Extra-Intracellular Transgenetic Algorithm applied to the Graph Coloring Problem

Darwinian evolution has been the most usual metaphor to design evolutionary algorithms. Nevertheless, some researchers criticize the imperfection of the darwinian metaphor in solving several microbiological phenomena and in modelling evolution of species[1]. Genetic Algorithms, GA, introduced by Holland[12], are based on the darwinian paradigm and are successful in finding approximate solutions for many NP-hard problems. However, there are also many cases for which GAs fail. Genetic Algorithms use operators which imitate sexual reproduction to share genes between individuals, generating offspring. Since it implies on interactions between sets of cells, the sexual reproduction is said to be extracellular [4]. In fact, the extracellular paradigm is the main mechanism used by GAs to explore the search space. Though extracellular interactions modify DNA, definitive changes in the DNA may also result from intracellular interactions and from epigenetic rules. Recent researches sho! w ! that genes and culture are inherently linked [14]. Individuals evolve both by anatomical and behavioral selection. Rules that cause anatomical and behavioral elements to come together are called epigenetic. Genes prescribe epigenetic rules, which are the regularities of sensorial perception and mental development that motivate and direct culture acquisition. Culture helps to determine which prescriptive genes survive and multiply from one generation to the next. New well succeeded genes modify the epigenetic rules of the population. The modified epigenetic rules alter the direction and efficiency of the cultural acquisition channels [22]. A meme is an element of a culture that may be considered to be passed on by non-genetic means [16]. Thus, memes are elements of cultural concepts. Richard Dawkins used the term meme to refers to cultural transmission unities in analogy to the role of genes in biological evolution [3]. A meme and a gene have both the dual capacity: carriers of information and creators of behavior. Considering memes and epigenetic rules in evolutionary computation is still a challenge [2]. In the computational context memes were initially associated to exogenous information information out of the extracellular process such as local search in GAs [17]. One of the main contributions of the transgenetic paradigm is that it has means to explore both environmental and cultural dimensions of the evolutionary process. In this paper, a meme is a piece of information, with origins in a specific context, used to rearrange a set or block of genes. To express epigenetic rules in transgenetic algorithms, Computational Transgenetics uses intracellular flow agents called transgenetic agents.