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Empirical hardness for mixed auctions

Mixed Multi-Unit Combinatorial Auctions (MMUCAs) offer a high potential to be employed for the automated assembly of supply chains of agents. However, little is known about the factors making a winner determination problem (WDP) instance hard to solve. In this paper we empirically study the hardness of MMUCAs: (i) to build a model that predicts the time required to solve a WDP instance (because time can be an important constraint during an auction-based negotiation); and (ii) to assess the factors that make a WDP instance hard to solve.

Assistant agents to advice users in hybrid structured 3D virtual environments

Hybrid structured 3D Virtual Environments model serious activities in immersive 3D spaces, where participants are human and software agents, and their interactions are regulated by an Organization Centered Multi‐Agent System (OCMAS). In this context, both OCMAS social model and the tasks that users need to accomplish can be rather complex, and thus, users may benefit from having an assistance service. Hence, we propose personal assistant agents (PA), which, based on knowledge about the OCMAS specification and current system state, provide the user with an advice (a plan) to achieve her or his goal. Additionally, we implement this service with PLAN-EA, an Extension of the A *  algorithm that generates plans for a user whose actions may depend on other users’ actions. Thus, PAs provide plans that do not only include assisted user actions but also other users’ ones. We illustrate our approach by means of v‐mWater—an online water market—and make a comparative analysis, with and without assistance, where efficiency—in terms of number of user actions—shows an improvement (7 vs 10.8), efficacy—percentage of completed tasks—also improves (93% vs 77%), and assistances overall satisfaction is positive. Copyright

v-mWater: An e-Government Application for Water Rights Agreements

Nowadays, governments are increasingly taking advantage of Information and Communication Technologies to provide services over the internet (the so-called e-Government applications) to citizens, businesses, employees, and agencies. We argue that e-government services will benefit from being distributed and intelligent, and thus, that they can be modelled as Multi-Agent Systems (MAS). The field of MAS focuses on the design and development of systems composed of autonomous entities which interact within an environment in order to achieve their common or individual goals. Nevertheless, although humans can be seen as autonomous entities, most MAS methodologies and infrastructures do not consider direct human participation. In general, the human role is limited to acting behind the scenes by customising provided agent templates. The resulting agents participate in the system on humans’ behalf. In order to overcome this limitation we propose using 3D Virtual Worlds, which is one of a very few technologies that provides all the necessary means for direct human inclusion inside software systems. 3D Virtual Worlds are 3D graphical environments where humans participate represented as graphical embodied characters (avatars) and can interact there by using simple and intuitive control facilities. We advocate that 3D Virtual Worlds technology can be successfully used for “opening” multiagent systems to humans. This idea is used in Virtual Institutions, which combine Electronic Institutions and 3D Virtual Worlds to engineer applications where participants may be human and software agents. In this chapter we present the prototype v-mWater, a virtual market based on trading Water. It is an e-Government application in the agriculture domain modelled as a Virtual Institution where participants are irrigators and employees of a hydrographic basin. We present the specification of the system, the virtual world generation from this specification and its deployment using the Virtual Institution eXEcution Environment (VIXEE). Finally, we show an example execution of our virtual market in order to illustrate the advantages of our approach.

An infrastructure for human inclusion in MAS

The field of Multi-Agent Systems (MAS) focuses on the design and development of systems composed of autonomous entities (i.e. agents) which interact in order to perform specific activities. In general, direct human participation in these systems is not considered. We advocate that 3D Virtual Worlds technology can be used to facilitate human inclusion in a MAS system. In this demo we present an infrastructure, the Virtual Institutions eXEcution Environment (VIXEE), which allows direct human participation in MAS providing an immersive experience.

Including Conversational Agents into Structured Hybrid 3D Virtual Environments

Structured Hybrid 3D Virtual Environments are 3D virtual spaces where staff (organisational) software agents support human users in their task achievement. These systems are characterized by: i) being hybrid, so that humans and software agents can interact; and ii) being structured and task oriented, so that interactions are regulated by a subjacent Organisation Centered Multi Agent System (OCMAS)-an Electronic Institution (EI). The contribution of this paper is to include task-oriented conversational staff bots (i.e. the embodiment of staff agents in the 3D environment) that communicate with users by using natural language. With this aim, we extend the Artificial Intelligence Mark-up Language (AIML) with special tags to enable complex task-oriented conversations whose flow needs to consider both the states of the conversation and the ontology related to the task. We evaluate the usability of our conversational proposal and compare it to a previous command-based interaction system. Results show the conversational approach presents a higher user satisfaction than the command-based one. Moreover, in average, it also performs better in terms of efficiency, effectiveness and errors.