This is the webpage of the UCLan Model Theory Seminar; a regular research seminar run by the Model Theory research group, based in the Jeremiah Horrocks Institute at the University of Central Lancashire.

Everyone is welcome to attend. The seminar is organised by Sylvy Anscombe. Please  contact her  for more details.



Spring 2016

The seminar will run on Mondays between 2pm and 4pm, unless otherwise stated. The location will vary from week to week, so please see each listing below for details. Usually we have lunch before the seminar, and drinks and dinner afterwards. All are welcome!



Autumn 2016

The seminar will run on Mondays between 2pm and 4pm, unless otherwise stated. The location will vary from week to week, so please see each listing below for details. Usually we have lunch before the seminar, and drinks and dinner afterwards. All are welcome!



July 2016

In July 2016, Gareth Boxall is visiting us from Stellenbosch University under the Distinguished Visitors Programme. He will be giving two talks. The first is part of the JHI seminar series, and the second is a Model Theory Seminar.



Summer 2016

The seminar will run on Thursdays between 2pm and 4pm, unless otherwise stated. The location will vary from week to week, so please see each listing below for details. Usually we have lunch before the seminar, and drinks and dinner afterwards. All are welcome!

  • Week 24, Thursday 7th April
  • Li Bingjun, Hunan University of Humanities, Science and Technology
    title: Estrada index of graphs
    abstract:
    time: 2pm-4pm
    location: HB303 (Harris)

  • Week 25, Thursday 14th April
  • Uğur Efem, Oxford
    title: On universal specializations of non-locally modular Zariski geometries
    abstract: Specializations are the key tool in proving the Trichotomy Theorem for Zariski geometries. In this talk I will concentrate on a special class of specializations, called the $\kappa$-universal specializations. The focus of the talk will be on non-locally modular Zariski geometries that only admit $\kappa$-universal specializations. Contrary to the initial intuition this is not the case for all non-locally modular Zariski geometries. I will give some conditions for certain non-locally modular Zariski geometries under which all specializations are $\kappa$-universal. I will also explain how these conditions are related to the conditions given by Serre, under which any principal bundle over an algebraic variety is locally isotrivial.
    time: 2pm-4pm
    location: LE111 (Leighton)

    Our speaker in Week 26 is Jochen Koenigsmann, from Oxford, who is giving two talks. The first talk is to the whole Jeremiah Horrocks Institute, as part of the JHI Seminar series:

  • Week 26, Wednesday 20th April (JHI Seminar)
  • Jochen Koenigsmann, Oxford
    title: On rational numbers
    abstract: "Rational numbers are easier to handle than real numbers because with rationals you can only do algebra, whereas the reals lead you straight into calculus, differential equations, integrals and other tough business." We will contrast this widespread view with the by now well understood phenomenon that the algebra of the reals is much easier than the algebra of the rationals. To illustrate this, we will present two big open problems about the rationals (one along the lines of Hilbert's 10th problem, the other going back to Grothendieck's "anabelian geometry"), explaining very recent progress towards their solution.
    time: 4pm-5pm
    location: LE111 (Leighton)
    The seminar is followed by Cheese and Wine in HB015 (Harris)

    The second talk is part of the UCLan Model Theory Seminar:

  • Week 26, Thursday 21st April
  • Jochen Koenigsmann, Oxford
    title: Back to the model theory of local fields
    abstract: Classical model theory of non-archimedean local fields has regained momentum in recent years. We will highlight some of the new developments on issues of definability and decidability originating from old open problems, but with a view towards new arithmetically compelling challenges.
    time: 2pm-4pm
    location: LE111 (Leighton)

  • Week 27, Thursday 28th April
  • no seminar

  • Week 28, Friday 6th and Saturday 7th April
  • ColloquiumFest 2016
    time: 11am Friday 6th of May - 5.30pm Saturday 7th of May
    location: LE003/LE111 (Leighton), University of Central Lancashire



    Spring 2016

    All seminars will be on Thursdays between 2pm and 4pm. The location will vary from week to week, so please see each listing below for details. We will meet beforehand for lunch from 1pm in the Scholars cafeteria, and all are welcome.

