AN ACL FOR SPECIFYING FAULT-TOLERANT PROTOCOLS

Agent communication languages (ACLs) should allow the developer to adopt human-like communication mechanisms in agent programming, facilitating the development of distributed protocols in multi-agent systems (MASs). However, to implement robust protocols, ACLs should provide a way to deal with the failures of agents, as MASs are prone to the same failures that can occur in any distributed software system. In this paper, we address this issue showing how an asynchronous ACL that provides high-level mechanisms to deal with crash failures of agents can be effectively used to specify fault tolerant protocols.     

一个新的分布式安全电子拍卖协议

基于Shamir的（t＋1,n）门限方案和公钥加及数字签名提出一个适于分布式松耦合发布／预约系统使用的安全电子拍卖协议。协议除满足了安全分布式拍卖的基本需求外,还保证了代理拍卖服务器的不可否认性及投标者的匿名性。与先前工作相比,新协议具有较多的安全特性,而且更适合于分布式大规模拍卖。松耦合发布预约结构广泛使用于可扩展 自适应的分布式系统中,它的灵活性使之为许多应用所采用。但是,在不安全的通信环境中,这种结构缺乏容错性和安全支持,新协议可以在分布式松耦合发布／预约系统中实现安全性和容错性,同时具有适当的运行效率。最后,我们对协议设计的正确性和效率进行了详尽分析。     

An object based algebra for specifying a fault tolerant software architecture

In this paper we present an algebra of actors extended with mechanisms to model crash failures and their detection. We show how this extended algebra of actors can be successfully used to specify distributed software architectures. The main components of a software architecture can be specified following an object-oriented style and then they can be composed using asynchronous message passing or more complex interaction patterns. This formal specification can be used to show that several requirements of a software system are satisfied at the architectural level despite failures. We illustrate this process by means of a case study: the specification of a software architecture for intelligent agents which supports a fault tolerant anonymous interaction protocol.     

Autonomous Adaptive Agents for Single Seller Sealed Bid Auctions

In developing open, heterogeneous and distributed multi-agent systems researchers often face a problem of facilitating negotiation and bargaining amongst agents. It is increasingly common to use auction mechanisms for negotiation in multi-agent systems. The choice of auction mechanism and the bidding strategy of an agent are of central importance to the success of the agent model. Our aim is to determine the best agent learning algorithm for bidding in a variety of single seller auction structures in both static environments where a known optimal strategy exists and in complex environments where the optimal strategy may be constantly changing. In this paper we present a model of single seller auctions and describe three adaptive agent algorithms to learn strategies through repeated competition. We experiment in a range of auction environments of increasing complexity to determine how well each agent performs, in relation to an optimal strategy in cases where one can be deduced, or in relation to each other in other cases. We find that, with a uniform value distribution, a purely reactive agent based on Cliff’s ZIP algorithm for continuous double auctions (CDA) performs well, although is outperformed in some cases by a memory based agent based on the Gjerstad Dickhaut agent for CDA.     

EFFECTS OF A RATIONING RULE ON THE AUSUBEL AUCTION: A GENETIC ALGORITHM IMPLEMENTATION

The increasing use of auctions as a selling mechanism has led to a growing interest in the subject. Thus both auction theory and experimental examinations of these theories are being developed. A recent method used for carrying out examinations on auctions has been the design of computational simulations. The aim of this article is to develop a genetic algorithm to find automatically a bidder optimal strategy while the other players are always bidding sincerely. To this end a specific dynamic multiunit auction has been selected: the Ausubel auction, with private values, dropout information, and with several rationing rules implemented. The method provides the bidding strategy (defined as the action to be taken under different auction conditions) that maximizes the bidder's payoff. The algorithm is tested under several experimental environments that differ in the elasticity of their demand curves, number of bidders and quantity of lots auctioned. The results suggest that the approach leads to strategies that outperform sincere bidding when rationing is needed.     

Decentralized Peer-to-Peer Auctions

This paper proposes a flexible architecture for the creation of Internet auctions. It allows the custom definition of the auction parameters, and provides a decentralized control of the auction process. Auction policies are defined as laws in the Law Governed Interaction (LGI) paradigm. Each of these laws specifies not only the auction algorithm itself (e.g., open-cry, Dutch, etc.) but also how to handle the other parameters usually involved in the online auctions, such as certification, auditioning, and treatment of complaints. LGI is used to enforce the rules established in the auction policy within the agents involved in the process. After the agents find out about the actions, they interact in a peer-to-peer communication protocol, reducing the role of the centralized auction room to an advertising registry, and taking profit of the distributed nature of the Internet to conduct the auction. The paper presents an example of an auction law, illustrating the use of the proposed architecture.     

