Jean Botev

Hybrid Societies: Challenges and Perspectives in the Design of Collective Behavior in Self-Organizing Systems

Hybrid societies are self-organizing, collective systems, which are composed of different components, for example, natural and artificial parts (bio-hybrid) or human beings interacting with and through technical systems (socio-technical). Many different disciplines investigate methods and systems closely related to the design of hybrid societies. A stronger collaboration between these disciplines could allow for re-use of methods and create significant synergies. We identify three main areas of challenges in the design of self-organizing hybrid societies. First, we identify the formalization challenge. There is an urgent need for a generic model that allows a description and comparison of collective hybrid societies. Second, we identify the system design challenge. Starting from the formal specification of the system, we need to develop an integrated design process. Third, we identify the challenge of interdisciplinarity. Current research on self-organizing hybrid societies stretches over many different fields and hence requires the re-use and synthesis of methods at intersections between disciplines. We then conclude by presenting our perspective for future approaches with high potential in this area.

Epidemic Self-Synchronization in Complex Networks of Kuramoto Oscillators

In this article, we present and evaluate an epidemic scheme for the synchronization of coupled Kuramoto oscillators in communication networks. It addresses the problem of efficiently providing globally synchronous time epochs in complex, dynamic Peer-to-Peer network topologies. Rather than the usual model of continuously coupled nodes, a discretized version with sporadic message-based couplings to nearest neighbors is considered. This article empirically studies the emergence of coherent oscillator states for different network topologies, coupling functions, and sporadic coupling intensities. It further investigates the protocols minimum bandwidth requirements in small-world network topologies. Synchronization resilience under the effect of random perturbations is studied for two coupling variations. Finally, the potential utilization of the scheme for a local inference of global network topology characteristics is discussed.

Elastic Consistency in Decentralized Distributed Virtual Environments

Distributed virtual environments like online games or 3D virtual worlds have become very popular in the last few years and a more substantial surge in popularity and use is expected. Because of the huge number of users, such environments will undergo a change of infrastructure from a centralized to a decentralized one, making higher demands on consistency issues. This paper addresses consistency problems which may occur in distributed virtual environments and introduces the elastic consistency model to tackle these problems. According to elastic consistency, different consistency levels setting up a trade-off between consistency and responsiveness of the environment should be introduced in order to provide an efficient way of interaction on a global scale.

HyperVerse: simulation and testbed reconciled

When dealing with dynamic large-scale topologies such as those underlying Peer-to-Peer (P2P) Distributed Virtual Environments (DVEs), one inescapably reaches the point where either: a) simulations lack human behaviour and assessment or where b) practical experiments on a small scale do not yield significant results. The restrictions resulting from the separation of simulation and testbed environments hinder a comprehensive assessment and efficient development of adaptive algorithms and techniques for DVEs as they are investigated in our HyperVerse research project. In this paper, we present a hybrid evaluation system designed to combine the advantages of simulations and testbeds. The proposed infrastructure exhibits great flexibility particularly alluring in view of the multitude of potential research in the context of DVEs.

P2P-Based Avatar Interaction in Massive Multiuser Virtual Environments

The idea of the 3D Web as a global scale Distributed Virtual Environment (DVE) currently is very popular and a lot of research work is done in this field. In the course of the HyperVerse project we have developed a two-tier Peer-To-Peer (P2P) architecture as basic infrastructure for a federated, open and scalable 3D Web. Our approach relies on a concept that incorporates a loosely-structured P2P network overlay of user clients and a highly-structured overlay that connects a federation of reliable server machines constituting a reliable backbone service. A central problem when intending to build a massive virtual online environment is how avatar interaction as well as tracking and provision of avatar positions can be realized in a globally scalable manner. This paper presents a hybrid avatar interaction scheme developed for HyperVerse that incorporates the user clients and the backbone service for avatar position tracking. The backbone is used as reliable fall-back service, while the avatar tracking is handled in a pure P2P fashion whenever possible. This way backbone overload is prevented in a self-organizing manner whenever client density tends to overburden the backbone infrastructure.

The Snippet Platform Architecture - Dynamic and Interactive Compound Documents

Compound documents in desktop environments face many issues and limitations in terms of modularity and genericity with regard to their representation and handling. The Snippet Platform natively supports highly dynamic and interactive compound documents. The contents of a document are not limited to combinations of traditional types like text, images, vector objects, or videos, but are completely generic and thus may even consist of fully-functional embedded applications. These can be operated in-place, enabling a higher level of interactivity. Moreover, complex dependencies within or in between documents are supported. The component-based architecture of the Snippet Platform allows for keeping these in a consistent working state. It realizes application software by an extensible set of functional modules that are designed to interoperate. These may also be combined for performing more advanced transformations on contents or defining more refined algorithmic dependencies. A fine-granular model, based on so-called Snippets instead of files, ensures the persistent representation of such compound documents and their dependencies. A working prototype, also discussed in this paper, incorporates all these aspects.

The snippet system - Reusing and connecting documents

This paper presents the Snippet System, a new operating system environment that aims at providing enhanced document management facilities. For this, the proposed system utilizes a novel document model based on finer-grained entities, so-called Snippets. These support Relations, which capture the context of individual document excerpts. Snippets furthermore enable a flexible reuse of documents, i.e., user-defined excerpts can be included in several other documents with only selected properties remaining synchronized between different instances. Moreover, dedicated mechanisms allow for the efficient retrieval of these instances and thus support the user in keeping track of reused excerpts and synced properties. While the Snippet Systems concepts extend into the application and user interface layers, this paper focuses in particular on the design and prototypical implementation of its document model, describing how the reuse of document excerpts, the synchronization and retrieval of their different instances, and Relations are supported in a natural and scalable way.

Collaborative filtering via epidemic aggregation in distributed virtual environments

The ever-increasing amount of available information in todays digital society necessitates inline techniques for determining the most relevant content. Collaborative filtering (CF) systems have proven to be an adequate means for reducing informational overload and generating useful recommendations. Current systems are predominantly built on centralized or, more recently, structured Peer-to-Peer (P2P) approaches. However, in order to apply collaborative filtering to large-scale distributed virtual environments (DVEs) in unstructured networks with substatially higher user numbers, different approaches are necessary. Within this paper we present a collaborative filtering algorithm for DVEs utilizing epidemic data aggregation based exclusively on local information. Designed to be extremely scalable, it creates recommendations in a transparent way by distributing an accumulated view of favorite ratings to interacting users. The algorithm is intended for deployment in the HyperVerse - a self-organizing middleware service for large-scale DVEs - for generating and managing rating predictions of object favorites. Evaluation results show that, in terms of quality, locally aggregated predictions converge well on those obtained from an idealized global view.

Socially-Sensitive Systems Design: Exploring Social Potential

In human society, individuals have long voluntarily organized themselves in groups, which embody, provide and/or facilitate a range of different social concepts, such as governance, justice, or mutual aid. These social groups vary in form, size, and permanence, but in different ways provide benefits to their members. In turn, members of these groups use their understanding and awareness of group expectations to help determine their own actions, to the benefit of themselves, each other, and the health of the group.

CollaTrEx – Collaborative Context-Aware Mobile Training and Exploration

This paper introduces the CollaTrEx framework for collaborative context-aware mobile exploration and training. It is particularly designed for the in-situ collaboration within groups of learners performing together diverse educational activities to explore their environment in a fun and intuitive way.