Computer Science » FoCS Archive News - Before Sept 20

Grasshopper jumping on a sphere gives new quantum insights

Thu, 27 Aug 2020 14:32:00 GMT

Members of the FoCS group, 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.

Oxford-��TV Complexity Meetings

Mon, 15 Jun 2020 22:15:00 GMT

We are excited to announce a new series of meetings on complexity theory jointly organised by Oxford and ��TV.

Meetings take place online and consist of informal talks dedicated to topics of interest in computational complexity theory and related areas. Our goal is for these meetings to serve as a forum for discussion and quick dissemination of results. Note that meetings will not be recorded, and anyone interested in complexity theory is welcome to join.

Information about speakers and talks, as well as information about joining the mailing list, can be found at this link: Oxford-��TV Complexity Meetings.

We are looking forward to seeing you at the next talk!

Six papers accepted to the 47th ICALP

Tue, 21 Apr 2020 22:44:00 GMT

Another ICALP is coming, and another good performance of the FoCS group: 6 papers from our group has been 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:

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

Dr Sayan Bhattacharya and Dr Tom Gur promoted to Associate Professor

Tue, 21 Apr 2020 22:26:00 GMT

Two of our rising stars, Dr Sayan Bhattacharya and Dr Tom Gur, have been promoted to Associate Professor, effective from 1 May 2020. Sayan has made several fundamental contributions in the area of dynamic graph algorithms and has recently attracted an EPSRC New Investigator grant. Tom has been actively working in complexity theory and quantum algorithms, and has recently attracted a highly prestigious UKRI Future Leaders Fellowship.

Dr Alexander Kozachinskiy joins the FoCS group

Tue, 21 Apr 2020 22:19:00 GMT

Dr Alexander Kozachinskiy has joined the department to work as a Research Fellow on the "Solving Parity Games in Theory and Practice" project. He will be working with Dr Marcin Jurdzinski and Prof Ranko Lazic.

Alexander received a PhD degree in Mathematics from the Lomonosov Moscow State University. His thesis is devoted to communication complexity and its connections to other topics in Computational Complexity Theory. Two of Alexander's papers won the Best Student Paper Awards' at the CSR 2016 and CSR 2018 conferences. Before joining the University of ��TV he has also worked as Junior Research Fellow at the Faculty of Computer Science of the Higher School of Economics in Moscow.

Welcome new theory PhD students

Sun, 27 Oct 2019 22:05:00 GMT

We welcome four new theory PhD students who have joined the Department this fall (from left to right on the picture):

Thejaswini K S (advisor: Marcin Jurdzinski)
Mary Scott (advisor: Graham Cormode)
Marcel de Sena Dall Angol (advisor: Tom Gur)
Sam Coy (advisor: Artur Czumaj)

Dr. Igor Carboni Oliveira joins the FoCS group and the department as a new Assistant Professor

Wed, 09 Oct 2019 11:31:00 GMT

The FoCS group and the Department of Computer Science are welcoming our new Assistant Professor, Dr. Igor Carboni Oliveira, who will be associated with the Division of Theory and Foundations (FoCS) and the Centre for Discrete Mathematics and its Applications (DIMAP).

Before joining ��TV, Igor held postdoctoral positions at the Department of Computer Science at the University of Oxford and at the School of Mathematics at Charles University in Prague, and was a research fellow at UC Berkeley's Simons Institute for the Theory of Computing. He obtained his PhD in Computer Science from Columbia University in 2015. He is also Royal Society University Research Fellow 2019.

His research is primarily focused on the limitations of algorithms and computations, with connections to combinatorics and mathematical logic. For more information about his work and interests, please see his web page at https://www.dcs.warwick.ac.uk/~igorcarb/

EPSRC funding success for Dr Sayan Bhattacharya

Fri, 04 Oct 2019 18:52:46 GMT

We are pleased to report that Dr Sayan Bhattacharya from the Theory and Foundations research theme at the Computer Science Department has received an EPSRC New Investigator Award. This will allow him to lead a research project on the theory and applications of dynamic algorithms. The approximately £250K project will aim to develop new techniques to design algorithms for fundamental optimisation problems in a setting where the input data changes over time.

The proposal was ranked top at its funding prioritisation panel, and the reviewers said:

The intended research explorations are of very high quality and will likely make a substantial impact on the research community; and possibly on the industrial sector.

Cryptography Meets Algorithms at the AlgoUK Workshop

Tue, 01 Oct 2019 09:37:00 GMT

The Foundations of Computer Science Research Group (FoCS) recently hosted world-renowned researchers in the areas of cryptography and algorithms at the AlgoUK workshop. The event, held on September 17-18 2019, attracted over 130 participants.

Adi Shamir (Weizman Institute), co-inventor of public key cryptography and Turing Award winner, talked about his recent work on understanding the fragile behaviour of machine learning systems. Madhu Sudan (Harvard), winner of the Nevanlinna and Gödel awards, talked about new constructions of "polarizing" codes for communication. Svetla Nikova (KU Leuven) talked about recent work on achieving security against powerful adversaries.

Other speakers at the two day event were Adrià Gascon (Google/The Alan Turing Institute), Mary Cryan (Edinburgh), Paul Goldberg (Oxford), Christian Ikenmeyer (Liverpool), Christian Konrad (Bristol), Daniel Paulusma (Durham) and Thomas Sauerwald (Cambridge).

Slides and abstracts for the talks are available at the workshop website, https://algouk.wixsite.com/warwick2019.

Seven papers accepted to the 31st SODA

Wed, 25 Sep 2019 16:56:21 GMT

We are pleased to report that members of the department's Theory and Foundations research theme have had 7 papers accepted to the 31st Annual ACM-SIAM Symposium on Discrete Algorithms, to be held in Salt Lake City, Utah, USA, January 5-8, 2019. SODA is the premier international conference on algorithms research, and the papers are:

Parameterized Complexity and Approximability of Directed Odd Cycle Transversal by M. S. Ramanujan, Daniel Lokshtanov, Saket Saurabh, Meirav Zehavi
An Improved Algorithm for Incremental Cycle Detection and Topological Ordering in Sparse Graphs by Sayan Bhattacharya, Janardhan Kulkarni
Coarse-Grained Complexity for Dynamic Algorithms by Sayan Bhattacharya, Danupon Nanongkai, Thatchaphol Saranurak
Combinatorial Generation via Permutation Languages by Elizabeth Hartung, Hung P. Hoang, Torsten Mütze, Aaron Williams
On the Power of Relaxed Local Decoding Algorithms by Tom Gur, Oded Lachish
Relaxed Locally Correctable Codes with Nearly-Linear Block Length and Constant Query Complexity by Alessandro Chiesa, Tom Gur, Igor Shinkar
Sublinear time approximation of the cost of a metric k-nearest neighbor graph by Artur Czumaj, Christian Sohler