Understanding auction fever: a framework for emotional bidding

Auction fever is a multifaceted phenomenon that is frequently observed in both traditional and Internet auctions. In order to gain a better understanding of its causes, we develop a conceptual framework to analyze emotions in auctions, which is based on an exhaustive literature review. The framework integrates rational calculus with emotional aspects and suggests that emotional processing is triggered at three different stages of an auction: First, the economic environment can affect a bidder’s level of perceived competition and thus influence the bidding strategy prior to the auction. Second, auction events may have ramifications on the bidder’s emotional state during the auction due to previous investments or perceived ownership. Third, past auction outcomes may impact future bidding behavior through emotions such as the joy of winning or loser regret. Auction fever, eventually, is a phenomenon that results from the interplay of these emotional processes and causes a bidder to deviate from an initially chosen bidding strategy.     

Automated Negotiation from Declarative Contract Descriptions

Our approach for automating the negotiation of business contracts proceeds in three broad steps. First, determine the structure of the negotiation process by applying general knowledge about auctions and domain–specific knowledge about the contract subject along with preferences from potential buyers and sellers. Second, translate the determined negotiation structure into an operational specification for an auction platform. Third, after the negotiation has completed, map the negotiation results to a final contract. We have implemented a prototype which supports these steps by employing a declarative specification (in courteous logic programs) of (1) high–level knowledge about alternative negotiation structures, (2) general–case rules about auction parameters, (3) rules to map the auction parameters to a specific auction platform, and (4) special–case rules for subject domains. We demonstrate the flexibility of this approach by automatically generating several alternative negotiation structures for the domain of travel shopping in a trading agent competition.     

拍卖方法引入多Agent系统

Auction, an operational and effective resource allocation method, generally results in economical efficiency allocation between buyers and sellers. As a negotiation method, auction can be used in Multi-Agent Systems. Withthe consideration of computation ability and communication ability of agents, superadditive and subadditive property of goods, requirements of agents' revenue and real-time ability, proper auction methods can be selected to achieveone-many or many-many task assignments or resource allocation. In this paper, we systematically summarize bidingrules, buyers and sellers' strategies and the performances of current auction methods. A formal auction model, whichfits most of the current auction methods, is also presented.     

An agent-based English auction protocol using Elliptic Curve Cryptosystem for mobile commerce

Rapid development of the Internet and the extensive use of mobile phones have increased demand for mobile devices in Internet auctions. This trend is acting as an incentive to develop an auction model for mobile-based environment. Recently, Kuo-Hsuan Huang proposed a mobile auction agent model (MoAAM), which allows the bidders to participate in online auctions through a mobile agent. He used modular exponentiation operations in his method. As a result, the processing time for key generation, bidding, and verification were long. Thus, we propose to add the concept of Elliptic Curve Cryptosystem (ECC) onto MoAAM, because ECC has low computation amount and small key size, both of which will aid to increase the speed in generating keys, bidding, and verification. In terms of reduction of computation load on mobile devices and auction-manager server, the proposed method will make online auction system more efficient as well as more convenient to use. This paper mainly uses the English auction protocol as the key auction protocol. The protocol consists of four entities: Registration Manager (RM), Agent House (AH), Auction House (AUH), and Bidders (B). The Registration Manager registers and verifies Bidder identity. The Agent House manages the agents and assigns public transaction keys to Bidders. The Auction House provides a place for auction and maintains all necessary operations for a smooth online auction. Bidders are buyers who are interested in purchasing items at the auction. Our proposed method conforms to the requirements of an online auction protocol in terms of anonymity, traceability, no framing, unforgetability, non-repudiation, fairness, public verifiability, unlinkability among various auction rounds, linkability within a single auction round, efficiency of bidding, one-time registration, and easy revocation.     

Supply web co-ordination by an agent-based trading network with integrated logistics services

B2B interactions, like electronic negotiations and auctions between suppliers and customers, could be significantly improved by enabling the participants to adapt their bidding strategies to current logistics information (e.g., about transportation condition, cost or dates) while the negotiation goes on. We present an approach of an agent-based information and trading network (ITN) called CASA for dynamic production and sales of timber; the integrated services for logistics and e-commerce are efficiently coordinated by appropriate types of holonic structured intelligent agents of the network. We introduce the agent-based architecture and describe how the agents build their plans and optimize them afterwards. For optimizing their plans, the agents use various market-based negotiation mechanisms, i.e., several auction mechanisms and the simulated trading mechanism described in detail in this article. The effects of the different mechanisms on resulting cost and surplus have been evaluated by various simulation runs in different competitive and co-operative settings. It turned out that the simulated trading mechanism as well as matrix auction mechanisms for two or three items are especially suitable for supply web co-ordination and optimization tasks.     

