Facilitating e-Negotiation Processes with Semantic Web Technologies Dickson K.W. Chiu1, Senior Member, IEEE, S. C. Cheung2 Senior Member, IEEE, Patrick C. K. Hung3 and Ho-fung Leung4 1 Dickson Computer Systems, Hong Kong Department of Computer Science, Hong Kong University of Science and Technology 3 Faculty of Business and Information Technology, University of Ontario Institute of Technology, Canada 4 Department of Computer Science and Engineering, The Chinese University of Hong Kong email: dicksonchiu@ieee.org, scc@cs.ust.hk, Patrick.Hung@uoit.ca, lhf@cse.cuhk.edu.hk 2 Abstract Semantic Web technologies have recently been maturing to make e-commerce interactions and crossorganizational processes more flexible and automated. Ontology has also been developed in various business domains. However, researches in Semantic Web have largely focused on the facilitation of successful matchmaking but not much on the negotiation upon matchmaking failures and exceptions. In this paper, we propose a novel application of Semantic Web technologies for the facilitation of e-Negotiation processes. We discuss how the elicitation of negotiation issues, alternatives, and tradeoff can be streamlined. We further propose a novel methodology for the elicitation of dependencies among negotiation issues so that negotiators can focus on tradeoff among inter-related issues, instead of arguing about single issues. A negotiation plan can thus be derived to observe negotiation orders across different issues. As a result, negotiators can have a better cognition of their negotiation tasks and the overall e-Negotiation process can be streamlined. We are extending a negotiation support system to demonstrate the feasibility of our approach, which is the most useful to repeatable and semi-structured negotiations in businessto-business (B2B) e-Commerce and e-Marketplace environments. 1. Introduction Negotiation is a decision process in which two or more parties make individual decisions and interact with each other for mutual gain (Raiffa 1982). The order of a negotiation process should guide the progress of actual business interactions. Proposals are sent to the other parties, and a new proposal may be generated after receiving a counter proposal. The process continues until an agreement or a deadlock is reached, or even one or more parties quit. Each party needs to determine reactions of the other parties and obtain their responses, and each party also needs to estimate the outcomes that the other parties would like to achieve. However, negotiators tend to be ignorant of the others’ values and strategies, especially in a non-cooperative environment. As a result, negotiations may involve high transaction costs and do not always reach the best solution. The Internet has recently become a global common platform where organizations and individuals communicate among each other to carry out various commercial activities and to provide value-added services. However, as many business activities become automated as electronic transactions, negotiation between human can be a bottleneck. A major problem of this is its slowness, which is further complicated by issues of culture, ego, and pride (Raiffa 1982). An automated negotiation system should conduct negotiation to create value by interacting with different parties to create mutually acceptable deals. This is particularly applicable to standard business interactions that could be taken place over the Internet, such as real-estate transactions, purchase and sale of goods, etc. During negotiation processes, understanding the interactions between parties is critical (Griffel 1997). Negotiation often involves the evaluation of several issues and of several alternatives per issue. As a result, a large combination of values has to be evaluated by decision makers, which is time consuming and could be difficult for decision makers from a cognitive perspective. Thus tradeoffs can often be identified when two or more issues are considered simultaneously (Druckman 1977). Most of the related work in negotiations takes the consideration of issues in isolation. Decision makers are assumed to consider the issues one at a time, in a stepwise fashion, instead of integrating multiple issues into a single package so that potential tradeoffs can be recognized (Foroughi and Jelassi 1990). The work described in this paper was supported by a grant from the Research Grants Council of the Hong Kong Special Administrative Region, China (Project No. HKUST6170/03E). Recently, Semantic Web technologies (Fensel et al. 2001, Daconta et al. 2003) have been maturing to make ecommerce interactions more flexible and automated. The Semantic Web provides explicit meaning to the information available on the Web for automated processing and information integration based on the underlying ontology. An ontology defines the terms used to present a domain of