Thu, 03 Nov 2016
17:00
L1

How Can We Understand Our Complex Economy? - Doyne Farmer

Doyne Farmer
(University of Oxford)
Abstract

We are increasingly better at predicting things about our environment. Modern weather forecasts are a lot better than they used to be, and our ability to predict climate change illustrates our better understanding of our effect on our environment. But what about predicting our collective effect on ourselves?  We now use tools like Google maps to predict how long it will take us to drive to work, and other small things, but we fail miserably when it comes to many of the big things. For example, the recent financial crisis cost the world tens of trillions of pounds, yet our ability to forecast, understand and mitigate the next economic crisis is very low. Is this inherently impossible? Or perhaps we are just not going about it the right way? The complex systems approach to economics, which brings in insights from the physical and natural sciences, presents an alternative to standard methods. Doyne will explain what this new approach is and give a few examples of its successes so far. He will then present a vision of the economics of the future which will need to confront the serious problems that the world will soon face.
 

Please email @email to register

Tue, 14 Jun 2016
15:00
L5

Exchanging a key: how hard can it be?

Cas Cremers
(University of Oxford)
Abstract
During the last thirty years, there have been many advances in the development of protocols for
authenticated key exchange. Although signature-based variants of Diffie-Hellman have been
known since the start of this development, dozens of new (two message) protocols are still proposed each
year. In this talk, we present some of the recent history of security definitions for Authenticated Key
Exchange, their many relatives, and discuss strengths and weaknesses. We motivate why there
has been little convergence in terms of protocols or security definitions. I will also present some of our 
recent work in this domain, including new stronger security definitions, and how to achieve them.
Tue, 26 Apr 2016
14:00
L3

Best L1 polynomial approximation

Yuji Nakatsukasa
(University of Oxford)
Abstract

An important observation in compressed sensing is the exact recovery of an l0 minimiser to an underdetermined linear system via the l1 minimiser, given the knowledge that a sparse solution vector exists. Here, we develop a continuous analogue of this observation and show that the best L1 and L0 polynomial approximants of a corrupted function (continuous analogue of sparse vectors) are equivalent. We use this to construct best L1 polynomial approximants of corrupted functions via linear programming. We also present a numerical algorithm for computing best L1 polynomial approximants to general continuous functions, and observe that compared with best L-infinity and L2 polynomial approximants, the best L1 approximants tend to have error functions that are more localized.

Joint work with Alex Townsend (MIT).

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