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Recombination Example

An interesting observation that illustrates the role of mutations is that the observed organization we have called ``level 3'' occurred as a result of one single crossover operation. In this lucky event (fig. 2.31), the bottom half part was reused to create also the top half part, discarding all the previous evolution of a top half that did not create a branching structure.

The ``branches'' organization proved to be evolutionarily more robust than the ``fork'' organization found initially, as it survived until the end of the run. The reuse of subparts and submodules is fundamental to generate these type of discrete transition.

  
Figure 2.31: Recombination. An interesting example of a recombination at the highest level, that creates a recursive structure. The two parents (top) are close relatives, very similar. The root parent (top left) got the crossover point in the trunk of the structure; bricks colored white were discarded by the operation. The secondary parent (top right) had its insertion point at the root. The resulting structure is shown at the bottom. Besides the bricks lost by the root parent's replacement of a subtree, other bricks were lost during the development process: the secondary parent lost all its top bricks (colored white) because they became out-of-bounds, and the central-left branch of the root parent lost three bricks because the maximum bricks limit (127) was reached. The final version of the tree (fig. 2.30) evolved from this individual.

\resizebox*{0.47\textwidth}{!}{\includegraphics{lego/graph/legodad.eps}} \resizebox*{0.47\textwidth}{!}{\includegraphics{lego/graph/legomom.eps}}

\resizebox*{0.6\textwidth}{!}{\includegraphics{lego/graph/legoson.eps}}



next up previous
Next: Discovery is creativity: EvoCAD Up: Symmetry, Branching, Modularity: Lego Previous: Symmetry, Branching, Modularity: Lego
Pablo Funes
2001-05-08