Discrete mathematical modelling seminar

Seminar information archive ~10/27|Next seminar|Future seminars 10/28~

Organizer(s) Tetsuji Tokihiro, Ralph Willox

2026/11/26

17:00-18:30   Room #118 (Graduate School of Math. Sci. Bldg.)
Mariusz Białecki (Polish Academy of Sciences・Institute of Geophysics)
Catalan-like sequences as limits of a stochastic aggregation-disintegration process (English)
[ Abstract ]
We define a stochastic process using simple, parameter-dependent rules for the aggregation of entities with the possibility of disintegration of the formed clusters and derive the corresponding Smoluchowski-type equations. We show that in the limit of infinite system size, the stationary distribution of cluster sizes is given by a solvable recurrence that, after rescaling, takes the form of a Catalan-like recurrence. This recurrence, for a specific choice of parameters, reproduces various integer sequences, including the Catalan, Motzkin, and Schröder numbers. We also solve the inverse problem, i.e., we show how to determine the values ​​of the process's probability parameters to obtain a recurrence with predetermined coefficients.