15831559
An agent-based Petri net model with application to seller/buyer design in electronic commerce
Agents are becoming one of the most important topics in distributed and autonomous decentralized systems (ADS), and there are increasing attempts to use agent technologies to develop software systems in electronic commerce. Such systems are complex and there is a pressing need for system modeling techniques to support reliable, maintainable and extensible design. G-Nets are a type of Petri net defined to support modeling of a system as a set of independent and loosely-coupled modules. The authors first introduce an extension of G-Net, agent based G-Net, as a generic model for agent design. Then new communication mechanisms are introduced to support asynchronous message passing among agents. To illustrate that our formal modeling technique is effective for agent modeling in electronic commerce, a price-negotiation protocol example between buyers and sellers is provided. Finally, by analyzing an ordinary Petri net reduced from our agent based G-Net models, we conclude that our agent based G-Net models are L3-live, concurrent and effective for agent communications.
5913002
Formal modeling of synchronization methods for concurrent objects in Ada 95
One important role for Ada programming is to aid engineering of concurrent and distributed software. In a concurrent and distributed environment, objects may execute concurrently and need to be synchronized to serve a common goal. Three basic methods by which objects in a concurrent environment can be constructed and synchronized have been identified [1]. To formalize the semantics of these methods and to provide a formal model of their core behavior, we provide some graphic models based on the Petri net formalism. The purpose of this formal modeling is to illustrate the possibility of automatic program analysis for object-oriented features in Ada-95. Models for the three distributed- object synchronization methods are discussed, and a potential deadlock situation for one of the methods/models is illustrated. We conclude with some comparison of the three methods in terms of the model abstractions.
9774737
A framework for modeling agent-oriented software
With the increasing importance of complex software systems in the software industry, the need for using agent technologies to develop large-scale commercial and industrial software systems is growing rapidly. Such systems are complex, and there is a pressing need for system modeling techniques to support reliable, maintainable and extensible design. G-nets are a type of Petri net defined to support the modeling of a system as a set of independent and loosely-coupled modules. In this paper, we first introduce an extension of G-nets - the agent-based G-net - as a generic model for agent design. Then, to progress from an agent-based design model to an agent-oriented model, new mechanisms to support inheritance modeling are introduced. To illustrate our formal modeling technique for multi-agent systems, an example of an agent family in electronic commerce is provided.
14915210
A Framework for Model-Based Design of Agent-Oriented Software
Agents are becoming one of the most important topics in distributed and autonomous decentralized systems, and there are increasing attempts to use agent technologies to develop large-scale commercial and industrial software systems. The complexity of such systems suggests a pressing need for system modeling techniques to support reliable, maintainable, and extensible design. G-nets are a type of Petri net defined to support system modeling in terms of a set of independent and loosely-coupled modules. In this paper, we customize the basic G-net model to define a so-called "agent-based G-net" that can serve as a generic model for agent design. Then, to progress from an agent-based design model to an agent-oriented model, new mechanisms to support inheritance modeling are introduced. To illustrate our formal modeling technique for multiagent systems, an example of an agent family in electronic commerce is provided. Finally, we demonstrate how we can use model checking to verify some key behavioral properties of our agent model. This is facilitated by the use of an existing Petri net tool.
205925700
Compositional Petri net models of advanced tasking in Ada-95
The Ada language has been designed to support development of concurrent and distributed software. While the Ada-83 standard defined the basic mechanisms of rendezvous-based tasking, the Ada-95 standard significantly extended this capability with the introduction of several advanced tasking constructs. We present and discuss formal models of these key tasking constructs using the Petri net model. We also provide some formal evaluation of the models using one particular net-based method, invariant analysis. The constructs considered are the asynchronous transfer of control, the protected object, and the requeue statement. By modeling these advanced Ada tasking constructs with Petri nets, we obtain compositional models of the constructs that are complementary to earlier work in net-based modeling of Ada tasking, both in terms of defining precise behavior for tasking semantics, and also in terms of providing support for automated analysis of concurrent software.
