The second school seminar on 5th November at 2pm, on Teams. If you do not have the Teams link available please contact the organiser, Ian Gent.

**Dimensionality Reduction in non-Euclidean Spaces**

**Richard Connor**

The second school seminar on 5th November at 2pm, on Teams. If you do not have the Teams link available please contact the organiser, Ian Gent.

Deep Learning (ie Convolutional Neural Networks) gives astoundingly good classification over many domains, notably images. Less well known, but perhaps more exciting, are similarity models that can be applied to their inner layers, where there lurk data representations that can give a much more generic notion of similarity. The problem is that these data representations are huge, and so searching a very large space for similar objects is inherently intractable.

If we treat the data as high-dimensional vectors in Euclidean space, then a wealth of approximation techniques is available, most notably dimensionality reduction which can give much smaller forms of the data within acceptable error bounds. However, this data is not inherently a Euclidean space, and there are better ways of measuring similarity using more sophisticated metrics.

The problem now is that existing dimensionality reduction techniques perform analysis over the coordinate space to achieve the size reduction. The more sophisticated metrics give only relative distances and are not amenable to analysis of the coordinates. In this talk, we show a novel technique which uses only the distances among whole objects to achieve a mapping into a low dimensional Euclidean space. As well as being applicable to non-Euclidean metrics, its performance over Euclidean spaces themselves is also interesting.

This is work in progress; anyone interested is more than welcome to collaborate!

- When: 7th April 2020 14:00 - 15:00
- Where: Cole 1.33b
- Series: School Seminar Series
- Format: Seminar

Details TBA.

- When: 17th February 2020 14:00 - 15:00
- Where: Cole 1.33b
- Series: School Seminar Series
- Format: Seminar

**RESCHEDULED: please note the changed date and a non-standard time!**

**Abstract:** Prest is a recently published piece of open-source software for computational revealed preference analysis that provides novel ways to estimate decision makers’ preferences over choice alternatives by analysing their observable choice behaviour. This software is informed by classic as well as recent developments in economic revealed preference theory. Some of the recent developments take the form of models that are computationally complex. This complexity currently hinders the inclusion of these models in the Prest toolkit. The presentation will first aim to describe the primary ideas underpinning Prest and illustrate them with examples from its existing toolkit. It will then proceed with a discussion of some of the challenges pertaining to the expansion of that toolkit with more models and operations. The presentation will be self-contained and no prior background in economics will be necessary.

**Speaker Bio:** Georgios is a Reader in Economics at the University of St Andrews, working mainly on decision theory and revealed preference analysis. In the latter research programme, Georgios’ work aims to improve our understanding of people’s decision processes and preferences through theoretical, experimental/empirical as well as computational methods. Georgios co-developed the Prest software program for computational revealed preference analysis (https://prestsoftware.com/).

- When: 3rd February 2020 11:00 - 12:00
- Where: Cole 1.33a
- Series: SACHI Seminar Series, School Seminar Series
- Format: Seminar

**Abstract:** Innovation and creativity are the research drivers of the Human-Computer Interaction (HCI) community which is currently investing a vast amount of resources in the design and evaluation of “new” user interfaces and interaction techniques, leaving the correct functioning of these interfaces at the discretion of the helpless developers. In the area of formal methods and dependable systems the emphasis is usually put on the correct functioning of the system leaving its usability to secondary-level concerns (if at all addressed). However, designing interactive systems requires blending knowledge from these domains in order to provide operators with enjoyable, usable and dependable systems. The talk will present possible research directions and their benefits for combining several complementary approaches to engineer interactive critical systems. Due to their specificities, addressing this problem requires the definition of methods, notations, processes and tools to go from early informal requirements to deployed and maintained operational interactive systems. The presentation will highlight the benefits of (and the need for) an integrated framework for the iterative design of operators’ procedures and tasks, training material and the interactive system itself. The emphasis will be on interaction techniques specification and validation as their design is usually the main concern of HCI conferences. A specific focus will be on automation that is widely integrated in interactive systems both at interaction techniques level and at application level. Examples will be taken from interactive cockpits on large civil commercial aircrafts (such as the A380), satellite ground segment application and Air Traffic Control workstations.

