Séminaire Lotharingien de Combinatoire, B93pref (2025), 1 p.

António Malheiro, Samuel Lopes, Olga Azenhas, André Carvalho, Inês Rodrigues, Diogo Soares, and Gonçalo Varejão

Preface

The 93rd Meeting of the Séminaire Lotharingien de Combinatoire took place from March 23 to 26, 2025, in Pocinho, Portugal, at the High-Performance Rowing Centre (Centro de Alto Rendimento de Remo), located on the banks of the Douro River in Vila Nova de Foz Côa.

This region is truly unique: it is the only Portuguese municipality distinguished by two UNESCO World Heritage recognitions. One for the Côa Valley, celebrated as the largest open-air collection of Paleolithic rock art in the world, and the other for the Upper Douro Wine Region, known for its breathtaking terraced vineyards and the iconic production of Port wine.

This edition featured two outstanding courses: Arvind AYYER (Indian Institute of Science, Bangalore) presented a rich and dynamic series on "The Combinatorics of Multispecies Asymmetric Simple Exclusion Processes," while Nathan WILLIAMS (University of Texas at Dallas) prepared a compelling course on "Coxeter-Catalan Combinatorics." Unfortunately, he had to cancel his presence in the last moment. However, we had the fortune to have Drew ARMSTRONG and Christian STUMP among the participants, who jumped in to brilliantly deliver Williams' lectures.

We had a total of 42 participants and 15 contributed talks, covering a wide range of topics, including enumeration, cyclic sieving of multisets, combinatorial commutative algebra, hyperplane arrangements, partition identities, Rogers-Ramanujan identities, quantum groups, quantum positroids, Lucas analogues, Stokes phenomenon, matroid theory, commuting graphs, Robbins polynomials, Schubert polynomials, Young-Fibonacci Kronecker coefficients, and much more. The breadth and quality of the scientific contributions made this edition particularly stimulating.

The event began with a picturesque journey from Porto on the Douro railway line - a breathtaking route that follows the river through the region's iconic vineyards.

Our stay at the rowing center was not only productive but also socially vibrant. We enjoyed a Port wine tasting session at the venue, visited a local wine cellar, and had a memorable dinner at a restaurant near the Côa Museum.

We warmly thank all the participants for their excellent talks, their enthusiasm, and their contribution to the friendly and collaborative spirit that defines the Séminaire Lotharingien de Combinatoire.

Last, but not least, we express our gratitude to our sponsors. These are on the one hand national funds through FCT - Fundação para a Ciência e a Tecnologia, I.P., under the scope of the projects UIDB/00297/2020 and UIDP/00297/2020 (Center for Mathematics and Applications), UIDB/00144/2020 and UIDP/00144/2020 (CMUP), and UID/00324 (Centro de Matemática da Universidade de Coimbra), and on the other hand the Austrian Science Fund FWF, in the framework of the SFB "Discrete Random Structures: Enumeration and Scaling Limits", grant 10.55776/F1002.

Contributed talks:

Drew ARMSTRONG: Cyclic sieving of multisets with bounded multiplicity and the Frobenius coin problem

Jonathan Gabriel BRADLEY-THRUSH: A combinatorial interpretation of a particular 3φ2 transformation

Shane CHERN: Multiple Rogers--Ramanujan type identities for torus links

Rui DUARTE: Pak-Stanley labeling of hyperplane arrangements

Nathanaël HASSLER: Enumeration of intervals in lattices

João Tomás HIPÓLITO: A method to obtain polynomial generating functions using Lucas analogues

Hans HÖNGESBERG: A Littlewood-type identity for Robbins polynomials

Elena HOSTER: Chow polynomials of uniform matroids

Tomás INÁCIO: Combinatorial applications to the Stokes phenomenon}

Stéphane LAUNOIS: Quantum positroids in quantum Grassmannians

Phillippe NADEAU: Quasisymmetric polynomials revisited

Soichi OKADA: Young-Fibonacci character table

Tánia PAULISTA: Commuting graphs of completely 0-simple semigroups

Michał SZWEJ: A new bijective proof of the cubic q-binomial identity with applications in quantum groups

Gonçalo VAREJÃO: Algebraic invariants of the Eulerian ideal via (T,p)-joins

List of Participants: