Author Archives: OP

Meeting to commemorate the logician Erik Palmgren (1963-2019) on the occasion of the World Logic Day

We meet to remember the great logician Erik Palmgren who sadly passed away in November 2019 .

To honor Erik Palmgren’s work, Anton Setzer will give a talk with the title:

Palmgren’s interpretation of inductive definitions in type theory and development of  higher type universes in type theory.

The meeting also marks the 2nd World Logic Day.

Venue: Theory Lab (CoFo 209)

Time: 14th of January 2020, 2-3 pm

Hideki Tsuiki is back in Swansea

We Hideki Tsuiki in Swanseaare glad to welcome Hideki Tsuiki in Swansea again.  This Thursday we really enjoyed his talk on “Imaginary Cubes —  Mathematics, Puzzle, Art and Education”.

Abstract: Imaginary cubes are three-dimensional objects with square projections in three orthogonal ways just as a cube has.   How many different kinds of imaginary cubes can you imagine?  In this talk we  show that there are 16 kinds of minimal convex imaginary cubes which includes regular tetrahedron, cuboctahedron, and two objects that we call H and T.  As we will explain, H and T have a lot of beautiful mathematical properties related to tiling, fractal, and higher-dimensional geometry, and based on these properties, the speaker has designed a puzzle, constructed three-dimensional math-art objects, and used them for educations at various levels from elemental school to graduate schools. In this talk, I will explain mathematics of imaginary cubes and show the activities I have been engaged in.  I will carry a couple of copies of the puzzle and some of the math-art objects so that the audience can enjoy them while I am staying in Swansea.

2nd Proof Society Workshop on Proof Theory and its Applications

Following the Summer School, we are really proud to host the 2nd Proof Society Workshop. The workshop was an opportunity to listen to a lot of interesting invited and contributed talks on proof theory and various areas of its application:

Adam Wyner: Computational Law – The Case of Autonomous Vehicles
Yong Cheng: Exploring the incompleteness phenomenon
Matthias Baaz: Towards a Proof Theory for Henkin Quantifiers
Sonia Marin: On cut-elimination for non-wellfounded proofs: the case of PDL
Gilles Dowek: Logical frameworks, reverse mathematics, and formal proofs translation
Benjamin Ralph: What is a combinatorial proof system?
William Stirton: Ordinal assignments correlated with notions of reduction
Oliver Kullmann: Practical proof theory: practical versions of Extended Resolution
Anton Setzer and Ulrich Berger on behalf of Ralph Matthes: Martin Hofmann’s case for non-strictly positive data types – reloaded
Laura Crosilla: Philosophy of mathematics and proof theory
Takako Nemoto: Recursion Theory in Constructive Mathematics
Arno Pauly: Combinatorial principles equivalent to weak induction
Antonina Kolokolova: The proof complexity of reasoning over richer domains
Joost Joosten: The reduction property revisited
Helmut Schwichtenberg: Computational content of proofs

Thanks to all the speaker and participants and we hope to see you all again soon.

Proof Society Workshop 2019

Summer School: Day 4

Congratulations to Iris van der Giessen for winning the best poster competition and special thanks to Andreas Weiermann for the beautiful picture of Wales that serves as our main prize.

Big thanks to all the speakers and the participants for joining our Summer School. We hope to see you again during the future events by the Proof Society.

Proof Society Summer School 2019

Summer School: Day 2 and 3

We were glad to welcome Takako Nemoto, who joined us on the second day of the Summer School and gave her course on Reverse Mathematics.

As a treat, the participants of the Summer School had a trip to Rhossili and enjoyed a walk along the Welsh coastal path with stunning views. Big thanks to Arved Friedemann and Melissa Antonnelli for the beautiful photos.

Proof Society Summer School

We are very glad to welcome all the participants of the 2nd International Summer School on Proof Theory.

The first day began with a lecture on Universal Proof Theory by Rosalie Iemhoff, followed by Wolfram Pohlers‘ talk on Ordinal Analysis, Bounded Arithmetic lecture from our own Arnold Beckmann, introduction to Proof Mining by Paulo Oliva, Paola Bruscoli’s talk on Structural Proof Theory and Anton Setzer’s lecture on MLTT.

We were lucky with both the lovely weather and the fact that Bay Campus is located right at the seafront, so the evening brought a nice treat for everyone in a form of a BBQ at the beach. Big thanks to Arnold, Faron for their grilling and Ulrich, Rosalie, Monika, Arved, Aled, Anton, Olga and everyone else who helped with the organisation.

Faron BBQ

Federico Cerutti visiting

Federico Cerutti from Cardiff University is visiting us this Thursday. He will give a talk on Probabilistic Logic Programming with Beta-Distributed Random Variables.

Abstract: We enable aProbLog—a probabilistic logical programming approach—to reason in presence of uncertain probabilities represented as Beta-distributed random variables. We achieve the same performance of state-of-the-art algorithms for highly specified and engineered domains, while simultaneously we maintain the flexibility offered by aProbLog in handling complex relational domains.
Our motivation is that faithfully capturing the distribution of probabilities is necessary to compute an expected utility for effective decision making under uncertainty: unfortunately, these probability distributions can be highly uncertain due to sparse data. To understand and accurately manipulate such probability distributions we need a well-defined theoretical framework that is provided by the Beta distribution, which specifies a distribution of probabilities representing all the possible values of a probability when the exact value is unknown.

Philipp Schlicht visiting

Philipp Schlicht is visiting us today from Bristol. He’ll give us an introduction to automatic structures in the theory seminar today (2pm, CoFo 201).

Abstract: Automatic structures were first studied by Khoussainov and Nerode in 1995. I will first give an introduction with a focus on automatic ordinals and groups and then talk about tree-automatic structures. In particular, I will mention some recent partial results with Jain, Khoussainov and Stephan on the isomorphism problem for tree-automatic ordinals.