Types Of Temporal Constraints Research Articles

Time-Based Web Service Composition

This article describes how incorporating temporal constraints in web service composition results in more complex models and makes the verification of temporal consistency during the modeling and execution crucial. This article proposes a model named H-Service-Net based on the time petri net model to control and manage temporal consistency; the model also supports time constraints and exception handling. First, this approach proposes a modular approach for modeling composition using Extend Time Unit System, Allen's interval algebra, and comparison operators in a time petri net model to consider all types of temporal constraints. Subsequently, this article presents algorithms on checking temporal consistency and mechanism for exception handling and validating the system in an implementation tool (H-Service-Editor) based on the proposed approach that uses BizTalk Server 2013 to evaluate the implementation of temporal constraints and timeout exception handling. Finally, an exhaustive performance experiment is presented to assess the scalability of the authors' approach.

Toward a comprehensive treatment of temporal constraints about periodic events

In this article, we propose an Allen-like approach to deal with different types of temporal constraints about periodic events. We consider the different components of such constraints (thus, unlike Allen, we also take into account quantitative constraints) including frame times, user-defined periods, qualitative temporal constraints, and numeric quantifiers and the interactions between such components. We propose a specialized high-level formalism to represent temporal constraints about periodic events; temporal reasoning on the formalism is performed by a path-consistency algorithm repeatedly applying our operations of inversion, intersection, and composition and by a specialized reasoner about periods and numeric quantification. The high-level formalism has been designed in such a way that different types of temporal constraints about periodic events can be represented in a compact and (hopefully) user-friendly way and path-consistency-based temporal reasoning on the formalism can be performed in polynomial time. We also prove that our definitions of inversion, intersection, and composition and, thus, of our path-consistency algorithm, are correct. This article also sketches the general architecture of the temporal manager for periodic events (TeMP+), that has been designed on the basis of our approach. As a working example, we show an application of our approach to scheduling in a school. © 2003 Wiley Periodicals, Inc.

Temporal Reasoning for a Collaborative Planning Agent in a Dynamic Environment

We present a temporal reasoning mechanism for an individual agent situated in a dynamic environment such as the web and collaborating with other agents while interleaving planning and acting. Building a collaborative agent that can flexibly achieve its goals in changing environments requires a blending of real-time computing and AI technologies. Therefore, our mechanism consists of an Artificial Intelligence (AI) planning subsystem and a Real-Time (RT) scheduling subsystem. The AI planning subsystem is based on a model for collaborative planning. The AI planning subsystem generates a partial order plan dynamically. During the planning it sends the RT scheduling subsystem basic actions and time constraints. The RT scheduling subsystem receives the dynamic basic actions set with associated temporal constraints and inserts these actions into the agent's schedule of activities in such a way that the resulting schedule is feasible and satisfies the temporal constraints. Our mechanism allows the agent to construct its individual schedule independently. The mechanism handles various types of temporal constraints arising from individual activities and its collaborators. In contrast to other works on scheduling in planning systems which are either not appropriate for uncertain and dynamic environments or cannot be expanded for use in multi-agent systems, our mechanism enables the individual agent to determine the time of its activities in uncertain situations and to easily integrate its activities with the activities of other agents. We have proved that under certain conditions temporal reasoning mechanism of the AI planning subsystem is sound and complete. We show the results of several experiments on the system. The results demonstrate that interleave planning and acting in our environment is crucial.

Toward a Unifying Ontology Dealing with Both User–Defined Periodicity and Temporal Constraints About Repeated Events

This article proposes a first–order logic axiomatic description of some basic ontological notions underlying the meaning of different types of temporal constraints about repeated events. The article also shows that such an ontology provides an homogeneous framework that can be used to model and compare the intended meaning of different formalisms in the artificial intelligence and temporal databases literature which deal with user–defined calendar dates and/or qualitative and quantitative constraints between different types of repeated events.

The multi-mode resource-constrained project scheduling problem with generalized precedence relations

In this paper, we tackle the challenging problem of scheduling activities to minimize the project duration, in which the activities (a) are subject to generalized precedence relations, (b) require units of multiple renewable, non-renewable and doubly constrained resources for which a limited availability is imposed, and (c) can be performed in one of several different ways, reflected in multiple activity scenarios or modes. These multiple modes give rise to several kinds of trade-offs (time/resource, time/cost and resource/resource trade-offs) which allow for a more efficient allocation and use of resources. We present a local search-based solution methodology which is able to handle many real-life project scheduling characteristics such as time-varying resource requirements and availabilities, activity ready times, due dates and deadlines, activity overlaps, activity start time constraints and other types of temporal constraints.