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