News
After too many years, Blazej, Dayoon, Kuba, Pavlo, and Vita finally finished a paper on Kitaoka’s conjecture for real quadratic fields. Combining a careful theoretical work with non-trivial computations, we prove that there are at most 13 real quadratic fields that have a universal ternary quadratic form.
In the beginning of 2025, our group has been extremely active. Magda and Pavlo studied additively indecomposable quadratic forms over totally real number fields, and together with Robin, resolved conjectures of Vukusic and Ziegler about sums of two units. Further, Gordon, Nicolas, Pavlo, and Stevan made a first breakthrough about Pythagoras numbers of rings of integers of infinite algebraic fields.
Jongheun Yoon joined UFOCLAN as our newest postdoc and Stevan Gajovic left for a position at MPIM Bonn.
Selecta Math. published the paper by Gordon and Vita that establishes a new connection between sails, a key notion in the geometric theory of generalized continued fractions, and arithmetic of totally real number fields, specifically, universal quadratic forms and indecomposables.
Vita will give an invited talk at the conference Recent advances in Mathematics and related areas at SRM AP, India, in January 2025. Just like at the previous two editions, there will be many excellent speakers!
Lots of recent progress on universal forms and Northcott property over infinite extensions: With Martin Widmer, we’ve finished a paper showing that they exist only very rarely, and our first paper on the topic was published by JLMS.
Our students were very active and successful in the Student NT Seminar last year: They wrote two papers on the universality of generalized quadratic forms.
Vita was invited to give a talk at the 8th Number Theory Meeting in Torino, Italy.
The Czech Science Foundation is very happy with the progress of UFOCLAN after its first three years. The official evaluation protocol says (modulo corrections of a few minor typos; full text is here): “[…] My general impression is EXTREMELY POSITIVE. Very successful project so far.”
Our number theory friends won two prestigious 4-year Primus grants: Gordon on Automorphic forms for symplectic groups via trace formula, and Martin Čech on Multiple Dirichlet series and analytic number theory (with budgets of ~500,000 USD each).
Nicolas won a 3-year postdoc fellowship from FWO that will fund his work at KU Leuven under the guidance of Raf Cluckers.
Stevan was accepted to a postdoc position at MPIM Bonn from January 2025.
Pavlo and Vita gave invited talks at the 20th N3 days meeting in Tromsø, Norway – even the Sun liked the conference so much that it didn’t set at all!
Four of us (Gordon, Pavlo, Stevan, Vita) are enjoying the 8th Rome Number Theory Symposium.
Martin Widmer has visited us in Prague, mainly for discussions about infinite extensions, Northcott property, and quadratic forms.
Gordon and Vita finished an exciting paper that establishes a new connection between sails, a key notion in the geometric theory of generalized continued fractions, and arithmetic of totally real number fields, specifically, universal quadratic forms and indecomposables.
Pavlo’s and Vita’s recent job call was won by Martin Čech, Subham Roy, and Robin Visser – they will join our team during the Summer.
Dayoon Park, an expert in quadratic lattices and m-gonal forms, joined UFOCLAN as a new postdoc.
Pavlo returned to Prague as the PI of Primus grant Statistical properties of totally real number fields. This prestigious grant will fund him and two postdocs for four years.
We have several new postdoc positions available (supported by Pavlo‘s and Vita’s grants).
Our recent postdoc Daniel Gil Muñoz won a Postdoc Individual Fellowship grant from Czech Science Foundation. It will fund his 2-year stay at University of Pisa, and then 1 further year back with us in Prague.
In the last two months, Stevan gave invited seminar talks at Oxford, Cambridge, Manchester, EPFL, ICMAT Madrid, MPI Leipzig, and Konstanz.
Vita received Dean’s teaching award for excellent student questionnaire results in 2022/23.
Andrew Granville is coming for a research visit: He’ll give a talk in the Mathematical Colloquium on November 9, and in our Number Theory Seminar on November 8.
Vita gave an invited seminar talk at Aalto Uni (Finland) on our recent work (with Gordon and Nicolas) on universal forms and Northcott property. He’ll give a similar talk on October 26 at the online Seminar on Arithmetic Geometry and Algebraic Groups – feel free to attend!
We’re happy to have several guests visiting us this October: Daejun Kim (KIAS), Seok Hyeong Lee (Seoul), Didier Lesesvre (Lille), and Giuliano Romeo (PhD student from Turin).
Stevan was one of the organizers of the successful Conference for Young Number Theorists in Bonn.
Jakub Krásenský defended his PhD thesis on Universal quadratic forms over orders in number fields – and is starting his new job as a tenure track assistant professor at Czech Technical University in Prague, Faculty of Information Technology, Department of Applied Mathematics.
Pavlo Yatsyna received a prestigious Primus grant Statistical properties of totally real number fields which will fund him and several postdocs at our department during 2024 – 2027.
We’re excited about our newest paper (by Gordon, Nicolas, and Vita) that opens up the study of universal quadratic forms over infinite extensions of the rationals. We establish links between the existence of universal forms, the Northcott property, and the square classes of units.
Mentzelos was accepted to a tenure track lecturer position at University of Twente.
Two of our postdocs will soon start their new jobs – Błażej at the Polish Academy of Sciences, and Daniel at the University of Barcelona.