knowledge that is shared by people, databases, and applications. In particular, ontologies encode knowledge possibly spanning different domains as well as describe the relationships among them. Ontologies have also been developed in various business domains such as HIPAA (2003). One can imagine that ontologies can help negotiators to better understand the negotiation process. However, researches in Semantic Web have mainly focused on the facilitation of successful matchmaking but not much on the negotiation upon matchmaking failures and exceptions. Yet, ontologies facilitate mutual understanding of negotiators on the negotiation issues and alternatives. Our previous papers (Cheung et al. 2002, 2003) discuss inter-dependencies among issues help formulation of efficient negotiation processes, but do not discuss how to elicit such dependencies systematically. In this paper, we further propose a novel methodology for the elicitation of dependencies among negotiation issues from ontologies so that negotiators can focus on tradeoff among interrelated issues, instead of arguing about single issues. A negotiation plan can thus be derived to observe relationships across issues. As a result, negotiators can have a better cognition of their negotiation tasks and the overall e-Negotiation process can be streamlined. Further, this also offers a basis for checking the completeness of issues and alternatives for the negotiation. The remainder of this paper is organized as follows. Section 2 discusses background and related work. Section 3 presents an e-Negotiation concept model based on which we formulate an methodology of the overall e-Negotiation process. Section 4 describes a motivating example ontology. Section 5 discusses how ontologies are useful in negotiation. Section 6 describes our system architecture and some implementation details. This is followed by discussions and summary in Sections 7. 2. Background and Related Work Computer applications were first employed for negotiation support in the 1960s. In the 1980s, computer-based Negotiation Support Systems (NSS) emerged, and they were typically used for training and research in a laboratory environment but rarely used in practice (Delaney et al. 1997). In general, NSS have the following basic features (InterNeg 2000): (1) a formalism to describe the negotiation activity in terms of choices and outcomes, (2) a way to generally characterize the associated outcome probabilities, and (3) a methodology for processing the model to evaluate the expected value of choice alternatives. NSS normally assist negotiators to assess situations, generate and evaluate alternatives, and implement decisions. NEGOTIATOR (Bui and Shakun 1996) is a classical NSS that seeks to guide negotiators to move their individual goals and judgments to enhance the chance of achieving a common solution. It supports problem adaptation through information sharing, concession making, and problem restructuring or re-framing. However, NEGOTIATOR only helps the negotiators make decisions without explicit support to other entities involved in negotiation. INSPIRE (InterNeg Support Program for Intercultural Research) (Kersten and Noronha 1999) is a webbased prototype for supporting inter-cultural as well as intra-cultural negotiations. It can conduct negotiation anonymously, evaluate the goodness of an offer, and review the history of a negotiation. INSPIRE supports the communication among negotiators by exchanging messages, but it does not directly deal with the interactions among different entities. Analysis by Forrester (2000) research reveal that 18% of global exports will flow online by 2004 and that crossborder electronic marketplaces (e-Marketplace) trade will surpass $400 billion. Despite technical challenges, eMarketplaces have emerged to be important trading platforms in recent years. The popularity of e-Marketplaces is largely attributed to their improvement in economic efficiency, reduction in margins between price and costs, and speeding up complicated business deals (Feldman 2000). Although most e-Marketplaces provide adequate support for product and price discovery, their support for negotiation is far from satisfactory (Cho 2001). Negotiation support is mostly limited to simple bidding functions. There is a lack of general support for bargaining like the proposed mechanism in this paper. Despite rapid automation of the other phases of e-commerce transactions, negotiations are often done by using emails or traditional manual communication technologies such as phones or face-to-face meeting, causing serious overhead costs (Cho 2001). As for negotiation support in e-Marketplaces, Yen et al. (2000) propose an intelligent clearing-house approach that supports both data and textual information about dynamic markets during negotiation, and develops an agentbased prototype Virtual Property Agency. Cho (2001) studies various requirements of negotiation support in eMarketplace and evaluates a number of popular eMarketplaces. The work further provides a framework for designing and evaluating a multi-dimensional auction model. However, these studies do not cover different modes of negotiation comprehensively in one complete framework nor negotiation based on e-contracts. Schoop and Quix (2001) present the negotiation process as the exchange of contracts between the parties in an eMarketplace. The contract contents are presented as extensible semi-structured documents. During the negotiation process, the contract evolves over time until a final agree- Ontology Party * involves Negotiation 2..