MoRVAM: A reverse Vickrey auction system for mobile commerce

Internet auctions bring buyers and sellers together for the purpose of trading goods and services online. In order to get the goods, a buyer must search for items through several auction sites. When the auction starts, the buyer needs to connect to these auction sites frequently so that he/she can monitor the bid states and re-bid. In this paper, we propose an automated negotiation model between two participants, for mobile commerce, using collaborative mobile agents called MoRVAM, which mediates between the buyer and the sellers, and executes bidding asynchronously and autonomously. A new RVT protocol is also implemented to achieve unconditional bid privacy. Advantages of the RVT protocol are addressed as well. All the bidding process can be implemented without revealing losing bid and unnecessary information.     

IntelliBid: An Event-Trigger-Rule-Based Auction System over the Internet

This paper presents the design and implementation of an Event-Trigger-Rule-Based auction system called IntelliBid. A network of Knowledge Web Servers, each consisting of a Web server, an Event-Trigger-Rule (ETR) Server, an Event Engine, a Knowledge Profile Manager, and Bid Servers and their proxies constitutes IntelliBid. Together, they provide auction-related services to the creator of an auction site and the bidders and suppliers of products. IntelliBid offers a number of desirable features. First and foremost is the flexibility offered to bidders for defining their own rules to control their bids in an automatic bidding process, which frees the bidders from having to be on-line to place bids. By using different rules, the bidders can apply different bidding strategies. Second, it furnishes valuable statistical information about past auctions to both suppliers (or sellers) and bidders. The information can assist a bidder in bidding and a seller in setting a reasonable base price and/or the minimum incremental price. Third, since rules that control the automatic bidding are installed and processed by the ETR servers installed at bidders' individual sites, bidders' privacy and security are safeguarded. The statistical information that is released by IntelliBid only depicts the trend of the bidding prices of a product. The information about bidders is kept completely secret, thus safeguarding the privacy of the bidders. Fourth, IntelliBid's event, event filtering and event notification mechanisms keep both bidders and suppliers timely informed of auction events so that they or their software system can take the proper actions in the auction process. Fifth, any registered user of IntelliBid, bidder or supplier, can monitor the bids placed to any product being auctioned in IntelliBid. Sixth, IntelliBid allows bidders to do both on-line (or manual) bidding and automatic bidding. It also allows a bidder to participate in several auctions at the same time, in both manual and automated modes. The bidding of a product can depend on the result of the bidding of another product. Last, but not least, IntelliBid allows a person or organization to play both the role of bidder and the role of supplier simultaneously. The Profile Manager keeps the information as a bidder and information as a supplier separately. Moreover, IntelliBid's architecture uses a parallel event management system to do event registration and notification. This paper also reports the result of a performance study on the implication of using such a parallel system to achieve scalability.     

An adaptive algorithm for tolerating value faults and crashfailures

The AQuA architecture provides adaptive fault tolerance to CORBA applications by replicating objects and providing a high-level method that an application can use to specify its desired level of dependability. This paper presents the algorithms that AQUA uses, when an application's dependability requirements can change at runtime, to tolerate both value faults in applications and crash failures simultaneously. In particular, we provide an active replication communication scheme that maintains data consistency among replicas, detects crash failures, collates the messages generated by replicated objects, and delivers the result of each vote. We also present an adaptive majority voting algorithm that enables the correct ongoing vote while both the number of replicas and the majority size dynamically change. Together, these two algorithms form the basis of the mechanism for tolerating and recovering from value faults and crash failures in AQuA     

Real-time detection of shill bidding in online auctions: A literature review

Online auctions have become an increasingly popular and convenient way for conducting ecommerce transactions on the Web. However, the rapid surge of users participating in online auctions has led to auction fraud. Among the types of auction fraud, the most prominent is Shill bidding. Shill bidding is intentionally fake bidding by a seller on his/her own auction to inflate the final price. This can be accomplished either by the seller himself/herself or by someone colluding with the seller to place fake bids on his/her behalf. Therefore, it is difficult to manually investigate the large amount of auctions and bidders for shill bidding activities. Detecting shill bidding in real-time is the most effective way to reduce the loss result of the auction fraud. Researchers have proposed multiple approaches and experimented to control the losses incurred due to shill bidding. This paper investigates the real-time detection techniques of shill bidding. It also provides a brief overview of major work that has been conducted in shill bidding detection including both offline and real-time approaches. Furthermore, this paper identifies research gaps in the detection and prevention of shill bidding behaviours. It also provides future research issues and challenges to detect shill bidding in real-time.     