  • Week 18, Thursday 14th January
  • Sylvy Anscombe, UCLan
    title: Henselianity in the language of rings
    abstract: joint work with Franziska Jahnke
    time: 2pm-4pm
    location: LE002

  • Week 19, Wednesday 20th -- Friday 22nd January 2016
  • British Postgraduate Model Theory Conference 2016
    location: Manchester

  • Week 20, Thursday 28th January
  • no seminar

  • Week 21, Thursday 4th February
  • Charlotte Kestner, UCLan
    title: Non-forking formulas in distal NIP theories
    abstract: tba
    time: 2pm-4pm
    location: HB310

  • Week 22, Thursday 11th February
  • Charlotte Kestner, UCLan
    title: Non-forking formulas in distal NIP theories, continued
    abstract: tba
    time: 2pm-4pm
    location: BB142a

  • Week 23, Thursday 18th February
  • Tom Kirk, UCLan
    title: $G$, $G^{0}$, and $G^{00}$
    abstract: I will talk about $G$, $G^{0}$, and $G^{00}$ and explore the action of $G$ on its type space. Then I will discuss these groups in $\mathrm{SO}(2,\mathbb{R})$ and what's known in $\mathrm{SO}(2,\mathbb{Q}_{p})$.
    time: 2pm-4pm
    location: HA135a

  • Week 24, Thursday 25th February
  • Dugald Macpherson, Leeds
    title: Modey Theory of profinite groups
    abstract: I will discuss recent work with Katrin Tent where we consider a profinite group $G$ as a $2$-sorted structure with a second sort which codes (as a uniformly definable family) the system of all open subgroups of $G$. The main theorem is that the theory is $\mathbf{NTP}$ (or just $\mathbf{NTP2}$) if and only if $G$ has an open subgroup which is a direct product of finitely many compact $p$-adic analytic groups (for different primes $p$).
    time: 2pm-4pm
    location: HB310 (Harris)

  • Week 24, Friday 26th February (please note the unusal date and time)
  • Franziska Jahnke, Münster
    title: When does dependence transfer from a field to henselian expansions?
    abstract: Let $K$ be an NIP field and let $v$ be a henselian valuation on $K$. We ask whether $(K,v)$ is NIP as a valued field. By a result of Shelah, we know that if $v$ is externally definable, then $(K,v)$ is NIP. Using the definability of the canonical $p$-henselian valuation, we show that whenever the residue field of $v$ is not separably closed, then $v$ is externally definable. Time permitting, we also discuss the case of separably closed residue fields.
    time: 12pm-2pm
    location: HB010 (Harris)

  • Week 25, Thursday 3rd March
  • Model Theory research group, UCLan
    title: group discussion
    abstract:
    time: 2pm-4pm
    location: HB303 (Harris)

  • Week 26, Thursday 10th March
  • Model Theory research group, UCLan
    title: group discussion
    abstract: tba
    time: 2pm-4pm
    location: FBLT4 (Foster)

  • Week 26, Saturday 12th March
  • Lancashire-Yorkshire Model Theory Seminar
    location: Manchester

  • Week 27, Thursday 17th March
  • Marcus Tressl, Manchester
    title: On Convex valuations of ordered fields
    abstract: I will give a brief introduction to Dedekind cuts of ordered fields and explain how these can be used to understand convex valuations of ordered fields. Further I will show a method to manufacture convex subrings that are definable in a given ordered field. The talk will finish with a few applications to henselian ordered fields. (Parts of this work is joint with Lorna Gregory)
    time: 2pm-4pm
    location: HB303 (Harris)



    Autumn 2015

    All seminars will be on Thursdays between 2pm and 4pm. The location will vary from week to week, so please see each listing below for details. We will meet beforehand for lunch from 1pm in the Scholars cafeteria, and all are welcome.

    Schedule of seminars

  • Week 1, Thursday 17th September
  • Sylvy Anscombe and Lotte Kestner, UCLan
    title: Martin-Pizarro and Pillay's paper `Elliptic and hyperelliptic curves over supersimple fields'
    time: 2pm-4pm
    location: LE303

  • Week 4, Thursday 8th October
  • Charlotte Kestner, UCLan
    title: Introduction to model theory
    time: 2pm-4pm
    location: LH102
    abstract: In this talk I will go over the basics of model theory, starting with a first order theory and touching on the beginnings of stability theory.