* Auxiliary Concept 1..* 1 makes 1..* resolves 1 1..* Task * 1..* Base Concept Issue 1 dri ve s Offer maps to * s* 1 1 Accepted Offer * Concept te la mu f or Plan 1..* 1..* 1 * precedes * * indivisibly relates to has 1..* Alternative Value Accepted Alternative Value Fig. 1. Conceptual Model of e-Negotiation in UML Class Diagram ment has been reached or the negotiation is terminated. All these works do not consider relations among issues of negotiation or other fundamental mechanisms relating to the effectiveness of contract negotiation. On the other hand, although Semantic Web technologies are maturing, ontology standards are still forming (Fensel et al. 2001). Challenges remain for reusing available ontological information and researchers focus on information integration. In the past years, there are different standardized languages proposed. For example, DARPA Agent Markup Language (DAML, 2004) is a language created by DARPA as an ontology language based upon the Resources Description Framework (RDF, 2004). DAML-S was designed to serve as the basis for representing descriptions of inverses, unambiguous properties, unique properties, lists, restrictions, cardinalities, pairwise disjoint lists, and data types. The Web Ontology Language (OWL, 2004) is an eXtended Markup Language (XML) proposed by the World Wide Web Consortium (W3C) for defining Web ontologies. OWL ontology includes descriptions of classes, properties, and their instances, as well as formal semantics for deriving logical consequences in entailments. Yu and Mylopoulus (1996) consider dependencies of business goals but not down to the practical details of issue dependencies for negotiation. Phelps et al. (2004) suggest the use of ontology for agent-based negotiation with a focus on the heuristics of bidding strategies of auctions instead of negotiation plan for bargaining support. Lee (2000) points out the use of semantic value and ontology servers with the help of context agents to avoid inconsistency in the exchange of offers during e-negotiation, but not further to the formulation of negotiation plans. Ontology negotiation enables users to cooperate in performing an activity based on different ontologies (Bailin and Truszkowski 2001). Modeled on the patterns of successful human communication, ontology negotiation consists of a series of interpretations and clarifications intended to locate common vocabulary and assumptions (Bailin and Lehmann 2003). However, these studies concerned with how consensus of ontologies can be arrived at. They do not consider further how agreed ontologies can help the formulation of negotiation processes in general, as our novel attempt in this paper. 3. e-Negotiation Process Conceptual Model and our Methodology Whereas much research has focused on supporting negotiation activities with various information technologies, the proposed approach in this paper concentrates on the eNegotiation based on ontologies. In this section, we introduce an e-Negotiation concept model and a methodology to support it. 3.1. e-Negotiation Conceptual Model Fig. 1 presents an e-Negotiation conceptual model in the Unified Modeling Language (UML)(OMG 2001) class diagram based on ontologies. An e-Negotiation is made of up tasks, each of which aims at resolving an issue or a collection of co-related issues. Each of these issues maps to a set of concepts and their relationships based on an agreed ontology. If an issue is mapped into exactly one concept in an ontology, we call this concept a base concept for the negotiation. However, if an issue can break down into several concepts according to an ontology, we call these concepts auxiliary concepts. The agreed ontologies help identify the inter-relationships among the issues and concepts, as well as possible alternatives for issues (as explained in Section 5). An e-Negotiation plan can thus be formulated based on the relationships across these concepts. The plan presents a strategy to drive and organize activity process start condition select agreed relevant ontologies for each collection of co-related issue * map issues into ontology concepts [not consistent] [consistent] derive concept relations check consistency of issues &concepts synchronization bar process termination creation of agreement [all issues are resolved] Pre-negotiation phase formulate plan identify issues [need to revise tradeoff model] [need to identify new issues] identify alternatives evaluate tradeoffs & make offers Negotiation phase [quit] Fig. 2. Ontology Based e-Negotiation Process Model in UML Activity Diagram various tasks in an e-Negotiation. Multiple offers and counter offers are made in a task until a consensus has been reached. A task in an e-Negotiation represents some work that needs to be executed by a set of parties that can be a negotiator, or even a program such as Negotiation Support Systems (NSS) to resolve a specific issue. 