i++ School Newsletter

Week commencing 8 December 2008

Previous Newsletters

IEEE CIG 2008 Tutorial

Simon Lucas will present a 2-hour tutorial entitled Learning to Play Games at IEEE CIG 2008.
 
The tutorial provides a practical introduction to game strategy learning with function approximation architectures, covering two main approaches to learning game strategy: evolution (including co-evolution), and temporal difference learning. The tutorial will show how the selected input features and the function approximation architecture has a critical impact on what is learned, as well as how it is interfaced to the game (e.g. as a value estimator or as an action selector). In addition to multi-layer perceptrons attention is also given to N-Tuple systems and interpolated table-based approximators as they have recently shown great potential to learn quickly and effectively. 
 
CIG 2008 is the fourth conference in the series, the first one being held at the University of Essex in 2005. Highlights of the 2008 conference include a keynote talk from Jonathan Schaeffer, whose team recently solved the game of Checkers, showing the result to be a draw if each player plays perfectly.   For more details of the CIG conference series see the CIG website.

PhD Awarded

Congratulations to Edgar Galvan-Lopez who passed his PhD viva on Wednesday 10 December.  Professor Riccardo Poli supervised Edgar’s thesis – “An analysis of the effects of neutrality on problem hardness for evolutionary algorithms”. Edgar completed his PhD within four years, also finding time to produce over 12 other publications during this period, including a chapter of a book, a journal article and several peer-reviewed international conference papers. Edgar served as a reviewer for IEEE Transactions on Evolutionary Computation and on the Journal of Scheduling and also designed and implemented a website in the Health and Human Sciences Department to help health care professionals enhance their knowledge using internet-based scenarios.
 
He has accepted a Post Doctorate position at University College Dublin where he will be working with Michael O'Neill and Anthony Brabazon. Edgar will be studying new operators that can be applied in Grammatical Evolution and he tells us that he is very excited about this project!

Preprint Published

Sangwine, S. J. and Alfsmann, D.,Determination of the biquaternion divisors of zero, including the idempotents and nilpotents, e-print arXiv:0812.1102, 8 December 2008, available at http://arxiv.org/abs/arxiv:0812.1102

Abstract - The biquaternion (complexified quaternion) algebra contains idempotents (elements whose square remains unchanged) and nilpotents (elements whose square vanishes). It also contains divisors of zero (elements with vanishing norm). The idempotents and nilpotents are subsets of the divisors of zero. These facts have been reported in the literature, but remain obscure through not being gathered together using modern notation and terminology. Explicit formulae for finding all the idempotents, nilpotents and divisors of zero appear not to be available in the literature, and we rectify this with the present paper. Using several different representations for biquaternions, we present simple formulae for the idempotents, nilpotents and divisors of zero, and we show that the complex components of a biquaternion divisor of zero must have a sum of squares that vanishes, and that this condition is equivalent to two conditions on the inner product of the real and imaginary parts of the biquaternion, and the equality of the norms of the real and imaginary parts. We give numerical examples of nilpotents, idempotents and other divisors of zero. Finally, we conclude with a statement about the composition of the set of biquaternion divisors of zero, and its subsets, the idempotents and the nilpotents.