**Speaker Bio:** Dr. Philippe Palanque is Professor in Computer Science at the University Toulouse 3 “Paul Sabatier” and is head of the Interactive Critical Systems group at the Institut de Recherche en Informatique de Toulouse (IRIT) in France. Since the late 80s he has been working on the development and application of formal description techniques for interactive system. He has worked for more than 10 years on research projects to improve interactive Ground Segment Systems at the Centre National d’Etudes Spatiales (CNES) and is also involved in the development of software architectures and user interface modeling for interactive cockpits in large civil aircraft (funded by Airbus). He was involved in the research network HALA! (Higher Automation Levels in Aviation) funded by SESAR programme which targets at building the future European air traffic management system. The main driver of Philippe’s research over the last 20 years has been to address in an even way Usability, Safety and Dependability in order to build trustable safety critical interactive systems. He is the secretary of the IFIP Working group 13.5 on Resilience, Reliability, Safety and Human Error in System Development, was steering committee chair of the CHI conference series at ACM SIGCHI and chair of the IFIP Technical Committee 13 on Human-Computer Interaction.

- When: 11th February 2020 14:00 - 15:00
- Where: Cole 1.33b
- Series: School Seminar Series
- Format: Seminar

**Abstract: **In this talk, I will present a case study to illustrate how automated algorithm configuration can be used to gain insights into theoretical results on an evolutionary algorithm, namely the (1+(λ,λ)) Genetic Algorithm. This work is a collaboration with Carola Doerr.

The (1+(λ,λ)) Genetic Algorithm is an evolutionary algorithm that has interesting theoretical properties. It is the first algorithm where the benefit of crossover operator is rigorously proved. It is also the first example where self-adjusting parameter choice is proved to outperform any static parameter choice. However, it is not very well understood how the hyper-parameter settings influences the overall performance of the algorithm. Analyzing such multi-dimensional dependencies precisely is at the edge of what running time analysis can offer. In this work, we make a step forward on this question by presenting an in-depth study of the algorithm’s hyper-parameters using techniques in automated algorithm configuration.

**Speaker bio:** Dr Nguyen Dang is a post-doc in the Constraint Programming group at the University of St Andrews. Her main research focus is on automated algorithm configuration, algorithm selection and their applications in various contexts. These techniques make use of statistical methods and machine learning for fine-tuning of algorithm parameters, assessing parameters’ importance and building algorithm portfolios. Another line of her research is about solving combinatorial optimisation problems using metaheuristic algorithms.

- When: 4th February 2020 14:00 - 15:00
- Where: Cole 1.33b
- Series: School Seminar Series
- Format: Seminar

**Abstract:** There is an ever-increasing burden on imaging departments to deliver high-throughput assessment of medical images. MRI in particular provides the advantage of full-body coverage and and a variety of quantitative imaging techniques, such as diffusion-weighted MRI, that can offer potent biomarkers for disease response and prognosis; with the advent of accelerated imaging techniques, many quantitative images can now be acquired in a single patient scan. Increases in computational power and the advent of methodologies such as deep-learning may help to deliver on the promise of truly personalised, image-guided therapies; by helping clinicians to better understand the complexities within multi-parametric MRI it may be possible to derive a non-invasive “digital biopsy” that can be monitored during treatment. In this presentation, we will review recent developments within the Computational Imaging group at the Institute of Cancer Research and Royal Marsden Hospital, demonstrating how novel algorithms and deep learning can be used to assist in the response assessment of advanced prostate cancer and soft-tissue sarcoma.

**Speaker Bio:** Dr Matt Blackledge is the team-leader of computational imaging at the ICR, where he has been developing computational techniques in MRI for over a decade. He is funded by both CRUK and Sarcoma UK to innovate novel approaches to image analysis from MRI and X-ray CT to improve cancer patient outcomes in a variety of disease types. He is particularly interested in how AI can be used to (i) further accelerate MR-image acquisition, (ii) understand cancer heterogeneity in images, and (iii) probe the link between quantitative imaging biomarkers and their underlying biology.

- When: 28th January 2020 14:00 - 15:00
- Where: Cole 1.33b
- Series: School Seminar Series
- Format: Seminar

**Abstract:**

In this talk, I explore how group theory playing a crucial role in cyber security and quantum computation. At the same time, how computer science for example machine learning algorithms and computational complexity could help group theorists to tackle their open problems, as such this could help with cryptanalysis of the proposed primitives.

Symmetry is present in all forms in the natural and biological structures as well as man-made environments. Computational symmetry applies group-theory to create algorithms that model and analyze symmetry in real data set. The use of symmetry groups in optimizing the formulation of signal processing and machine learning algorithms can greatly enhance the impact of these algorithms in many fields of science and engineering where highly complex symmetries exist.