  • Week 5, Thursday 15th October
  • David Bradley-Williams, UCLan
    title: Model theory and automorphism groups
    abstract: Continuing with our introductory theme, we will look at some connections between the automorphism group of a model, that is the collection of "symmetries" of a structure, and definability in that model.
    time: 2pm-4pm
    location: HB310

  • Week 6, Thursday 22nd October
  • Lorna Gregory, Manchester
    title: Decidability for theories of modules of tame canonical algebras
    abstract: A long standing conjecture of Mike Prest claims that a finite-dimensional algebra has decidable theory of modules if and only if it is of tame representation type. Up until recently, all known examples of finite-dimensional algebras with decidable theory of modules were of tame domestic representation type. In this seminar, I will talk about how to prove that all tame canonical algebras over algebraically closed fields have decidable theory of modules. Tame canonical algebras are tame non-domestic of linear growth. I will explain in the seminar what the terms tame, domestic and linear growth mean.
    time: 2pm-4pm
    location: GR347

  • Week 7, Thursday 29th October
  • Discussion led by Davide Penazzi, UCLan
    title: Discussion of the model theory of $SL_{2}(\mathbb{R})$
    abstract:
    time: 2pm-4pm
    location: HB159

  • Week 8, Thursday 5th November
  • Charlotte Kestner, UCLan
    title: Introduction to the $p$-adics
    abstract: We give an introduction to the $p$-adics from both an algebraic and model-theoretic point of view.
    time: 2pm-4pm
    location: HB234

  • Week 9, Thursday 12th November
  • break

  • Week 10, Thursday 19th November
  • Gwyneth Harrison-Shermoen, Leeds
    title: Limit Independence
    abstract: Given a large model $M$ of some theory $T$, I will describe a method for lifting well-behaved notions of independence from the theories of substructures of $M$ to a reasonably well-behaved notion of independence in $M$. (In essence, we take the limit of the independence relations in the substructures.) The motivating example - two-sorted theories of infinite-dimensional vector spaces over an algebraically closed field and with a bilinear form - was worked out by N. Granger in his thesis.
    time: 2pm-4pm
    location: HB310

  • Week 11, Thursday 26th November
  • Tom Kirk, UCLan
    title: Subgroups of $\mathrm{SO}(2,\mathbb{Q}_{p})$
    abstract: I will speak about the $p$-adic numbers and subgroups of $\mathrm{SO}(2,\mathbb{Q}_{p})$, as part of the research group's ongoing project. More concretely, we will also discuss the lifting of roots of polynomials using Hensel's Lemma.
    time: 2pm-4pm
    location: HB159

  • Week 12, Thursday 3rd December
  • Franz-Viktor Kuhlmann, University of Silesia, Katowice, Poland
    title: In search of a complete axiomatization for $\mathbb{F}_{p}((t))$
    abstract: I will give a survey of the attempts that have been made since the mid 1960s to find a complete recursive axiomatization of the elementary theory of ${\mathbb F}_p((t))$. This problem is still open, and I will describe the difficulties researchers have met in their search. Some new hope has been generated by Yu. Ershov's observation that ${\mathbb F}_p((t))$ is an "extremal" valued field. However, while his intuition was good, his definition of this notion was flawed. It has been corrected in a paper by Azgin, Kuhlmann and Pop, in which also a partial characterization of extremal fields was given. Further progress has been made in a recent paper, completed in joint work with S. Anscombe. The property of being an "extremal valued field" is both elementary and very natural, so it is an ideal candidate for inclusion in a (hopefully) complete recursive axiomatization for ${\mathbb F}_p((t))$. It implies an axiom scheme that was considered previously, which describes the behaviour of additive polynomials under the valuation. I will discuss why additive polynomials are crucial for the model theory of valued fields of positive characteristic. The open problems around extremal fields provide a good source of research projects of various levels of difficulty for young researchers.
    time: 2pm-4pm
    location: HB234

  • Week 12, Saturday 5th December
  • Lancashire-Yorkshire Model Theory Seminar
    time: all day, beginning with arrival and coffee at 10.30am.
    location: Foster Building, Lecture Theatre 2, UCLan

  • Week 13, Thursday 10th December
  • Davide Penazzi, UCLan
    title: Local and global approaches to the topological dynamics of type spaces
    time: 2pm-4pm
    location: HB234