一个基于知识证明签名的安全电子拍卖协议

论文研究了英式电子拍卖协议,基于知识证明签名给出一个安全有效的电子拍卖协议。该协议实现了竞拍者身份的匿名性、获胜竞拍者的不可否认性、可公开验证性、竞拍者不可伪装性、可跟踪同一拍卖中某竞拍者的投标以及某个竞拍者在不同拍卖中不可关联性等问题。论文的工作重点是引入了可信第三方并利用知识证明签名来解决其它协议中撤消竞拍者的问题,可简单地撤消某个竞拍者并保证拍卖的高效率。另外,本文还给出了避免拍卖管理者的不公正性的改进协议。     

Design of online auctions: Proxy versus non-proxy settings

Recent years have witnessed the rapid development of online auctions. Currently, some online auctions, such as eBay, introduce a proxy bidding policy, under which bidders submit their maximum bids and delegate to a proxy agent to automatically outbid other competitors for the top bidder, whereas other online auctions do not. This paper compares these two widely used auction mechanisms (proxy setting and non-proxy setting) and characterizes the equilibrium bidding behavior and the seller's expected revenue. We find the proxy auction outperforms the non-proxy auction in terms of the seller's expected revenue. This dominance result is not prone to the specific bid announcement policy, the bidder's knowledge regarding the number of bidders, the impact of traffic congestion along the bidding process, the number of items sold through the auction, and the existence of a reserve price.We further find that the proxy setting usually fails to sustain the truthful bidding as a dominant strategy equilibrium even if no minimum bid increments are adopted, and the possibility of a low-valuation-bidder dilemma where the low-valuation bidders could be better off if all bidders collude to bid at the last minute. We also discuss the dramatically different equilibrium bidding behaviors under the two auction mechanisms.     

Strong activity rules for iterative combinatorial auctions

Activity rules have emerged in recent years as an important aspect of practical auction design. The role of an activity rule in an iterative auction is to suppress strategic behavior by bidders and promote simple, continual, meaningful bidding and thus, price discovery. These rules find application in the design of iterative combinatorial auctions for real world scenarios, for example in spectrum auctions, in airline landing slot auctions, and in procurement auctions. We introduce the notion of strong activity rules, which allow simple, consistent bidding strategies while precluding all behaviors that cannot be rationalized in this way. We design such a rule for auctions with budget-constrained bidders, i.e., bidders with valuations for resources that are greater than their ability to pay. Such bidders are of practical importance in many market environments, and hindered from bidding in a simple and consistent way by the commonly used revealed-preference activity rule, which is too strong in such an environment. We consider issues of complexity, and provide two useful forms of information feedback to guide bidders in meeting strong activity rules. As a special case, we derive a strong activity rule for non-budget-constrained bidders. The ultimate choice of activity rule must depend, in part, on beliefs about the types of bidders likely to participate in an auction event because one cannot have a rule that is simultaneously strong for both budget-constrained bidders and quasi-linear bidders.     

Repeated Budgeted Second Price Ad Auction

Our main goal is to abstract existing repeated sponsored search ad auction mechanisms which incorporate budgets, and study their equilibrium and dynamics. Our abstraction has multiple agents bidding repeatedly for multiple identical items (such as impressions in an ad auction). The agents are budget limited and have a value per item. We abstract this repeated interaction as a one-shot game, which we call budget auction, where agents submit a bid and a budget, and then items are sold by a sequential second price auction. Once an agent exhausts its budget it does not participate in the proceeding auctions. Our main result shows that if agents bid conservatively (never bid above their value) then there always exists a pure Nash equilibrium. We also study simple dynamics of repeated budget auctions, showing their convergence to a Nash equilibrium for two agents and for multiple agents with identical budgets.     

A new bidding framework for combinatorial e-auctions

Bidding languages define the means through which participants in an electronic auction define bids and express requirements on their execution. The current state of combinatorial auction market design indicates that no existing bidding language is general enough to support auctions of both divisible and indivisible commodities. In this paper, we propose a novel bidding framework based on a two-level representation of a combined bid. At the inner level, bidding operators impose conditions on the executed proportions of packages of atomic single-item bids. Partial bids defined this way are then recursively combined through logical operators to produce a final combined bid that is submitted to the auctioneer. We present a formal specification of the framework, and analyze how it impacts the mathematical programming formulation of the allocation problem. An application in the context of combinatorial auctions of financial assets illustrates the utilization of the proposed bidding framework.