Dear all,

Tomorrows SACT seminar will be given by our special guest

speaker Prof. Bernard Mans (http://www.comp.mq.edu.au/~bmans/).

Title: Exploration of Dynamic Graphs: the case of Periodically Varying Graphs

Abstract:

In this talk, we consider the computability and complexity of the

exploration problem in a class of highly dynamic graphs: periodically

varying (PV) graphs, where the edges exist only at some (unknown)

times defined by the periodic movements of carriers. These graphs

naturally model highly dynamic infrastructure-less networks such as

public transports with fixed timetables, low earth orbiting (LEO)

satellite systems, security guards’ tours, etc.

We establish necessary conditions for the problem to be solved. We

also derive lower bounds on the amount of time required in general, as

well as for the PV graphs defined by restricted classes of carriers

movements: simple routes, and circular routes.

We then prove that the limitations on computability and complexity we

have established are indeed tight. In fact we prove that all

necessary conditions are also sufficient and all lower bounds on costs

are tight. We do so constructively presenting two worst case optimal

solution

algorithms, one for anonymous systems, and one for those with distinct

nodes ids. An added benefit is that the algorithms are rather simple.

This work is joint work with Paola Flocchini (Ottawa U.) and Nicola

Santoro (Carleton U.).

Time: Tomorrow (Thursday ) 11-12.

Venue: NICTA Seminar room at level 5 in the SIT building

The program for the SACT seminars can be found on:

http://sact.it.usyd.edu.au

Cheers,

Joachim

NICTA | Locked Bag 9013 | Alexandria NSW 1435

T +61 02 8306 0758 | F +61 2 8306 0771 | M 0423 070 859

joachim.gudmundsson

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