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Seminars in Combinatorics and Optimization
Algebraic & Enumerative Combinatorics - Santiago Estupiñán
Title: Jeu de Taquin for Mixed Insertion and a Problem of Soojin Cho
| Speaker: | Santiago Estupiñán |
| Affiliation: | University of Waterloo |
| Location: | MC 5417 |
Abstract:
Serrano (2010) introduced the shifted plactic monoid, governing Haiman's (1989) mixed insertion algorithm, as a type B analogue of the classical plactic monoid that connects jeu de taquin of Young tableaux with the Robinson–Schensted–Knuth insertion algorithm. Serrano proposed a corresponding definition of skew shifted plactic Schur functions. Cho (2013) disproved Serrano's conjecture regarding this definition, by showing that the functions do not live in the desired ring and hence cannot provide an algebraic interpretation of tableau rectification or of the corresponding structure coefficients. Cho asked for a new definition with particular properties. We introduce such a definition and prove that it behaves as desired. We also introduce the first jeu de taquin theory that computes mixed insertion. This is joint work with Oliver Pechenik.
There will be a pre-seminar presenting relevant background at the beginning graduate level starting at 1:30pm in MC 5417.
Crypto Reading Group - Youcef Mokrani
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Title: Adaptive Attacks Against FESTA Without Input Validation or Constant-Time Implementation
Abstract: A FESTA trapdoor function is an isogeny-based trapdoor function based on an attempt to apply Kani’s theorem to cryptography. This paper claims that there are adaptive attacks for a FESTA-based scheme if this scheme does not check the correctness of the input matrix or is not implemented in constant time. Our attacks do not apply to the constant-time implementation of the IND-CCA PKE scheme named FESTA proposed in the FESTA original paper. In this paper, we provide adaptive attacks for a FESTA trapdoor function using auxiliary oracles, which reveals the secret key of the function. These oracles may be constructed if the FESTA trapdoor function is used without validating the input matrix or implemented in non-constant time. |
Algebraic & Enumerative Combinatorics - Adrien Segovia-The dimension of semidistributive extremal lattices
| Speaker: | Adrien Segovia |
| Affiliation: | Université du Québec à Montréal |
| Location: | MC 5417 |
Abstract: The order dimension of a partially ordered set (poset), which is often difficult to compute, is a measure of its complexity. Dilworth proved that the dimension of a distributive lattice is the width of its subposet on its join-irreducible elements. We generalize this result by showing that the dimension of a semidistributive extremal lattice is the chromatic number of the complement of its Galois graph (see Section 3.5 of arXiv:2511.18540). We apply this result to prove that the dimension of the lattice of torsion classes of a gentle tree with n vertices is equal to n. No advanced background is required to follow the talk.
There will be a pre-seminar presenting relevant background at the beginning graduate level starting at 1:30pm in MC 5417.