ELECTRONIC NEGOTIATION SYSTEMS RUDOLF VETSCHERA University of Vienna, Vienna, Austria SABINE T. KOESZEGI Vienna University of Technology, Vienna, Austria MAREIKE SCHOOP University of Hohenheim, Stuttgart, Germany Negotiations are a particular form of com- munication and collective decision-making. Like all forms of collective action, negotia- tions involve different parties, which can be individuals, groups, or organizations. Three characteristics distinguish negotiations from other forms of collective decision-making as group decisions or social choice (voting) pro- cedures: • There is some conflict of interest between the parties involved. • An agreement can be reached only by consent of all parties. If parties are not able to reach consensus, one particular outcome (usually the status quo) will take place. • An agreement is not reached immedi- ately but involves an interactive process in which offers are exchanged until a mutually acceptable solution is found. Research on electronic systems to support negotiations began in the 1980s as an extension to the concept of decision support systems. Early research on negotiation support systems (NSS), for example, Ref. [1], focused on the multiperson aspect of nego- tiations and the possibilities of information technology to connect parties across time and space. The latter aspect gained impor- tance with the rise of the internet and Wiley Encyclopedia of Operations Research and Management Science, edited by James J. Cochran Copyright  2013 John Wiley & Sons, Inc. the development of web-based NSS [2]. Nowadays, we can distinguish between communication-, decision-, and document- oriented approaches [3]. Surprisingly, e-mail is often used for business negotiations although it does not offer decision support or advanced communication support [4]. Connecting parties is only one function of NSS. As NSS were often seen as an exten- sion to individual DSS, the potential of NSS to improve decision-making is an important concern. Lim and Benbasat [5] distinguished two main components in the architecture of an NSS, a decision support component and a communication support component, and pos- tulated that these two components would have different impacts on negotiations. The concept of decision support in negoti- ations draws attention to another important difference between individual and collective decision problems: in individual decision sup- port, a support system assists a decision- maker to better achieve his or her objectives. Decision support in negotiations can have two different goals: supporting one party to better achieve its own goals vis- ` a-vis others or to support all parties to achieve higher level goals such as efficiency or fairness. In the latter case, the systems take the role of a neutral third party, and in the former case, they serve as advisors to one party. Mod- ern negotiation theory, in particular negoti- ation analysis developed by Raiffa [6] and Sebenius [7], emphasizes the fact that these two goals are not necessarily in conflict and that finding win–win solutions that bene- fit all parties is important. However, most negotiations contain distributive elements in which the interests of parties are in conflict. Therefore, already early concepts of NSS [8] distinguished between support components for individual parties and decision support for a mediator. As negotiations by defini- tion require consensus to reach an agree- ment, supporting parties to find a mutually acceptable solution, and breaking deadlocks in negotiations, is also an important goal of negotiation support at the collective level. 1