28 research outputs found
A Complete Classification of Tractability in RCC-5
We investigate the computational properties of the spatial algebra RCC-5
which is a restricted version of the RCC framework for spatial reasoning. The
satisfiability problem for RCC-5 is known to be NP-complete but not much is
known about its approximately four billion subclasses. We provide a complete
classification of satisfiability for all these subclasses into polynomial and
NP-complete respectively. In the process, we identify all maximal tractable
subalgebras which are four in total.Comment: See http://www.jair.org/ for an online appendix and other files
accompanying this articl
Using a Temporal Constraint Network for Business Process Execution
Business process management (BPM) has emerged as a dominant technology in current enterprise systems and business solutions. However, the technology continues to face challenges in coping with dynamic business environments where requirements and goals are constantly changing. In this paper, we present a modelling framework for business processes that is conducive to dynamic change and the need for flexibility in execution. This framework is based on the notion of process constraints. Process constraints may be specified for any aspect of the process, such as task selection, control flow, resource allocation, etc. Our focus in this paper is on a set of scheduling constraints that are specified through a temporal constraint network. We will demonstrate how this specification can lead to increased flexibility in process execution, while maintaining a desired level of control. A key feature and strength of the approach is to use the power of constraints, while still preserving the intuition and visual appeal of graphical languages for process modelling
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Working notes of the 1991 spring symposium on constraint-based reasoning
Concept logics
Concept languages (as used in BACK, KL-ONE, KRYPTON, LOOM) are employed as knowledge representation formalisms in Artificial Intelligence. Their main purpose is to represent the generic concepts and the taxonomical hierarchies of the domain to be modeled. This paper addresses the combination of the fast taxonomical reasoning algorithms (e.g. subsumption, the classifier etc.) that come with these languages and reasoning in first order predicate logic. The interface between these two different modes of reasoning is accomplished by a new rule of inference, called constrained resolution. Correctness, completeness as well as the decidability of the constraints (in a restricted constraint language) are shown
A knowledge server for reasoning about temporal constraints between classes and instances of events
An outstanding example of early Reformation dress, notice the geometric fabric design, the fur-trimmed collar of the coat, and the decorative shir
Analysing the familiar : reasoning about space and time in the everyday world
The development of suitable explicit representations of knowledge that
can be manipulated by general purpose inference mechanisms has always
been central to Artificial Intelligence (AI). However, there has been a
distinct lack of rigorous formalisms in the literature that can be used
to model domain knowledge associated with the everyday physical world.
If AI is to succeed in building automata that can function reasonably
well in unstructured physical domains, the development and utility of such
formalisms must be secured.
This thesis describes a first order axiomatic theory that can be used
to encode much topological and metrical information that arises in our
everyday dealings with the physical world. The formalism is notable for
the minimal assumptions required in order to lift up a very general
framework that can cover the representation of much intuitive spatial and
temporal knowledge. The basic ontology assumes regions that can be
either spatial or temporal and over which a set of relations and
functions are defined. The resulting partitioning of these abstract
spaces, allow complex relationships between objects and the description of
processes to be formally represented. This also provides a useful
foundation to control the proliferation of inference commonly associated
with mechanised logics. Empirical information extracted from the domain
is added and mapped to these basic structures showing how further
control of inference can be secured.
The representational power of the formalism and computational
tractability of the general methodology proposed is substantiated using
two non-trivial domain problems - modelling phagocytosis and exocytosis
of uni-cellular organisms, and modelling processes arising during the
cycle of operations of a force pump