3.2. Methodology for Ontology based e-Negotiation Process Formulation Fig. 2 summarizes our proposed methodology for formulation of e-Negotiation processes based on ontologies in the notation of UML activity diagram. This negotiation process is driven by our conceptual for e-negotiation as described in previous sections. Both parties have to participate in each constituting activity of the process, which consists of two major phases: pre-negotiation and negotiation. Although the pre-negotiation phase looks complicated, it is based on the most common and logical way of analyzing the issues with ontologies (as detailed in Section 5). We do not preclude other possible sequences for negotiation plan formulation. In particular, negotiation plans once elicited can be stored in a repository for reuse and adaptation. That means, if negotiators agree, they may just pick a negotiation plan from the repository and starts right away. Therefore, our approach is the most suitable for negotiations in e-marketplaces or B2B e-commerce, where semi-structured negotiations are often repeated and negotiation efficiency is important. The e-Negotiation process leads either to a successful creation of an agreement or to nothing. Note that only through mutual concessions can the negotiation process reach an agreement. The following steps further elaborate on our methodology. 1. First of all, the negotiators have to determine the issues to be negotiated. 2. At the same time, commonly agreed ontologies are selected to help the elicitation of issues. 3. Issues are related to the concepts in the selected ontologies. 4. Check all the dependencies of concepts that constitute the issues from the (refined) ontology map. Mutually dependent clusters of concepts determine the indivisible group of negotiation issues that have to be negotiated together so that effective tradeoff can be evaluated. 5. Check the consistency of all the concepts, issues, and their dependencies (Cheung et al. 2002). 6. For a consistent plan, we can proceed to elicit the possible alternatives for negotiation; otherwise we have to re-iterate from step 3. 7. According to the dependencies, we can formulate a precedence graph of the issues and issue groups. Based on the precedence graph, efficient negotiation plan can be determined to exploit the maximum possible concurrency. The progress of a negotiation can be thus visualized. 8. Negotiators are then ready to make or evaluate offers and counter-offers based on the plan. An agreement is successfully created when all issues have been resolved. 9. Should new issues arise during the negotiation phase (say, due to incomplete specification), repeat from step 3 to analyze the new issue and its relationships to existing ones. In real-life, the formulation of a negotiation plan may involve several iterations before attaining the consensus of all negotiators. This reflects the interrelationships among the parameters may not often be captured precisely in one-shot. 4. Motivating Example Sale negotiation activities are the most common in ecommerce and particularly in e-marketplaces. Ontologies help e-commerce activities through mutual understanding Discount Total Amount {unordered} attributes: deposit, installment, payupon-delivery, … Sale Order Payment Terms * Order Line Quantity Appearance {ordered} attributes: small, medium, large, extra-large Size {unordered} attributes: brick red, crimson, … Unit Cost Shipping Cost Payee Delivery Delivery Date Refunding Policy Insurance Insured Amount Premium Color Red Insurer Purple {unordered} attributes: light purple, magenta, … Fig. 3. An Ontology for Sale Negotiation of Rubber Gloves in UML Class Diagram and the facilitation of information exchange (Fensel et al. 2001). Fig. 3 presents an example ontology for the negotiation over a selection of concepts in a sale order of rubber gloves. Concepts are represented in rectangular boxes. A Sale Order may consist of multiple Order Lines, each of which describes the Quantity to be ordered, Appearance and Unit Cost. Appearance consists of Size and Color. The former may attains a value ranging from small to extralarge while the latter can be further classified into different specific