Homepage of Peter Harremoës (Entro-Peter)

Peter
                  Harremoes


E-mail:

Telephone: +45 39 56 41 71

Skype: peterharremoes

Private address:
Rønne Alle 1, st.
DK-2860
Søborg

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Research

My research is centred around information theory. Information theory was developed to optimize communication between humans but the relevant concepts have much wider applications. A main goal of my research is to tie information theory closer together with probability theory, statistics, and physics.

List of Publications

I have made a BibTeX file with a lot of items related to information theory.

Bayesian networks

I have worked on the relation between Bayesian networks and irreversibility, and my ultimate goal is to build a bridge between these ideas and information theory. For a longer period I have been working on the idea of using lattice theory to describe Bayesian networks. This approach will also lead to new non-Shannon inequalities. I have some unpublished results on this already.

Convergence theorems in probability

The second law of thermodynamics states that the entropy of a closed system increases to its maximum. Most of the major convergence theorems in probability theory can be stated in a similar fasion or related fasion. These information theoretic convergence theorems are typically stronger that what one finds int he traditional literature in that they give convergence in information rather than convergence in total variation. I have published results on central limit theorem, law of large numbers, law of small numbers, law of thin numbers, martingale and reversed martingale convergence, Markov chains and ergodicity. some result on law of iterated logarithms are still to be published.

Inequalities

Convergence is controled by inequalities and information theoretic problems often boil down to inequalities. I have in particular worked on the use of topology, new plotting techniques and interval arithmetics.

Statistics

The link between information theory and statistics has been known for a long time, but the research area is still very active and new results are found all the time. One idea is to use ideas from information theory to analyse problems of traditional statistical inference. The asymptotic efficiency of various test statistics can be analyzed and the main result is that the likelihood ratio statistic (based on information divergence/KL-divergence) is more Bahadur efficient than other statistics. At the moment I am working on extimates of the tail probabiblities of likelihood ratio statistic.

Game theory

The theory of combinatorial games like board games and the theory of social games with Nash-equilibria are normally considered as separate theories. Nevertheless the two theories can be combined by considering social games where the payoff function has combinatorial games as values rather than money.

Quantum theory

The statistical aspects of quantum theory are quite challanging. One way of viewing this field is that it is a theory dominated by symmetries. Actually a lot of the results that are normally formulated in the framwork of Hilbert spaces can be formulated as results on spaces with certain symmetries.

Entropy logo

Editorial work

I am associate editor the journal Entropy (until recently I was Editor-in-Chief). This is a free online journal that publishes articles about entropy and related concepts, and their numerous applications. I also have an editorial page with some extra material.

I serve as reviewer of numerous other journals including: Mathematical Reviews, IEEE Trans. Inform. Theory, Physica A, JIPAM,  and many others. I am also on the board of the society of Danish science editors.

Events

ISIT 2010 Austin in Texas, 13.-18. June, 2010. Presentation1. Presentation2.
JETC 11 Joint European Thermodynamics Conference took place from 27 June till 1 July 2011 in Chemnitz, Germany.
Information Geometry and its Applications Leipzig, 2.-6. August 2010.
Prague Stochastics Praha, 30. August - 3. September, 2010.
Igor Vajda Memorial Colloquium 12-13 November 2010 Prague.
SigmaPhi2011 Cyprus 11-15 July 2011.
ISIT 2011 July, 31 - August, 5, 2011, in Saint Petersburg. I will be in charge of the recent result session at this event.
Witmse2011 Helsinki 7-10 August.
ISIT 2012 Cambridge, MA, USA, 1-6 July 2012.
ITW 2012 Lausanne 3-7 Sept. 2012.

Some of my other pages

Turnpage This page describes various fact about the constant tau. The page also exists as PDF
Teaching page At this page I collect various material of relevance for math teaching.

Other links

Information Theory Society This is part of IEEE, which I am member of. The page has a lot of useful links related to information theory.
Danish Climbing Federation I am active climber and has served as president of this organization.
Danske VidenskabsRedaktører Home page for the society of  Danish Scientific Editors. I am on the board of this society.
Entropy The journal of which I was Editor-in-Chief.
Ideal scientific equipment A less useful link.
Minimum Description Length on the web This pages is devoted to MDL and its applications. I contains links to articles and people working in the field.
Pi is Wrong! Page by Robert Palais advocating for having a symbol for 2 π.
Rational trigonometry Everybody who is teaching trigonometry should know the excellent new contribution to this field by Norman Wilderberger. He demonstrates that squared Euclidean distance (quadrance as he call it) should play a more active role in all trigonometry. This is good new for all researchers in rate distortion theory and statistics.
The cross entropy method
Tau Manifesto Page that describes the advantage of using tau as a symbol for 2 π. I have also made a centiturn protractor that is useful when measuring angles in terms of turns and centiturns. It is convenient for making pie charts.

Nice software

TpX Nice Windows program for making figures for LaTeX documents. The program can generate PGF and TikZ code. Freeware.
MikTeX This is my favorite LaTeX distribution.
R General program mostly used for statistics. Freeware.
GeoGebra The program is intended for making mathematical figures. The program was mainly made for educational purposes, but it becomes more and more advanced and useful. It can generate TikZ code. Freeware.
LyX User interface that makes it easy and fast to generate LaTeX code. Freeware.
Maple This is my favorite software for more advanced calculations. There exist a lot of pachages htat extends the functionality of the program. Not freeware, nor at all!
Scientific Workplace User interface for generating LaTeX code and doing scientific calculations. Appearently the program is not developed anymore, but it is still possible to get excellent technical support.
JabRef This is an advanced Java program to edit your BibTeX database.

Some collegues

Flemming Topsøe
Oliver Johnson
Ioannis Kontoyiannis
Christophe Vignat
Peter Grünwald
Lukasz Debowski
Gábor Tusnády
Lászlo Györfi
Tim van Erven
Petr Jizba