Séminaire Lotharingien de Combinatoire, 93B.49 (2025), 11 pp.

Enrica Duchi and Gilles Schaeffer

From Order One Catalytic Decompositions to Context-Free Specifications, Bijectively

Abstract. A celebrated result of Bousquet-Mélou and Jehanne (2006) states that the bivariate power series solutions of so-called combinatorial polynomial equations with one catalytic variable (or catalytic equations) are algebraic series. We give a purely combinatorial derivation of this result in the case of order one catalytic equations (those involving only one univariate unknown series). In particular our approach provides a tool to produce context-free specifications or bijections with simple multi-type families of trees for the derivation trees of combinatorial structures that are directly governed by an order one catalytic decomposition.

This provides a simple unified framework to deal with various combinatorial interpretation problems that were solved or raised over the last 50 years since the first such catalytic equation was written by W. T. Tutte in the 60's to enumerate planar maps.


Received: November 15, 2024. Accepted: February 15, 2025. Final version: April 1, 2025.

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