Materiality of Colour: from Neolithic Earth Colours to Contemporary Interference Pigments
Abstract
Artist Antoni Malinowski has been commissioned to produce a major wall painting in the foyer of the new Mathematical Institute in Oxford, the Andrew Wiles Building. To celebrate and introduce that work Antoni and a series of distinguished speakers will demonstrate the different impacts and perceptions of colour produced by the micro-structure of the pigments, from an explanation of the pigments themselves to an examination of how the brain perceives colour.
Speakers:
Jo Volley, Gary Woodley and Malina Busch, the Pigment Timeline Project, Slade School of Fine Art, University College London
‘Pigment Timeline’
Dr. Ruth Siddall - Senior Lecturer in Earth Sciences, University College London
‘Pigments: microstructure and origins?’
Antoni Malinowski
‘Spectrum Materialised’
Prof. Hannah Smithson Associate Professor, Experimental Psychology, University of Oxford and Tutorial Fellow, Pembroke College
‘Colour Perception‘
11.30am, Lecture Theatre 1
Mathematical Institute, University of Oxford
Andrew Wiles Building
Radcliffe Observatory Quarter
No booking required
Quiver Invariant, Abelianisation and Mutation
Abstract
In this talk, gauged quiver quantum mechanics will be analysed for BPS state counting. Despite the wall-crossing phenomenon of those countings, an invariant quantity of quiver itself, dubbed quiver invariant, will be carefully defined for a certain class of abelian quiver theories. After that, to get a handle on nonabelian theories, I will overview the abelianisation and the mutation methods, and will illustrate some of their interesting features through a couple of simple examples.
E11 and Generalised Space-time
Abstract
It has been conjectured that the fundamental theory of strings and branes has an $E_{11}$ symmetry. I will explain how this conjecture leads to a generalised space-time, which is automatically equipped with its own geometry, as well as equations of motion for the fields that live on this generalised space-time.
Lackenby's Trichotomy
Abstract
Expansion, rank gradient and virtual splitting are all concepts of great interest in asymptotic group theory. We discuss a result of Marc Lackenby which demonstrates a surprising relationship between then, and give examples exhibiting different combinations of asymptotic behaviour.
Are resultant methods numerically unstable for multidimensional rootfinding
Abstract
they are competitive practical rootfinders. However, in higher dimensions they are known to be notoriously difficult, if not impossible, to make numerically robust. We will show that the most popular variant based on the Cayley resultant is inherently and spectacularly numerically unstable by a factor that grows exponentially with the dimension. Disastrous. Yet, perhaps, it can be circumnavigated.
Best approximations in Chebfun and applications to digital filters
Abstract
In this talk I will give an overview of the algorithms used by Chebfun to numerically compute polynomial and trigonometric minimax approximations of continuous functions. I'll also present Chebfun's capabilities to compute best approximations on compact subsets of an interval and how these methods can be used to design digital filters.
Krylov methods for operators
Abstract
In this talk we will explore the convergence of Krylov methods when used to solve $Lu = f$ where $L$ is an unbounded linear operator. We will show that for certain problems, methods like Conjugate Gradients and GMRES still converge even though the spectrum of $L$ is unbounded. A theoretical justification for this behavior is given in terms of polynomial approximation on unbounded domains.