color concepts, such as Red, Purple, and so on. Besides the Order Lines, a Sale Order is characterized by the information about Payment Terms, Discount, Refunding Policy, and the Total Amount of the order. Delivery involves three issues: Shipping Cost, Delivery Date, and the associated Insurance. In addition, directed lines show the dependent relationships among concepts and lines without arrows denote bi-directional relationships. Planning is a critical part of negotiation. There is usually one major issue (e.g., price), and several minor issues (e.g., insurer) in any negotiation. In negotiation, there are three types of planning (Lewicki and Litterer 1985): (1) Strategic planning is used to define long-range goals and to position oneself toward long-rang goals, (2) Tactical planning is the process of developing short-range tactics and plans to achieve long-range goals, and (3) Administrative planning is the process by which both manpower and information are marshaled to make the negotiation proceed smoothly. Therefore, we have to establish a negotiation plan, depicting an order to discuss those issues. Traditionally, the functions of the negotiating plan (Marsh 1987) are to define the initial strategy with the supporting arguments. The initial strategy includes the order of issues to be negotiated. In the next section, motivated by this sale order example, we discuss how ontology helps formulate a negotiation plan. Furthermore, we discover different types of relations among negotiable concepts. Based on these relations, we can determine a negotiation plan that facilitates collaborative negotiation processes. 5. Are Ontologies Helpful? In this section, we discuss how ontologies help the overall formulation negotiation process. Though the use of ontologies in groupware and collaboration systems is not new, we show how ontologies can be applied in a much wider and important scope in negotiation processes. 5.1. Understanding Negotiation Issues from Ontologies The difficulties during the exchange communication between users are the inconsistency in the represented value and how to make the data interchange meaningful. Thus, ontologies are becoming increasingly important as a component of online commerce offerings. Ontologies can present machine-understandable semantics of data to facilitate the negotiation about products, or help automatically configure products and services according to specified requirements. In particular, shared and agreed ontologies provide common definitions of the terms to be used in the subsequent negotiation processes. We propose the following methodology extended from well-known graph search algorithms (Cormen 2001) to enhance the completeness of issues in requirement elicitation: Negotiate Size Negotiate Unit Cost, Quantity & Delivery Date Negotiate Color Negotiate Refund Policy Negotiate Shipping Cost & Payee Negotiate Payment Terms Negotiate Insurance Premium, Insured Amount & Insurer Negotiate Discount Compute Total Amount Fig. 4. A Possible Negotiation Plan for Rubber Gloves Sale in UML Activity Diagram 1. Issues are preliminarily identified in the first round. 2. For each identified issue, check if an issue can be mapped directly to a concept. If not, see if an issue can be refined into a set of more specific concepts, which combined can represent the issue. A typical example is that a cost can be refined into constituent costs that sum up to it. 3. Ontologies are often incomplete and therefore subject to further refinement. New concepts can be introduced to the ontology upon mutual agreement. However, the relation of a new concept to existing ones should be elicited to help understand the concept itself as well as determine potential dependence of issues for the negotiation. 4. For each identified concept c, examine every un-visited node n adjacent to c in the ontology map. 5. For each such node n, see if the new concept is relevant to the negotiation problem. 6. Repeat step 4 and 5 until no more related new concepts can be identified. 7. Only after successful negotiation do we need to consider combining newly identified concepts back to specify a more concise agreement, because we advocate negotiation centered on concepts. 