Distributed Systems and Mobile Agents

Most of the research activity developed in last few years focused on the study of mobile and distributed systems.

Control and coordination of a set of autonomous mobile robots. In collaboration with N. Santoro (Carleton University), P. Flocchini (Ottawa University), P. Widmayer e M. Cieliebak (ETH Zurigo), and V. Gervasi (Università di Pisa).

This research topic focuses on the design and analysis of algorithms to control and coordinate a set of autonomous mobile robots that are allowed to freely move on a two dimensional plane. The major goal of this work is to understand from a computational point of view the relationship between the power and the capabilities of the robots and the ability of the team to accomplish the assigned tasks. One of the outcomes of this work has been the design of a computational model to describe a distributed system populated by a set of mobile robots. The most innovative feature that distinguished the model from the previous ones present in the literature was the total asynchrony of the interactions of the robots; in fact, in previous models, the interactions between robots were modeled mostly in a synchronous way. Other results concerned the design of algorithms designed in the proposed model, that allowed the team of the robots to solve tasks that are common in robotics, such as pattern formation, gathering or homing, flocking.

Black hole search. In collaboration with N. Santoro (Crleton University), P. Flocchini (Ottawa University), and Stefan Dobrev (Ottawa University).

This research topic relates to security in networked environments where mobile agents compute. In these environments, in fact, security is the most pressing concern, and possibly the most difficult to address. The interest has been in the presence of harmful hosts, called black holes: sites that destroy any agent that might visit them without leaving any observable trace. This kind of threat exists not only on unregulated non-cooperative settings, such as Internet, but also in environments with regulated access and where agents cooperate towards common goals (e.g., sharing of resources or distribution of a computation on the Grid). In fact, a local (hardware or software) failure might render a host harmful. The focus of the research has been to design efficient strategies for the agents to locate and isolate these harmful presences, evidencing the crucial importance of addressing security issues while searching and exploring a network. Recently, the problem of addressing a wider scenario ---  the so called "dangerous networks" --- is being tackled, where security issues being dynamic and evolving over the time are studied.

Safe-Routing. In collaboration with N. Santoro (Carleton University), P. Flocchini (Ottawa University), L. Pagli (Università di Pisa), P. Widmayer (ETH Zurigo) e T. Zuwa (University of Botswana, Gaborone).

This part of the research activity has been devoted to the study of fault-tolerant routing strategies in networks. In particular, in systems using shortest-path routing tables, a single link failure is enough to interrupt the message transmission by disconnecting one or more shortest-path spanning trees. The on-line recomputation of an alternative path or of the entire new shortest path trees, rebuilding the routing tables accordingly, is usually rather expensive and causes long delays in the message’s transmission. The focus has been on the design of efficient distributed algorithms to precompute, for each link in the tree, a single non-tree link (the swap edge) able to reconnect the network should the first fail. The strategy, called point-of-failure swap rerouting is simple: normal routing information will be used to route a message to its destination. If, however, the next hop is down, the message is first rerouted towards the swap edge; once this is crossed, normal routing will resume. The work focused on distributively identifying the swap edges satisfying several optimazation criteria, such as the  distance between the point of failure and the root, or the sum of the distances of all nodes below the point of failure and the root.

Parallel Algorithms

This study is focused on the design of paralle algorithms for the Coarse-Grained Parallel Machine (CGM). In particular, we study computation geometry algorithms and algorithms on graphs. In collaboration with F. Dehne (Carleton University), and A. Pietracaprina (Università di Padova).

You can find more information on my publications page....

Conference PC and Organization

  • OPODIS 2012 (PC member)
  • OPODIS 2010 (PC member)
  • SIROCCO 2007 (co-chair)
  • FUN 2007 (PC member, Organizer and Proceedings co-editor)
  • SIROCCO 2006 (PC member)
  • OPODIS 2006 (PC member)
  • Eighth International Symposium on Stabilization, Safety, and Security of Distributed Systems -- SSS 2006 (PC member)
  • OPODIS 2005 (PC member, Organizer and Proceedings co-editor in LNCS).
  • Third International Conference on FUN WITH ALGORITHMS -- FUN 2004 (PC member)
  • EUROPAR 2004 (Distributed Systems and Algorithms topic), August 2004
  • In the Organizing Committee of the 2nd IFIP International Conference on Theoretical Computer Science (TCS@2002), August 2002, Montreal

Steering Committee