Dr Dmitry Chistikov and Professor Mike Paterson, together with physicists Olga Goulko (Boise State University) and Adrian Kent (Cambridge), have published an interdisciplinary paper Globe-hopping, solving a probabilistic puzzle on the sphere that has applications to quantum information theory.

Suppose a lawn must cover exactly half the area of a sphere. A grasshopper starts from a random position on the lawn and jumps a fixed distance in a random direction. What shape of lawn maximizes the chance that the grasshopper lands back on the lawn? A natural guess would be that a hemispherical lawn is best. It turns out, however, that this is nearly never the case — there are only a few exceptional jump sizes.

This work involving spherical geometry, probability theory, basic number theory, and theoretical physics appears in the Proceedings of the Royal Society A and shows, apart from concern for the well-being of grasshoppers, that there are previously unknown types of Bell inequalities. The Bell inequality, devised by physicist John Stewart Bell in 1964, demonstrated that no combination of classical theories with Einstein's special relativity is able to explain the predictions (and later actual experimental observations) of quantum theory.

A University press release can be found here.

We are pleased to report that members of the department's Theory and Foundations research theme have had 6 papers accepted to the 47th International Colloquium on Automata, Languages and Programming, the main European conference in Theoretical Computer Science and annual meeting of the European Association for Theoretical Computer Science. The papers are:

• On the central levels problem by Petr Gregor, Ondřej Mička and Torsten Mütze
• Matrices of optimal tree-depth and row-invariant parameterized algorithm for integer programming by Timothy Chan, Jacob Cooper, Martin Koutecký, Dan Král and Kristýna Pekárková
• The Complexity of Verifying Loop-free Programs as Differentially Private by Marco Gaboardi, Kobbi Nissim and David Purser
• Rational subsets of Baumslag-Solitar groups by Michaël Cadilhac, Dmitry Chistikov and Georg Zetzsche
• The Strahler number of a parity game by Laure Daviaud, Marcin Jurdzinski and K. S. Thejaswini
• On the power of ordering in linear arithmetic theories by Dmitry Chistikov and Christoph Haase

Another piece of excellent news: Dr Sayan Bhattacharya and Dr Tom Gur have been promoted to Associate Professor, effective from 1 May 2020. Quoting from their recommendations,

Dr Bhattacharya has attracted a very competitive EPSRC New Investigator grant and a high-profile UK-Israel collaborative grant with the Weizmann Institute... . Dr Bhattacharya’s high standing in the research community is confirmed by his memberships of the programme committees of prestigious conferences, as well as his organisation of international research events. … Dr Bhattacharya has developed a new 3rd-year core module for Discrete Mathematics students and delivered it for the past three years, as well as now teaching most of a key 1st-year core module for the same degree course.

and

Dr Gur has attracted a highly prestigious UKRI Future Leaders Fellowship, as well as growing his international leading publications record. He is also growing a successful own research group, having recruited a PhD student and on track to employing several postdocs. … voluntarily exceeding his workload, Dr Gur has developed from scratch and currently teaches a popular 4th-year module on quantum computing. Mentioning here only some of his other contributions, Dr Gur also … is the organiser of the main departmental research seminar, was an active contributor to the department’s recent Athena SWAN submission, and has been developing fruitful links with several industrial partners.

it remains to say many congratulations!