5.2. Understanding Dependencies of Issues from Ontologies As we are mapping issues to concepts in ontologies (as described in the above sub-sections), we also discover their inter-relationships at the same time. Based on concepts in databases and artificial intelligence of computer science, we identify the following typical categories of dependencies among issues. Functional dependency – This is the main type of dependence that motivates this research. The concept is borrowed from fundamental relational database concepts (Elmasri and Navathe 2000). The alternative for an issue is determined by the alternatives(s) of other issue(s). For example, cost of production depends on delivery date and quantity. Computational dependency - This is a more obvious type of functional dependency, which has a hardwired computational formula. For example, insurance amount = percentage * cost of goods. Requirement dependency (constraint satisfaction) – Only after the determinant value is known can viable alternatives be determined. For example, whether a customer may pay by credit card, bank draft, or remittance is evaluated according to the total amount. Therefore, only after the total amount is determined can the negotiation of payment method take place. Classification dependency – This is a special type of requirement dependency in which the classification of another issue is dependent on the outcome of an agreed issue. 5.3. Indivisible Components of Issues for Tradeoff Evaluation and Negotiation Plan Some concepts (and therefore issues) have to be negotiated together at the same time. It occurs when there are cyclic dependencies among the concepts. Such group of concepts is mutually dependent and therefore must be consider altogether for tradeoff as they cannot be individually or sequentially considered during negotiation. After eliciting the dependencies, we can therefore draw a precedence graph (Cormen 2001) of the issues and issue groups for formulating a negotiation plan. Note that in the task “formulate plan”, we construct a detailed process to realize the activity “make offers and counter offers.” Fig. 4 gives a possible process for a scenario negotiating the sale of rubber gloves. The negotiation starts with the issues Size, Color, and Refunding Policy concurrently. Once the Size and Color are decided, the issues of Unit Cost, Quantity, and Delivery Date are then negotiated. The process succeeds with the computation of the Total Amount of the order. Multiplatform Support Subsystem Multi-platform Devices WAP Gateway SMS Gateway Internet Messenger Web Server bids & offers e-Negotiation Executing Subsystem e-Negotiation process e-Negotiation Session Manager e-Negotiation process issue dependency revised ontology, issues e-Negotiation Data & Repository existing ontology Issue Dependency Editor Ontology Maintenance Subsystem Ontology Editor Ontology Generator ontology task dependency Tasks Organizer ontology, issue e-Negotiation Matching Subsystem e-Negotiation Process Generator ontology Search Engine criteria, issues Criteria & Issues Editor Fig. 5. System Implementation Architecture 5.4. Understanding Possible Alternatives for Issues from Ontologies Often, alternative for issues cannot be expressed in numerical values. Alternatives are often in discrete values by its nature, such as country of origin, shipping company, and so on. Alternatives for other issues are often not quantized in normal practices because of difficulties in recognizing them. For example, color is specified by its common name or more professionally in a color code, but rarely expressed in the wavelength of constituent light-waves. In many other occasions, alternatives are not quantized for simplicity and convenience. For example, alternatives for size may be just small, medium, or large because either the issue is not important in the context or a precise value is not required. When a complicated issue is decomposed into concepts, the elicitation of options can be much streamlined. For example, when the issue of appearance is decomposed into the concepts of size, color, and shapes, the alternatives of each concept can then be easily elicited. Ontologies not only can provide sets of alternatives for issues from membership relations, but often also partial or even total explicit ordering of them (e.g., small < medium < large < extra-large). In addition, implicit (partial) ordering may be elicited via inheritance (“is-a”) or composition hierarchies. Thus, such extra knowledge provided by ontologies can further assist negotiators to evaluate offers against their preferences and determine which counteroffers are decreasing the indifferences rather than increasing them. 6. System Architecture and Implementation Fig. 5 shows the implementation architecture for our template driven e-Negotiation support system based on ontologies. The architecture is designed to support eNegotiation processes instantiated from the e-Negotiation conceptual model in Fig. 1 and the methodology in Fig. 2. The design aims to provide flexible and reusable components. The proposed system is acting like a negotiation embellisher who knows the values, beliefs, and constraints of both parties. Then, it seeks an efficient contract that both parties would prefer to the negotiation context they have created (Raiffa 1982). The architecture is made up of four subsystems. The Ontology Maintenance Subsystem allows negotiation parties to specify and edit their negotiation issues and alternatives based on ontologies. The search engine selects the most appropriate ontologies based