In spite of the COVID-19 outbreak, we are glad to host BCTCS 2020 starting today, even if virtually. For more information on invited and contributed talks, check the official BCTCS 2020 website.

# Category Archives: Research

# 25th International Workshop on Algebraic Development Techniques 2020

Today Swansea is hosting the first virtual WADT, and you are gently invited to participate.

The virtual WADT is part of the 25th International Workshop on Algebraic Development Techniques 2020, which hopefully will still happen as a physical meeting in autumn this year. The algebraic approach to system specification encompasses many aspects of the formal design of software systems. Originally born as a formal method for reasoning about abstract data types, it now covers new specification frameworks and programming paradigms (such as object-oriented, aspect oriented, agent-oriented, logic and higher-order functional programming) as well as a wide range of application areas (including information systems, concurrent, distributed and mobile systems).

The workshop takes place under the auspices of IFIP WG 1.3.

Please see below for the programme.

# Seminar series on Computability Theory and its Applications

Our colleague Arno Pauly is on the Programme Committee of the Computability Theory and its Applications seminar series, which currently is taking place virtually.

The seminar now has a YouTube channel where you can find the recordings of past talks you may have missed. The information on future talks, the timings of those, and the links to the videos are all available on the webpage here:

# Yoruki Yamagata’s talk on Falsification of Cyber-Physical Systems Using Deep Reinforcement Learning

**Due to COVID-19 outbreak across the world, we need to move our theory seminars online to ZOOM.** We are staying on track with the schedule and **Yoriyuki Yamagata** will give his talk tomorrow at 2pm.

Topic:* Falsification of Cyber-Physical Systems Using Deep Reinforcement Learning.*

Abstract: “Falsification” is a method to find a system input or parameter (counter-example) which causes a behavior violating a given specification (usually given by metric or signal temporal logic). Because the correctness of a complex CPS is difficult to be proven, falsification is more practical approach than full verification. A counter-example found by falsification can be used for debugging and testing. Failure of falsification does not generally mean the correctness of the system, but suggests it in some degree. “Robustness guided falsification” is an approach of falsification. “Robustness” is a numerical measure of how robustly a formula holds. If robustness becomes negative, the formula is false. Therefore, minimizing robustness can lead falsification of a formula.

In this talk, we introduce a method to recast robustness guided falsification to a “reinforcement learning problem”. Reinforcement learning is a machine learning technique in which an agent finds a law of an interacting environment and maximizes a reward. We implement our method using “deep reinforcement leaning”, in which deep neural networks are used, and present a case study to explore its effectiveness. (This work is a collaboration with Shuang Liu, Takumi Akazaki, Yihai Duan, Jianye Hao)

# Update on BCTCS2020

We remain hopeful that our conference will go ahead as planned. However, due to the uncertainty created by COVID-19, we are putting into place contingency plans.

Swansea University has procured a licence for a robust video-conferencing system (ZOOM) which we can use for the conference. If it becomes necessary, then a user would need to install this onto their computer. This system is free to install and use, the only cost is for Swansea as the licence holder. Of course, the computer would need to be connected to a webcam and microphone in order to participate fully in the conference – in particular, to deliver a lecture or to ask questions of the speakers.

Anyone who cannot come to Swansea due to the COVID-19 situation would have their fee reimbursed through eventbrite (as you won’t be requiring the catering). However, we really don’t want this to be an incentive to stay home; AlgoUK/BCTCS is first and foremost a net working event, so if it is possible, we are keen to welcome you in person.

We will keep you aware of any developments, and thank you for your patience and understanding as we do our best to ensure AlgoUK/BCTCS is as successful as it can be.

# 2nd World Logic Day

Today as a part of the 2nd World Logic Day our Theory group commemorated the work of Erik Palmgren (1963-2019), who sadly passed away last year.

Anton Setzer presented Erik’s most influential papers, which had a big impact on Anton’s own research.

# 36th British Colloquium for Theoretical Computer Science

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Swansea University is looking forward to host BCTCS2020 this April.

# 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 are 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.