At the same time, Machine Learning techniques could help with solving long standing group theoretic problems. For example, in the paper [J. Gryak (University of Michigan, Data Science Institute), R. Haralick (The City University of New York, the prize recipient of International Association for Pattern Recognition), D. Kahrobaei, Solving the Conjugacy Decision Problem via Machine Learning, Experimental Mathematics, Taylor & Francis (2019)] the authors use machine learning techniques to solve the conjugacy decision problem in a variety of groups. Beyond their utilitarian worth, the developed methods provide the computational group theorist a new digital “sketchpad” with which one can explore the structure of groups and other algebraic objects, and perhaps yielding heretofore unknown mathematical relationships.

Graph theoretic problems have been of interest of theoretical computer scientists for many years, especially the computational complexity problems for such algorithmic problems. Such studies have been fruitful for one of the millennium problems (P vs NP) of the Clay Math Institute. Since graph groups are uniquely defined by a finite simplicial graph and vice versa, it is clear that there is a natural connection between algorithmic graph theoretic problems and group theoretic problems for graph groups. Since the graph theoretic problems have been of central importance in complexity theory, it is natural to consider some of these graph theoretic problems via their equivalent formulation as group theoretic problems about graph groups. The theme of the paper [Algorithmic problems in right-angled Artin groups: Complexity and applications, R. Flores, D. Kahrobaei, T. Koberda, J. of Algebra, Elsevier 2019.] is to convert graph theoretic problems for finite graphs into group theoretic ones for graph groups (a.k.a. right-angled Artin) groups, and to investigate the graph theory algebraically. In doing so, new approaches to resolving problems in complexity theory become apparent. The authors are primarily motivated by the fact that some of these group theoretic problems can be used for cryptographic purposes, such as authentication schemes, secret sharing schemes, and key exchange problems.

In the past couple of decades many groups have been proposed for cryptography, for instance: polycyclic groups for public-key exchanges, digital signatures, secret sharing schemes (Eick, Kahrobaei), hyperbolic groups for private key encryption (Chatterji-Kahrobaei), *p*-groups for multilinear maps (Kahrobaei, Tortora, Tota) among others. [J. Gryak, D. Kahrobaei, The Status of the Polycyclic Group-Based Cryptography: A Survey and Open Problems, Groups Complexity Cryptology, De Gruyter (2016).]

Most of the current cryptosystems are based on number theoretic problems such discrete logarithm problem (DLP) for example Diffie-Hellman key-exchange. Recently there has been some natural connections between algorithmic number theoretic and algorithmic group theoretic problems. For example, it has been shown that for a different subfamily of metabelian groups the conjugacy search problem reduces to the DLP. [J. Gryak, D. Kahrobaei, C. Martinez-Perez, On the conjugacy problem in certain metabelian groups, Glasgow Math. J., Cambridge Univ. Press (2019).]

In August 2015 the National Security Agency (NSA) announced plans to upgrade security standards; the goal is to replace all deployed cryptographic protocols with quantum secure protocols. This transition requires a new security standard to be accepted by the National Institute of Standards and Technology (NIST).

One goal of cryptography, as it relates to complexity theory, is to analyze the complexity assumptions used as the basis for various cryptographic protocols and schemes. A central question is determining how to generate intractible instances of these problems upon which to implement an actual cryptographic scheme. The candidates for these instances must be platforms in which the hardness assumption is still reasonable. Determining if the group-based cryptographic schemes are quantum-safe begins with determining the groups in which these hardness assumptions are invalid in the quantum setting.

In what follows we address the quantum complexity of the Hidden Subgroup Problem (HSP) to determine the groups in which the hardness assumption still stands. The Hidden Subgroup Problem (HSP) asks the following: given a description of a group G and a function f from G to X for some finite set X is guaranteed to be strictly H-periodic, i.e. constant and distinct on left (resp. right) cosets of a subgroup H < G, find a generating set for H.

Group-based cryptography could be shown to be post-quantum if the underlying security problem is NP-complete or unsolvable; firstly, we need to analyze the problem’s equivalence to HSP, then analyze the applicability of Grover’s search problem. [K. Horan, D. Kahrobaei, Hidden Subgroup Problem and Post-quantum Group-based Cryptography, Springer Lecture Notes in Computer Science 10931, 2018].

**Speaker Bio:**

I am currently the Chair of Cyber Security at the University of York, a position I have held since November 2018. While at York, I founded and am the director of the York Interdisciplinary Center for Cyber Security. Before coming to York, I was Full Professor at the City University of New York (CUNY) in New York City. I was at CUNY for 12 years, among other duties, I supervised 7 PhD computer science and mathematics students. In addition to my position at York, I am also an Adjunct Professor of Computer Science at the Center for Cyber Security at New York University (NYU). I have been an adjunct at NYU since 2016. I was a lecturer in Pure Mathematics at the University of St Andrews before New York.

