News archive

Online algebra seminar - May 13th, 1pm PDF Print

We will continue online on Thursday, May 13th, at 13.00 CEST on ZOOM platform (for information how to acces seminar and next programme visit this page) by the talk:

Nathanael Arkor

Higher-order algebraic theories and relative monads

There have traditionally been two ways to reason about universal algebraic structure categorically: via algebraic theories, and via monads. It is well known that the two are tightly related: in particular, there is a correspondence between algebraic theories and a class of monads on the category of sets.

Motivated by the study of simple type theories, Fiore and Mahmoud introduced second-order algebraic theories, which extend classical (first-order) algebraic theories by variable-binding operators, such as the existential quantifier ∃x of first-order logic; the differential operators d/dx analysis; and the λ-abstraction operator of the untyped λ-calculus. Fiore and Mahmoud estab- lished a correspondence between second-order algebraic theories and a second-order equational logic, but did not pursue a general understanding of the categorical structure of second-order algebraic theories. In particular, the possibility of a monad–theory correspondence for second- order algebraic theories was left as an open question.

In this talk, I will present a generalisation of algebraic theories to higher-order structure, in particular subsuming the second-order algebraic theories of Fiore and Mahmoud, and describe a universal property of the category of nth-order algebraic theories. The central result is a correspondence between (n + 1)th-order algebraic theories and a class of relative monads on the category of nth-order algebraic theories, which extends to a monad correspondence subsuming that of the classical setting. Finally, I will discuss how the perspective lent by higher-order algebraic theories sheds new light on the classical monad–theory correspondence.

This is a report on joint work with Dylan McDermott.

Last Updated on Wednesday, 12 May 2021 15:57
Online differential geometry seminar - May 17, 10am PDF Print

The seminar on differential geometry will continue with this lecture:

May 17, 10amonline on MS Teams

Join via this LINK.

Radoslaw Kycia (Masaryk university):

CoPoincare lemma and applications to physics


I will outline the construction of the homotopy operator for codifferential defined on Riemannian manifolds. This notion can be used to solve, in a star-shaped open subset, many equations of mathematical physics including Dirac, Maxwell and string theory problems. I will also present an intriguing correspondence between (co)homotopy operator and Clifford algebra. I will also discuss various incarnations of spinors that appear in the literature. The talk is based on the draft [2] and [1].

[1]Radoslaw Kycia, The Poincare lemma, antiexact forms, and fermionic quantum harmonic oscillator, Results in Mathematics 75, 122 (2020)
[2] Radoslaw Kycia, The Poincare lemma for codifferential, anticoexact forms, and applications to physics, arXiv: 2009.08542 [math.DG]

Last Updated on Wednesday, 12 May 2021 15:54
Online algebra seminar - May 6th, 2pm PDF Print

We will continue online on Thursday, May 6th, the special time of 14.00 CEST on ZOOM platform (for information how to acces seminar and next programme visit this page) by the talk:

Walter Tholen

Spaces vs Categories, Perfect Maps vs Discrete Cofibrations

We consider perfect maps of topological spaces and discrete cofibrations of categories to guide us into Burroni's notions of T-category and T-functor. In that environment we establish a so-called comprehensive factorization system that entails the classical Street-Walters system, as well as the (antiperfect, perfect)-system for continuous maps of Tychonoff spaces known since the 1960s.

(Based on joint work with Leila Yeganeh)

Last Updated on Tuesday, 04 May 2021 10:09
MASH AWARD: Stanislav Sobolevsky PDF Print

MASH AWARD for our department:

Stanislav Sobolevsky, Associate Professor at the New York University, has been awarded the Advanced MASH Belarus Award with his project DIGITAL CITY aimed at building the Digital City Engine and the Urban Network Artificial Intelligence at our department. The project will serve as seed funding for activities in the hot area of Smart Cities, as well as Network Science in general.

MASH AWARD: John Denis Bourke PDF Print

MASH AWARD for our department:

John Denis Bourke has been awarded the MASH Junior Award! Congratulation!

The Masaryk University Award in Sciences and Humanities has been extended  by the junior version. This year, John's award is the only one in the Physical Sciences section. The project will bring essential financial boost to John's research in the coming 3-5 years.

Last Updated on Monday, 03 May 2021 16:44

Page 10 of 49