School of Computer Science

PGR Seminar with Zihan Zhang + Berné Nortier

The next PGR seminar is taking place this Friday 4th April at 2PM in JC 1.33a

Below are the Titles and Abstracts for Zihan and Berné’s talks – Please do come along if you are able.

Zihan Zhang

Title: FedOptima: Optimizing Resource Utilization in Federated Learning

Abstract: Federated learning (FL) systems facilitate distributed machine learning across a server and multiple devices. However, FL systems have low resource utilization limiting their practical use in the real world. This inefficiency primarily arises from two types of idle time: (i) task dependency between the server and devices, and (ii) stragglers among heterogeneous devices. We propose FedOptima, a resource-optimized FL system designed to simultaneously minimize both types of idle time; existing systems do not eliminate or reduce both at the same time. FedOptima offloads the training of certain layers of a neural network from a device to server using three innovations. First, devices operate independently of each other using asynchronous aggregation to eliminate straggler effects, and independently of the server by utilizing auxiliary networks to minimize idle time caused by task dependency. Second, the server performs centralized training using a task scheduler that ensures balanced contributions from all devices, improving model accuracy. Third, an efficient memory management mechanism on the server increases scalability of the number of participating devices. Four state-of-the-art offloading-based and asynchronous FL methods are chosen as baselines. Experimental results show that compared to the best results of the baselines on convolutional neural networks and transformers on multiple lab-based testbeds, FedOptima (i) achieves higher or comparable accuracy, (ii) accelerates training by 1.9x to 21.8x, (iii) reduces server and device idle time by up to 93.9% and 81.8%, respectively, and (iv) increases throughput by 1.1x to 2.0x.

Berné Nortier

Title: Shortest paths and optimal transport in higher-order systems

Abstract: One of the defining features of complex networks is the connectivity properties that we observe emerging from local interactions. Nevertheless, not all networks describe interactions which are merely pairwise. Recently, different frameworks for modelling non-dyadic, higher-order, interactions have been proposed, garnering much attention. Of these, hypergraphs have emerged as a versatile and powerful tool to model such higher-order networks. However, the connectivity properties of real-world hypergraphs remain largely understudied. A first, data-driven, work introduces a measure to characterise higher-order connectivity and quantify the relevance of non-dyadic ties for efficient shortest paths in a diverse set of empirical networks with and without temporal information. The analysis presents a nuanced picture.

A second work (in progress) considers higher-order simplicial networks within the context of optimal transport, where shortest paths do not always lead to optimal resource allocation. We extend the existing framework to the higher-order setting to explore to what degree this additional degree of freedom influences the flux of resources in a system of interest.

Distinguished Lecture Series 2025

This years Distinguished Lecture series was delivered yesterday ( Tuesday 1st April) by Professor Arthur Zimek, University of Southern Denmark in Odense, Denmark.

In his talk on, ‘Data Mining and the “Curse of Dimensionality”’ he considered the challenges of the “curse” from the perspective of data mining. In Talk 1, he discussed the “curse” in more detail, identifying relevant aspects or problems. In Talk 2, he considered clustering facing these problems and discussed some strategies and example methods for subspace clustering. In Talk 3, he discussed outlier detection, considering strategies for improved efficiency, effectiveness, and subspace outlier detection.

We are hiring a Professor in Artificial Intelligence

The University of St Andrews wishes to make an appointment to the Johann and Gaynor Rupert Chair in Artificial Intelligence in the School of Computer Science. You will be an outstanding scholar of international standing in Artificial Intelligence with a proven track record of securing significant grant funding and leading high quality externally funded research projects. The successful candidate will be expected to have a range of interests, be able to work across disciplines, and strengthen and complement existing work within the School to make an outstanding contribution to the field’s advancement through research outputs.  You will be expected to represent the University of St Andrews prominently in the UK and international communities

See full advert here: Professor in Artificial Intelligence (Chair) – AC2605LS

PGR Seminar with Joe Loughney

The next PGR seminar is taking place this Friday 28th March at 2PM in JC 1.33a

Below are the Title and Abstract for Joe’s talk – Please do come along if you are able.

Title: Flexible-Order Symmetry Breaking in the Subgraph Isomorphism Problem

Abstract: The Subgraph Isomorphism Problem has many applications, including bioinformatics, computer vision and graph databases. Current state-of-the-art solvers using constraints programming techniques can handle cases with up to 1000 pattern vertices and 10,000 target vertices. We explore various approaches to variable and value symmetry breaking in the problem (and viable strategies to combine the two), implemented in the Glasgow Subgraph Solver, and introduce the notion of ‘flexible ordering’ on symmetry breaking constraints.

Repairing a Commodore PET 4032

Jason Jaques explains the various repairs needed on the Commodore PET 4032 in his YouTube video 

The computer was reported to be exhibiting a troubling screen wobble, an intermittent keyboard, and a broken cassette unit. However, on initial inspection, the unit was actually entirely non-functional. As the machine had been imported from the USA, the computer was expecting a ~117 V, 60 Hz mains supply. When used previously, with a step-down transformer, the screen had shown a significant wobble. Unfortunately, the unit was now entirely dead. Initial exploration indicated that it may have been plugged directly into the UK 240 V 50 Hz supply. Fortunately, while the fuse had been sacrificed, the machine had survived. Once powered up, again with a step-down transformer, the unit’s own power supply was indeed causing significant interference for the built-in display. To resolve the screen wobble, it was eventually decided to replace the transformer with a modern switching power supply. The keyboard suffered from the common hardening of the carbon pads, which made most of the keys inoperable. This was resolved by resurfacing the contacts to restore conductivity. Equally, the cassette unit was brought back to life by a minor repair to an intermittent power connection. Once operational, the unit was “tested” by (among other things) playing a quick round of Satoshi Matsuoka’s Space Invaders, loaded from cassette as demonstrated in this video.

