMS. The proposed models exploit object-oriented technology to meet some important, yet traditionally neglected design criteria related to legacy code migration and representation independence. Two complementary ways for accessing temporal data are offered: a query language and a visual browser. The query language, namely TempOQL, is an extension of OQL supporting the manipulation of histories regardless of their representations, through fully composable functional operators. The visual browser offers operators that facilitate several time-related interactive navigation tasks, such as studying a snapshot of a collection of objects at a given instant, or detecting and examining changes within temporal attributes and relationships. TEMPOS models and languages have been formalized both at the syntactical and the semantical level and have been implemented on top of an object DBMS. The suitability of the proposals with regard to applications' requirements has been validated through concrete case studies
Topological Foundations of Cognitive Science
A collection of papers presented at the First International Summer Institute in Cognitive Science, University at Buffalo, July 1994, including the following papers:
** Topological Foundations of Cognitive Science, Barry Smith
** The Bounds of Axiomatisation, Graham White
** Rethinking Boundaries, Wojciech Zelaniec
** Sheaf Mereology and Space Cognition, Jean Petitot
** A Mereotopological Definition of 'Point', Carola Eschenbach
** Discreteness, Finiteness, and the Structure of Topological Spaces, Christopher Habel
** Mass Reference and the Geometry of Solids, Almerindo E. Ojeda
** Defining a 'Doughnut' Made Difficult, N .M. Gotts
** A Theory of Spatial Regions with Indeterminate Boundaries, A.G. Cohn and N.M. Gotts
** Mereotopological Construction of Time from Events, Fabio Pianesi and Achille C. Varzi
** Computational Mereology: A Study of Part-of Relations for Multi-media Indexing, Wlodek Zadrozny and Michelle Ki
Towards an Adaptive Skeleton Framework for Performance Portability
The proliferation of widely available, but very different, parallel architectures
makes the ability to deliver good parallel performance
on a range of architectures, or performance portability, highly desirable.
Irregularly-parallel problems, where the number and size
of tasks is unpredictable, are particularly challenging and require
dynamic coordination.
The paper outlines a novel approach to delivering portable parallel
performance for irregularly parallel programs. The approach
combines declarative parallelism with JIT technology, dynamic
scheduling, and dynamic transformation.
We present the design of an adaptive skeleton library, with a task
graph implementation, JIT trace costing, and adaptive transformations.
We outline the architecture of the protoype adaptive skeleton
execution framework in Pycket, describing tasks, serialisation,
and the current scheduler.We report a preliminary evaluation of the
prototype framework using 4 micro-benchmarks and a small case
study on two NUMA servers (24 and 96 cores) and a small cluster
(17 hosts, 272 cores). Key results include Pycket delivering good
sequential performance e.g. almost as fast as C for some benchmarks;
good absolute speedups on all architectures (up to 120 on
128 cores for sumEuler); and that the adaptive transformations do
improve performance
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