Journée-séminaire de combinatoire

(équipe CALIN du LIPN, université Paris-Nord, Villetaneuse)

Le 14 mai 2019 à 14h00 en B107, Sanjay Ramassamy nous parlera de : Extensions of partial cyclic orders, boustrophedons and polytopes

Résumé : While the enumeration of linear extensions of a given poset is a well-studied question, its cyclic counterpart (enumerating extensions to total cyclic orders of a given partial cyclic order) has been subject to very little investigation. In this talk I will introduce some classes of partial cyclic orders for which this enumeration problem is tractable. Some cases require the use of a multidimensional version of the classical boustrophedon construction (a.k.a. Seidel-Entringer-Arnold triangle). The integers arising from these enumerative questions also appear as the normalized volumes of certain polytopes. This is partly joint work with Arvind Ayyer (Indian Institute of Science) and Matthieu Josuat-Verges (Laboratoire d’Informatique Gaspard Monge / CNRS).

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