Abstract:
|
We study the long time evolution of a large data structure
while inserting new items.
It is implemented using a well
known computer science approach based on 2-3 trees.
We have seen self-organized critical behavior on this data structure.
To tackle this problem we have introduced and
studied experimentally three statistical magnitudes: the stress of a
tree, the sequence of jump points and the distribution of subtrees
inside a tree.
The stress measures the amount of free space inside the 2-3 tree. When
the stress increases some part of the tree is restructured in a way
close to an avalanche. Experimentally we obtain a potential law for
stress distribution. When the tree does not have more free space in
any internal node, needs to grow up. When this happens, the height of
the whole tree increases by one and we have a jump
point. Experimentally these points have good expected behavior.A 2-3
tree is composed from a great number of other 2-3 trees called their
subtrees. We have studied experimentally the distribution of the
different subtrees inside the tree.
Finally we analyze these results using simple theoretical models
based on fringe analysis, Markov and branching processes.
These models give us a quite good description of the long term
process. |