Entropies and combinatorics of random branching processes andcontext-free languages
Miller, M.I.; Oapos;Sullivan, J.A.
Information Theory, IEEE Transactions on
Volume 38, Issue 4, Jul 1992 Page(s):1292 - 1310
Digital Object Identifier 10.1109/18.144710
Summary:The entropies and combinatorics of trees that branch according to
fixed but finite numbers of rules are studied. Context-free grammars are
used to categorize the ways in which nodes branch to yield daughter
nodes, thus providing an organized setting to examine the entropies for
random branching processes whose realizations are trees and whose
probabilities are determined by probabilities associated with the
substitution rules of the grammar. Normalized entropy rates H
are derived for the critical branching rate and supercritical branching
rate processes. An equipartition theorem is proved for the supercritical
processes. A strong departure from classical theorems for Markov sources
occurs for supercritical branching processes as the typical sets have
supergeometric growth rates. The combinatorics of the set of all trees
that can be generated from the context-free substitution rules is also
studied
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