I am an associate editor of the of the Advances of Mathematics of Communication, published by the American Institute of Mathematical Sciences, the chief editor of the International Journal of Computer Mathematics: Computer Systems Theory, Taylor & Francis, and an associate editor of SIAM Journal on Applied Algebra and Geometry, The Society for Industrial and Applied Mathematics. I also have entrepreneurial experience as President and Co-founder of Infoshield, Inc., a computer security company.

My main research area is Post-Quantum Algebraic Cryptography, Information Security, Data Science, Applied Algebra. My research has been supported by grants from the US military: US Office of Naval Research, Canadian New Frontiers in Research Fund Exploration, American Association of Advancement in Sciences, National Science Foundation, National Security Agency, Maastricht-York Investment Fund, Research Foundation of CUNY, London Mathematical Society, the Edinburgh Mathematical Society, Swiss National Foundation, Institut Henri Poincare, and the Association for Women in Mathematics. I have 70 publications in prestigious journals and conference proceedings and several US patents. I have given about 240 invited talks in conferences and seminars around the world.

- When: 19th November 2019 14:00 - 15:00
- Where: Cole 1.33b
- Series: School Seminar Series
- Format: Seminar

**Abstract:**

This talk will demonstrate how model checking based verification of compilers and runtime systems can increase the confidence of parallel execution of programming languages, using two case studies.

As HPC systems continue to increase in scale, their mean time between failure decreases meaning reliability has become a major concern. I will present HdpH-RS, a parallel HPC language. HdpH-RS has a formal semantics, and a fault tolerant work stealing scheduler that has been verified with the SPIN model checker. At embedded scale, program transformations on stateful dynamic code can introduce bugs, race conditions and deadlock. I will present a parallel refactoring tool for the CAL dataflow language. It is integrated with the TINA model checker that we use to identify parallelisable cyclo-static actors in dynamic dataflow programs.

The broader aim of this work is to integrate automated formal verification into parallelising compilers and parallel runtime systems for heterogeneous architectures.

**Speaker bio:** Dr Rob Stewart is an Assistant Professor at Heriot-Watt University. He’s interested in formalising, verifying and implementing dataflow, functional and domain specific programming languages for manycore architectures and programmable hardware.

- When: 12th November 2019 14:00 - 15:00
- Where: Cole 1.33b
- Series: School Seminar Series
- Format: Seminar

**Abstract:** It is well known that older adults continue to lag behind younger adults in terms of their breadth of uptake of digital technologies, amount and quality of engagement in these tools and ability to critically engage with the online world. Can these differences be explained by older adults’ distrust of digital technologies? Is trust, therefore, a critical design consideration for appealing to older adults? In this talk I will argue that while distrust is not, in fact, determinative of non-use and therefore does not explain these differences in tech usage, it is nonetheless key for designers to understand older adult distrust in developing socially responsible technologies.

**Speaker Bio:** Bran is a lecturer in the Data Science Institute at Lancaster University. Her research explores the social impacts of computing, with a particular interest in trust, privacy, and ethics. Her recent work has explored these issues at both ends of the age spectrum, with projects such as IoT4Kids, looking at the privacy, security and ethical issues of enabling children to programme IoT devices; and Mobile Age, looking at developing mobile apps for older adults. Bran currently serves as a member of the ACM Europe Technology Policy Committee.

- When: 5th November 2019 14:00 - 15:00
- Where: Cole 1.33b
- Series: School Seminar Series
- Format: Seminar

**Abstract:**

Two important aspects in hardware design are the safe routing of signals between modules, and ensuring that ports are correctly connected. Well-known hardware description languages such as SystemVerilog, provide nominal checking over these aspects. Thus, leaving correctness checks over module orchestration to be performed post-design-time using static analyses, testing, and during synthesis.

Using a mixture of dependent and quantitative typing, we can lift external correctness checks over module connections directly into the type-system. With this approach we can detect more errors at design time, enhance the safety of our hardware designs, and thus increase design productivity.

In this talk I will introduce and discuss LightClick, an orchestration language for hardware design that exemplifies our approach. LightClick uses quantitative typing to ensure linear usage of ports, and dependent types to ensure that port compatibility is a decidable compile-time check. I will show how LightClick can be used to model simple hardware designs, how SystemVerilog stubs are generated from designs using staged interpretation.

**Speaker Bio:** Jan is a Research Associate at the University of Glasgow, who is interested in using state-of-the-art advances in programming language theory to build more trustworthy systems. Jan is currently involved in the Border Patrol project – a collaboration between the Universities of Heriot-Watt, Glasgow, and Imperial College London to explore how Dependent Typing and Session Typing can help make hardware design safer and secure.