1 Lineage Selection

Lineage selection is implemented as an additional step to bias selection toward different lineages from the initial population. To perform selection, individuals are placed into groups based on common genetic lineages. Tournament selection picks individuals by first picking a random genetic lineage and then a random individual from within that lineage. A tournament is held between these random individuals. Each genetic lineage has an equal change of contributing an individual to each tournament. The method introduces no elitism or no direct measure of size, shape, content, or fitness. The aim of lineage selection is to maintain diversity so that the population contains good individuals that are not just diverse.

Figure 5.2 shows an example of lineage selection, which can be described as follows:

1. Select a random lineage $k$ from $1\ldots L$, where $L$ is the total number of unique lineages in the current population,
2. Select from lineage $k$, which consists of individuals $i\ldots j$, a random individual, where $j-i \geq 1$,
3. Repeat steps 1 and 2 above to produce $T$ individuals for a tournament of size $T$.

Thus, a tournament consists of random individuals from random lineages.