955272
A Formal Approach to Detecting Shilling Behaviors in Concurrent Online Auctions
Shilling behaviors are one of the most serious fraud problems in online auctions, which make winning bidders have to pay more than what they should pay for auctioned items. In concurrent online auctions, where multiple auctions for the same type of items are running simultaneously, shilling behaviors can be even more severe because detecting, predicting and preventing such fraudulent behaviors become very difficult. In this paper, we propose a formal approach to detecting shilling behaviors in concurrent online auctions using model checking techniques. We first develop a model template that represents two concurrent online auctions in Promela. Based on the model template, we derive an auction model that simulates the bidding processes of two concurrent auctions. Then we use the SPIN model checker to formally verify if the auction model satisfies any questionable behavioral properties that are written in LTL (Linear Temporal Logic) formulas. Thus, our approach simplifies the problem of searching for shilling behaviors in concurrent online auctions into a model checking problem. Finally, we provide a case study to illustrate how our approach can effectively detect possible shill bidders.
10887257
Foundations of SMS commerce success: lessons from SMS messaging and co-opetition
As a convenient and low-cost mobile communication technology, short messaging service (SMS) is experiencing very rapid growth. It is reported that 700 million mobile phone users worldwide sent 20 to 30 billion SMS messages every month in 2001. At the same time, SMS commerce applications have emerged to provide mobile users consumer-oriented services. The huge SMS messaging customer base serves as the potential SMS commerce customer base according to K. Kellett and A. Linde (2001) . However, the bloom in messaging business does not automatically lead to the success of general SMS commerce applications. In this paper, we analyzed SMS developments in three different countries to derive three success indicators for SMS messaging and relate them to the success of SMS commerce. Based on the proposed SMS application framework, we postulate four additional hypothesized success factors that could uniquely contribute to the success of SMS commerce. Our findings provide practical implications for promoting SMS commerce applications successfully.
9140729
INSPIRE: an interactive image assisted non-photorealistic rendering system
We present a GPU supported interactive non-photorealistic rendering system, INSPIRE, which performs feature extraction in both image space, on intermediately rendered images, and object space, on models of various representations, e.g., point, polygon, or hybrid models, without needing connectivity information. INSPIRE obtains interactive NPR rendering with most styles of existing NPR systems, but offers more flexibility on model representations and compromises little on rendering speed.
10142893
PointWorks: Abstraction and Rendering of Sparsely Scanned Outdoor Environments
This paper describes a system, dubbed PointWorks, for rendering three-dimensionally digitized outdoor environments in non-photorealistic rendering styles. The challenge in rendering scanned outdoor environments is accommodating their inaccuracy, incompleteness, and large size to deliver a smooth animation without suggesting the underlying data deficiency. The key method discussed in this paper is employing artistic drawing techniques to illustrate features of varying importance and accuracy. We employ a point-based representation of the scanned environment and operate directly on point-based models for abstraction and rendering. We develop a framework for producing mainly two artistic styles: painterly and profile lines. Strategies have also been employed to leverage modern graphics hardware for achieving interactive rendering of large scenes.
5903660
Stylized rendering of 3D scanned real world environments
This paper presents an interactive non-photorealistic rendering (NPR) system that stylizes and renders outdoor scenes captured by 3D laser scanning. In order to deal with the large size, complexity and inherent incompleteness of data obtained from outdoor scans, our system represents outdoor scenes using points instead of traditional polygons. Algorithms are then developed to extract, stylize and render features from this point representation. In addition to conveying various NPR styles, our system also promises consistency in animation by maintaining stroke coherence and density. We achieve NPR of large data at interactive rates by designing novel data structures and algorithms as well as leveraging new features of commodity graphics hardware.
16644843
Alleviating Consumers' Privacy Concerns in Location-Based Services: A Psychological Control Perspective
Location-based services (LBS), enabled by advances in mobile and positioning technologies, have afforded users with a pervasive flexibility to be uniquely addressable and to access network and services on-the-move. However, because LBS could also associate the lifestyle habits, behaviors, and movements with a consumer’s personal identity, privacy concerns are particularly salient for LBS. Drawing on psychological control and privacy literature, we designed an experiment study to test the basic proposition that the assurance of consumers’ perceived control over their personal information has a considerable influence on alleviating their privacy concerns. Three different mechanisms of assurance of control—technology, industry self-regulation, and legislation—were manipulated in the experiment, and their effects on consumers’ privacy concerns were examined. The results indicated that the technological assurance mechanism (i.e., mobile device in this study) played the most important role in assuring consumers’ perceived control over personal information. The marriage of the privacy and psychological control literature streams provides a rich understanding of consumers’ privacy reaction to LBS usage and, therefore, benefits the privacy and human-computer interaction (HCI) research in the Information Systems discipline.