Posts | Kaie Kubjas

Exact Solutions in Log-Concave Maximum Likelihood Estimation

Sun, 08 Jan 2023 20:39:50 +0200

Our paper with Alexandros Grosdos, Alexander Heaton, Olga Kuznetsova, Georgy Scholten, and Miruna-Stefana Sorea is now published in Advances in Applied Mathematics. The log-concave maximum likelihood estimate is known to be the exponential of a tent function with the tentpoles being the data points. The tent function induces a subdivision of the convex hull of the data points. It turns out that even determining the optimal subdivision can be challenging! We study the transcendentality of the solutions, give a closed form solution in the simplest case and explore how to certify the solutions.

European Women in Mathematics General Meeting 2022

Sun, 08 Jan 2023 20:01:39 +0200

We organized the European Women in Mathematics General Meeting 2022 at Aalto University during August 22-26, 2022. The conference had 129 participants from 25 countries. The EWM GM 2022 had three lectures by the European Mathematical Society lecturer Claire Voisin and five plenary lectures by Kathrin Bringmann, Maria Bruna, Nina Holden, Kaisa Miettinen, and Ilaria Perugia. There were also 13 minisymposia, a poster session, and an art and math workshop on building origami by Kirsi Peltonen. The gender issues in mathematics were discussed during a panel discussion and women in mathematics were highlighted during Women of Mathematics from Around the World exhibition. Diane Maclagan and Veronica Felli were elected as successors to Andrea Walther and myself to take over the roles of the convenor and deputy convenor of EWM. Many thanks to Karin Baur, Elena Resmerita, Andrea Walther and the local organizing team including Olga Kuznetsova for all the work! The conference was supported by Aalto Science Institute, Federation of Finnish Learned Societies and Foundation Compositio Mathematica.

Applied Algebra Session at the Nordic Congress of Mathematicians

Sun, 08 Jan 2023 19:50:15 +0200

28th Nordic Congress of Mathematicians took place at Aalto University during August 18-21, 2022. Together with Elisenda Feliu (University of Copenhagen) and Cordian Riener (UiT The Arctic University of Norway), we organized the Applied Algebra Session that brought together applied algebraists in the Nordic countries. The list of talks is posted here.

The model-specific Markov embedding problem for symmetric group-based models

Fri, 10 Sep 2021 17:25:27 +0300

Together with my PhD student Muhammad Ardiyansyah and Dimitra Kosta we study the model specific embedding problem for symmetric group-based models in phylogenetics. We provide a characterisation of model embeddable Markov matrices corresponding to symmetric group-based phylogenetic models. Our paper is published in the Journal of Mathematical Biology.

Olga Kuznetsova wins Second Place Poster Award at MEGA 2021

Thu, 10 Jun 2021 00:00:00 +0000

My PhD student Olga Kuznetsova won shared Second Place Poster Award at MEGA 2021 for her poster Algebraic Degree of Optimization Over a Variety. The poster is based on our recent preprint Algebraic degree of optimization over a variety with an application to p-norm distance degree together with Olga Kuznetsova and Luca Sodomaco. Congratulations, Olga!

Distinguishing Level-2 Phylogenetic Networks Using Phylogenetic Invariants

Thu, 29 Apr 2021 00:00:00 +0000

My PhD student Muhammad Ardiyansyah has just posted his first single-authored paper on arXiv. In the paper, he studies the distinguishibility of simple and semisimple level-2 phylogenetic networks extending the earlier work on large-cycle and level-1 networks. Congratulations, Ardi!

Tensor Voices

Wed, 07 Apr 2021 00:00:00 +0000

Eliana Duarte and Thomas Kahle hosted a short podcast on tensors. In one of the five episodes, I give my perspective on tensors. Listen at Tensor Voices website, Apple Podcasts or other podcast apps.

Uniqueness of nonnegative matrix factorizations by rigidity theory

Mon, 01 Feb 2021 00:00:00 +0000

In the joint work with Robert Krone we study the uniqueness of nonnegative matrix factorizations using ideas from the rigidity theory. We give so far the strongest necessary condition for a nonnegative matrix factorization to be unique. Our article has been published in the SIAM Journal of Matrix Analysis and Applications.

Maximum likelihood estimation of toric Fano varieties

Thu, 01 Oct 2020 00:00:00 +0000

In the joint work with Carlos Améndola and Dimitra Kosta we study the maximum likelihood estimation problem for all 2-dimensional Gorenstein toric Fano varieties, we explore the reasons for the ML degree drop and we prove a result about the multiplicativity of ML degrees of codimension zero toric fiber products. This article appeared in the first volume of Algebraic Statistics. This first volume is numbered 11 to honour the past work of the algebraic statistics community.

EWM open letter on COVID-19

Tue, 22 Sep 2020 00:00:00 +0000

European Women in Mathematics published an open letter on the impact of the COVID-19 pandemic. The letter focuses on the impact of the crisis on untenured mathematicians, women and parents. Linked to the letter is also a Resources & Discussion Page.