Additional links: Commodore PET Schematics: https://www.zimmers.net/anonftp/pub/c…

Vintage Computer Federation Forums: https://forum.vcfed.org/

MOS 6502 Pinout (by Bill Bertram / Pixel8): https://en.m.wikipedia.org/wiki/File:…

FactSet Talk – Insights into Prompt Engineering 25th March

On Tuesday the 25th of March, FactSet will be visiting the School of Computer Science. They will be doing a talk on Insights into Prompt Engineering, before hosting a networking and recruitment session with pizza. This is taking place in JC1.33 A/B from 3:00pm to 5:00pm. This is a free event to attend for all.

They are recruiting for their paid software engineer externship, paid software engineer internship and graduate software engineer roles. The externship is from the 7th to 19th July in London. This is a two-week program with hands-on experience working with Software Engineering teams. The software engineering summer internship is a 12-week program in summer, with interns joining an existing team at FactSet in London. The graduate program begins in September in London.

Hope to see you all there!

PGR Seminar by Constantine Theocharis + Yigit Yazicilar

The next PGR seminar is taking place this Friday 21st March at 2PM in JC 1.33a

Below are the Titles and Abstracts for Constantine and Yigit’s talks – Please do come along if you are able.

Constantine Theocharis

Title: Efficient Programs with Dependent Types

Abstract:

Dependent types allow us to program using the full power of set theory at our disposal. We can encode conditions of arbitrary complexity, and then show that these conditions are met by our programs, statically. While this paradigm is very effective for verifying systems, often their real-world implementations are done in languages without these verification capabilities, because they produce more efficient programs. In this talk, I will explore some of the main sources of inefficiency in (functional) languages with dependent types, and some work that aims to mitigate these, so that verification and implementation can happen in the same language. A common pattern in these languages is to have ‘refinements’ of data which carry along with them proofs of the properties we care about. The first piece of work is about how to make these refinements true zero-cost abstractions. Another source of inefficiency is that these languages must heap allocate almost everything since the sizes of types cannot always be known at compile time. The second piece of work is about how to keep track of type sizes as part of the type system, so that all heap allocations are explicit and unnecessary for the most part.

Yigit Yazicilar

Title: Automated Nogood-Filtered Fine-Grained Streamlining

Abstract:
We present an automated method to enhance constraint models through fine-grained streamlining, leveraging nogood information from learning solvers. This approach reformulates the streamlining process by filtering streamliners based on nogood data from the SAT solver CaDiCaL. Our method generates candidate streamliners from high-level Essence specifications, constructs a streamliner portfolio using Monte Carlo Tree Search, and applies these to unseen problem instances. The key innovation lies in utilising learnt clauses to guide streamliner filtering, effectively reformulating the original model to focus on areas of high search activity. We demonstrate our approach on the Covering Array Problem, achieving significant speedup compared to the state-of-the-art coarse-grained method. This work not only enhances solver efficiency but also provides new insights into automated model reformulation, with potential applications across a wide range of constraint satisfaction problems.

Fabrizio Capobianco (The Liquid Factory) Speaker on Friday 28th March

Speaker: Fabrizio Capobianco (Partner, The Liquid Factory)

Date: Friday 28th March

Time: 3:00

Venue: Jack Cole 1.33A/B

The Liquid Factory (www.theliquidfactory.com).

At The Liquid Factory, they support the next generation of European entrepreneurs in successfully bridging the gap to Silicon Valley. They achieve this by investing in talent through a 4M EUR fund, which sponsors four Entrepreneurs in Residence each year who temporarily join them in the Italian Alps.

Fabrizio has given talks across Europe sharing his journey as a European entrepreneur who spent 23 years in Silicon Valley before returning to Europe to contribute what he had learned. His presentation also highlights why Silicon Valley remains relevant, though it’s no longer essential for an entire company to be based there. And of course ends with the reasons why he started the Liquid Factory and why it makes sense to apply. These talks typically spark engaging Q&A sessions.

Distinguished Lecture Series: Data Mining and the “Curse of Dimensionality”

Tuesday 1st April

Booth Lecture Theatre, School of Medicine

Schedule:

  • Talk 1: 10:00 – 11:30
  • Lunch: 12:00 – 13:00
  • Talk 2 : 13:00 – 14:30
  • Coffee break: 14:30 – 15:00
  • Talk 3: 15:00 – 16:30

We look forward to welcoming Professor Arthur Zimek, University of Southern Denmark in Odense, Denmark, who will talk about Data Mining and the “Curse of Dimensionality”.

https://en.wikipedia.org/wiki/Arthur_Zimek

Abstract:
While the “curse of dimensionality” is a famous (or rather infamous) phenomenon, it has many different aspects that are not always clearly distinguished, and the impact and relevance of these aspects for some specific task remains often unclear. In this lecture series we consider the challenges of the “curse” from the perspective of data mining. In the first part, we discuss the “curse” in more detail, identifying relevant aspects or problems. In the second part, we consider clustering facing these problems and discuss some strategies and example methods for subspace clustering. In the third and last part, we discuss outlier detection, considering strategies for improved efficiency, effectiveness, and subspace outlier detection.