Increasing Diamonds
نویسندگان
چکیده
A class of diamond-shaped combinatorial structures is studied whose enumerating generating functions satisfy differential equations of the form f2 “ Gpfq, for some function G. In addition to their own interests and being natural extensions of increasing trees, the study of such DAG-structures was motivated by modelling executions of seriesparallel concurrent processes; they may also be used in other digraph contexts having simultaneously a source and a sink, and are closely connected to a few other known combinatorial structures such as trees, cacti and permutations. We explore in this extended abstract the analytic-combinatorial aspect of these structures, as well as the algorithmic issues for efficiently generating random instances.
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