on a given set of criteria and issues. The retrieved ontology may be further revised using the Ontology editor to address all major required issues and alternatives. Revised ontologies as well as the issues and their alternatives thus derived may be stored in the repository for later retrieval. These data will be used by the e-Negotiation Matching Subsystem to determine a suitable e-Negotiation process based on the issue dependency supplied. The selected e-Negotiation process is then enacted through the e-Negotiation Executing Subsystem. The Multiplatform Support Subsystem provides front-end supports to multiple platform devices, such as WAP, SMS, and Web browsers. [acceptance received] [failure received] [ready to make an offer] Identify the issue(s) to be next negotiated in the plan Prepare reservation prices [counter-offer received] [offer received] [false] Have all issues been negotiated? Evaluate offer / counter-offer [unacceptable offer] [false] Quit? [acceptable offer] Notify counterparty of acceptance start a new negotiation cycle Revise reservation prices Make offer / counter-offer [true] Notify counterparty of failure [true] Successful negotiation Fig. 6. UML Activity Diagram for Making Offers and Counter-offers in a Negotiation Session Fig. 6 depicts our design for maintaining a negotiation session in UML activity diagram. Each negotiation cycle starts with the identification of a set of interrelated issues to be next negotiated, according an agreed negotiation plan (as discussed in the previous sub-section). Each party will then prepare the reservation alternatives (reservation price) of these issues. After that, they may either make an offer to or wait for some offers from counterparties. If a party is not satisfied with the (counter-) offer, another counter-offer or a failure message will be received. A negotiation cycle finishes successfully if an acceptance notification of previous (counter-) offer is received. Finally, the negotiation process succeeds when all issues have been successfully negotiated. Based on this architecture, we have developed an eNegotiation support system with contemporary technologies, including Java applets, Java Server Pages, and Enterprise Java Beans. We are extending the system with support for ontologies with the OWL Web Ontology Language (OWL, 2004) (instead of DAML) because W3C has designed OWL as a standard (Web-Ontology Working Group 2004). OWL has been proposed to provide three increasingly expressive sub-languages for specific communities of implementers and users, namely, OWL Lite, OWL Description Logics (OWL DL), and OWL full. OWL Lite supports the basic need for a classification hierarchy and simple constraints. For example, while it supports cardinality constraints, it only permits cardinality values of 0 or 1. Thus, OWL Lite provides an easier implementation and a quicker migration path for thesauri and other taxonomies. OWL DL supports maximum expressiveness while retain- ing computational completeness (all conclusions are guaranteed to be computed) and decidability (all computations will finish in finite time). OWL DL includes all OWL language constructs, but they can be used only under certain restrictions (for example, while a class may be a subclass of many classes, a class cannot be an instance of another class). OWL DL is so named due to its correspondence with description logic, a field of logic that forms the formal foundation of OWL. OWL Full supports maximum expressiveness and the syntactic freedom of the RDF, but with no computational guarantees. For example, in OWL Full a class can be treated simultaneously as a collection of individuals and as an individual in its own right. OWL Full allows an ontology to augment the meaning of the pre-defined (RDF or OWL) vocabulary. Thus, ontology developers adopting OWL should consider which sublanguage best suits their needs. More specifically, we employ OWL DL because it provides a standard set of elements and attributes with defined semantics, for defining terms and relationships in ontology. In addition, OWL DL contains a set of logic-based primitives that are specifically useful in intelligence informatics. As such, a flexible NSS for different e-Commerce domains and different negotiation plan can be supported, without modifying the underlying system. The negotiators only need to define suitable ontology and derive an effective negotiation plan. This tremendously reduces the development time and costs, and therefore provides a big competition edge under this fast evolving digital economy. 