We welcome our newest UFOCLAN team member Leila (age 0).
We had three more visitors in April: Adel Betina, Daniel Kriz, and Anna Rio.
Vita was elected chair of the evaluation panel for mathematics and computer science at Czech Science Foundation.
Karim Becher is visiting us as a guest from Antwerp.
Giacomo Cherubini, our recent postdoc, received the Bolzano Award for his work on Prime geodesic theorem.
In our perhaps best paper so far, Blazej, Pavlo, and Vita proved that real quadratic fields with a universal form of given rank have density zero. This result concludes a part of the story that started eight years ago when Valentin Blomer and Vita constructed the first very sparse sequence of quadratic fields without n-ary universal forms.
Vita wrote a survey paper that gives a (hopefully) accessible overview of our research in the last few years – have a look!
We welcome several new postdocs to our team! Siu Hang “Gordon” Man (already from September 2022), Mentzelos Melistas, Nicolas Daans, and Stevan Gajović (from March 2023).
Magda Tinková received the Josef Hlávka prize for her research conducted during her PhD studies in our group.
Mentzelos Melistas will join us in Prague in January 2023 as the final postdoc hired in our recent job call.
Three guests are visiting us in October: Claire Burrin (ETH Zurich), Pietro Mercuri (La Sapienza, Rome), and Fabien Pazuki (Copenhagen).
Here we are having lunch with Fabien:
Our student Martin Raška, as well as Vita, both received Dean’s teaching award for excellent student questionnaire results in 2021/22. (Martin’s first solo paper also just got accepted by JNT.)
Pavlo’s and Vita’s short paper solving weak Kitaoka’s conjecture and weak lifting problem was accepted by Bulletin LMS.
The winner of the recent job call, Stevan Gajović, accepted our job offer. He should join our team in March 2023 (for 2.5 years).
Vita will give an invited talk at International Conference on Class Groups of Number Fields and Related Topics-2022 in Kerala, India – looking forward to visiting India once again!
Giacomo won a job call for a tenure track position at Sapienza University of Rome where he’ll start around November.
The paper by Jakub and Pavlo on sums of squares of quadratic forms got accepted by Proc. AMS.
Our students Matěj Doležálek and Martin Raška both got the First Prize at the International Mathematics Competition for University Students.
Apply to our new postdoc opening! (Applications should be received ideally by Sep 15.)
Vita will give an invited series of introductory lectures on universal quadratic forms at XXIII International Workshop for Young Mathematicians in Krakow in September.
Giacomo’s and Pavlo’s paper on the potential energy of algebraic integers is accepted by J. Math. Anal. Appl.
The paper by Ester, Jakub, and Martin on Pythagoras numbers in biquadratic fields got accepted by Expositiones Math.
Pavlo will soon start a new postdoc at Aalto University, where he’ll work with Camilla Hollanti.
Matěj Doležálek received the Award of The Learned Society of the Czech Republic for his work Quaternions and universal quadratic forms over number fields.
Dayoon Park is again visiting us for collaboration on universal forms (May & June 2022).
In March we were happy to welcome Bryce Kerr (MPIM Bonn) and Karim Becher (U. Antwerp) as guests.
Siu Hang “Gordon” Man won our job call and will join UFOCLAN as new postdoc!
Magda’s and Vita’s paper on universal forms and indecomposables over the simplest cubic fields was accepted by IMRN.
We welcome Matteo Bordignon as our newest group member! Matteo recently got his PhD in analytic number theory from UNSW Canberra under the supervision of Tim Trudgian.
Jakub and Pavlo proved a new, strong bound on the number of squares of linear forms required to represent all suitable quadratic forms of rank r over a totally real number field. See preprint for this and more at https://arxiv.org/abs/2112.15243.
Ale’s position with us already ended – he’ll soon join the American Institute of Mathematics for his next postdoc.
We have a 3-year postdoc position available! See https://www.mathjobs.org/jobs/list/18130 (deadline is February 15).
Magda Tinková was awarded the prestigious Postdoc Individual Fellowship from Czech Science Foundation, which will provide her with full funding for a 2-year position at Technical University Graz (Austria).
We (Andrew Granville and Ale, Giacomo, Pavlo, Vita) proved that there exist long sequences of consecutive real quadratic fields that all have large class numbers. The preprint is at http://arxiv.org/abs/2111.11549.
Vita gave an invited online talk at the International Conference on Class Groups of Number Fields and Related Topics. Video, slides.
Vita’s habilitation got officially approved and he became docent (associate professor equivalent).
As another guest, we welcome Sudhir Pujahari from Warsaw University (Poland), 10/01-10/16, 2021.
Six new team members are joining UFOCLAN in Fall 2021: postdocs Alessandro, Blazej, Daniel, and Eric, and PhD students Ester and Mikulas!
Our new website is gradually coming alive, thanks to Martina Vaváčková.
Dayoon Park is visiting us as a guest from Ulsan National Institute of Science and Technology (Korea) for 09/01–11/30, 2021.
Magda Tinková defended her PhD thesis “Arithmetic of number fields and generalized continued fractions” and received the best evaluation grade for her GAUK project.
Today, Jasmi joined UFOCLAN as its youngest member (aged 0).
Vita Kala was elected vice chair of the new GACR panel for mathematics and computer science.
UFO was spotted!
