Eike was invited to give a talk in Kochel

We are glad to inform that Eike Neumann was invited to talk at the Seminar on Computable Topology, which will take place in Kochel, Germany on 13-15 September.

Swansea Theory Group attends the 40th British Colloquium for Theoretical Computer Science

Monika, Faron, Olga, Filippos, Iain and James are attending the 40th British Colloquium for Theoretical Computer Science (BCTCS 2024) hosted by the University of Bath. This year is it also collocated with the 5th Southern and Midlands Logic Seminar. 

Monika has been invited to give a talk on Logic in Railway Verification. Among the other invited speakers are Anupam Das (University of Birmingham), Alex Kavvos (University of Bristol), and Stuart Matthews (Capgemini Engineering).

Upcoming invited talks from our group members

Monika Seisenberger has been invited to give a talk at a joint event of the BCTCS 2024 and Southern Logic Seminar in Bath in April 2024. More information about BCTCS 2024 can be found here.

Arno Pauly will give an invited talk at the Leeds Computability Days in July.

Manlio Valenti will give an invited talk at the AMS-UMI International joint meeting (Palermo, July) and at the joint meeting of the New Zealand, Australian and American mathematical societies (Auckland, December).

 

Giovanni Solda visiting Swansea

Next week Giovanni Solda is visiting us from Ghent. He will give a talk on "A combinatorial principle weak over weak systems yet strong over strong systems".

Abstract:  

Better quasi orders (henceforth bqos) are a strengthening of the notion of well quasi order. Even if their definition is more complicated, the former enjoy nice closure properties that make them, in a way, easier to work with than the latter: this feature made bqos an instrumental tool in proving landmark results like Nash-Williams' theorem and Laver's theorem. From the reverse mathematical point of view, the study of bqos is an interesting area still full of open questions.
In this talk, we will focus on a property of non-bqos, the so-called minimal bad array lemma, and in particular one version of it that we will call MBA − . We will show that MBA − has a very odd behavior when it comes to its reverse-mathematical strength, namely 

• over ATR 0 , MBA − can be seen to be equivalent to the very strong principle of Π 12 -comprehension, yet
• over ACA 0 , MBA − does not imply ATR 0.
In order to prove this result, we will provide a characterization of the quasi-orders that ACA 0 proves to be bqos.

 
This is joint work with Anton Freund, Alberto Marcone, and Fedor Pakhomov.