In memoriam Alex S. Fraser [1923-2002]

T HE EVOLUTIONARY computation community lost one of its pioneers on July 14, 2002, when Alex S. Fraser passed away as a result of complications from a heart attack. Fraser was one of the first to conceive and execute computer simulations of genetic systems, and his efforts in the 1950s and 1960s had a profound impact on computational models of evolutionary systems. The simulation algorithms he used were important not only in the simulation of genetical problems, but provided a menu of techniques that enriched the entire simulation effort in any problem that involved probability sampling among a population of alternatives, the heart of Monte Carlo methods. Fraser was born in London, U.K., and lived in Hong Kong for most of his youth; however, he studied at the University of New Zealand, and later went to the University of Edinburgh, and subsequently to the Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Sydney, Australia. It was at the CSIRO where Fraser made his seminal contributions to evolutionary computation. Following the construction of the ILLIAC computer at the University of Chicago, CSIRO designed and built their own version, called the SILLIAC, and Fraser began using it to simulate genetic selection processes. Beginning with [1], Fraser embarked on a comprehensive series of simulations of evolutionary processes [2]–[13], and encouraged and collaborated with others on many related publications in this series [14]–[18]. Fraser published extensively in the Australian Journal of Biological Sciences , and his efforts influenced colleagues in evolutionary biology significantly [19]–[21]. Fraser’s first efforts [1], published in 1957, studied the case of diploid organisms represented by binary strings of a given length, say . Each bit in a string represented an allele (either dominant or recessive) and the phenotype of each organism was determined by its genetic composition. Reproduction was accomplished using an-point crossover operator where each position along an organism’s genetic string was assigned a proba-