7. Discussions and Summary In this paper, motivated by the recent maturing of Semantic Web technologies, we have developed a conceptual model for e-Negotiation and proposed a pragmatic methodology for e-Negotiation processes formation with the help of ontologies. In particular, we have shown how the elicitation of negotiation issues, tradeoff, and alternatives can be streamlined. We further develop a novel way for the elicitation of dependencies among negotiation issues so that negotiators can focus on tradeoff among interrelated issues, instead of arguing about single issues. Observing the logical order across different groups of issues, we can thus formulate an effective negotiation plan with tradeoff support. By mapping issues onto concepts of agreed ontologies, negotiators can control the openness of issues and our algorithm verifies the completeness of elicited negotiation requirements. We have also built a negotiation support system with the support of issue dependencies to demonstrate the feasibility of our approach, and we are now enhancing it with ontology support. Through our proposed negotiation support mechanisms, negotiation processes are properly guided, recorded, and managed. It also helps simplify the communication messages required across organizations during negotiation activities. Although this could be a serious limitation to general bargaining activities such as political and governmental negotiations, e-commerce activities are usually more structural and repeatable, thereby fitting well into our assumptions. In additional, tradition manual negotiation processes can neither support automation of negotiation (such as through software agents) nor effective integration with Enterprise Information Systems (EIS). As the participants of e-marketplaces often have to evaluate a large number of offers with different options while they are updated frequently of the market news about substitutive products, ontologies help them better understand the offers as well as evaluate and specify their preferences in a stepwise manner. Most of the tasks in the pre-negotiation phase of our negotiation methodology can be prepared by emarketplace administrators based on policies and requirements of the e-Marketplace. Ontologies are specified with reference to relevant industry domains for different categories of products or services. At the same time, common issues and criteria for negotiation can be identified with the typical requirements of the target users. Sample negotiation plans can therefore be formulated are then stored in a repository and available for reuse and user adaptation. Therefore, users of a well-managed e-Marketplace not only enjoy convenience but also the pre-programmed knowledge thus obtained. Further, the negotiation plan (as shown in Fig. 4) comprising a partitioning of the problem facilitates the tradeoff evaluation of complex negotiation issues to be partitioned into separate concerns, each of which may be taken care by an individual group in a large enterprise. For instance, the tradeoff evaluation of (i) payment terms and deposit, and (ii) freight and insurance can be taken care of, respectively, by the purchase department and logistics department of the same enterprise. As such, matching roles or individuals in an enterprise to negotiation tasks can be supported as a higher level separate layer upon the negotiation processes. With the integration of the NSS into enterprise information systems (EIS) or workflow management systems (WFMS) (Chiu et al. 1999, 2001), complicated tradeoff evaluation processes with reference to distributed enterprise data can be streamlined. In addition, management and matchmaking of roles within an organization to negotiation tasks can be taken care by algorithms and methodologies developed for workflow management (Chiu et al. 1999). This is an important direction to be worked out in our continuing research. We further perceive that our proposed highly modular eNSS engine can be plugged into different types of existing e-Marketplaces to enhance their capabilities. In this way, negotiation can be streamlined in a semantic service grid (Gentzsch 2002) consisting of end-users, eMarketplaces, and enterprises, with our ontology based negotiation methodology. Sophisticated decision support and knowledge capturing related to negotiation can be facilitated with ample opportunities for review, reuse, and improvements. This work can be expanded in several directions. From real-life practices, we discover that negotiation sometimes involves classification rules rather than just offers and counter-offers of alternatives. This occurs when negotiator(s) have no alternative for such issues because this is already pre-determined or constrained by other factors that are not changeable. For example, in a sale negotiation, a seller requests the goods to be considered “Hong Kong made” in order to enjoy certain tariff quota. Negotiation of this definition may be argued on the percentage of addedvalue in the goods’ manufacturing process that takes place in Hong Kong. Similar negotiations may also occur when classification rules have ambiguities and incompleteness. 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