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University of Helsinki Department of Computer Science

Teemu Roos

Ph.D., Assistant Professor

Leader of the Information, Complexity and Learning research group

Department of Computer Science and
Helsinki Institute for Information Technology HIIT
Exactum building, A322
PO Box 68
FI-00014 University of Helsinki

teemu.roos at

What's up?

We will organize the 8th Workshop on Information Theoretic Methods in Science and Engineering (WITMSE) in Copenhagen on 24–26 June 2015. More information to follow soon.

My traveling/conference schedule in 2015:

Since November 2013, following Prof Juho Rousu, I am the host of the Helsinki Distinguished Lecture Series on Future Information Technology.

I have been appointed from 4/2013 onwards as an Assistant Professor (tenure-track) at the Department of Computer Science, University of Helsinki.

In January–April 2012, I was a Visiting Fellow at the University of Cambridge.

Conference and workshop involvement (program committee or equivalent): AISTATS-2011/2014/2015, ECAI-2008, ECML/PKDD-2009/2012, ICDM-2014, IJCAI-2013/2015, NIPS-2014, PGM-2008/2012/2014, S85MC-2011, UAI-2008/2009/2010/2011/2012/2013/2014/2015, WITMSE-2008/2009.


In 2014, I will teach

The 5th Brazilian Conference on Statistical Modelling in Insurance and Finance was held in Maresias, Brazil, on April 10–15, 2011. I gave a two-day short course on MDL. lecture notes | slides (day1) | slides (day2)

I am the instructor of the Undergraduate Research Track (tutkijalinja).

I am currently supervising:

  • Janne Leppä-aho (PhD student)
  • Pedram Daee (PhD student, co-supervised with Prof Sami Kaski)
  • Jussi Määttä (PhD student)
  • Yuan Zou (PhD student)
  • Peter Hedman (MSc student, co-supervised with Prof Petri Myllymäki)
  • Simo Linkola (MSc student)
  • Arttu Modig (MSc student, co-supervised with Prof Jouko Lampinen)
  • Quan Nguyen (MSc student)
  • Olli Orajärvi (MSc student)

Past students:

  • Janne Leppä-aho (MSc, co-supervised with Prof Jukka Corander)
  • Henning Lübbers (MSc, co-supervised with Prof Jyrki Kivinen)
  • Anupam Arohi (MSc)
  • Yuan Zou (MSc)
  • Teemu Pulkkinen (MSc)
  • Toni Merivuori (MSc)
  • Lari Latvala (Msc, co-supervised with Prof Jouko Laasasenaho)

Students interested in MSc/PhD thesis topics related to information theory, statistical modeling, machine learning, artificial intelligence, and digital humanities are welcome to contact me by e-mail (but see disclaimer below).

Disclaimer: If you currently not enrolled at the University of Helsinki, please do not send me e-mail, but contact the Department of Computer Science for information about the application process. Unfortunately I cannot reply to all e-mail inquiries.


``Your act was unwise,'' I exclaimed ``as you see by the outcome.''
He solemnly eyed me. ``When choosing the course of my action,''
said he, ``I had not the outcome to guide me.''
[Ambrose Bierce]

I am the leader of the Information, Complexity and Learning (ICL) research group, which is a part of the CoSCo research group lead by Prof Petri Myllymäki. I'm also affiliated with the Academy of Finland funded Centre of Excellence COIN.

Topics of my interest include

Recent work:

  1. J. Tehrani, Q. Nguyen, and T. Roos, (2015). Oral fairy tale or literary fake? Investigating the origins of Little Red Riding Hood using phylogenetic network analysis, to appear in Digital Scholarship in the Humanities.

  2. Q. Nguyen and T. Roos, (2015). Likelihood-based inference of phylogenetic networks from sequence data by PhyloDAG, to appear in Proc. 2nd International Conference on Algorithms for Computational Biology (AlCoB-2015).

  3. K. Watanabe and T. Roos, (2015). Achievability of asymptotic minimax regret by horizon-dependent and horizon-independent strategies, to appear in JMLR.

  4. J. Määttä, S. Siltanen, and T. Roos, (2014). A fixed-point image denoising algorithm with automatic window selection, in 5th European Workshop on Visual Information Processing (EUVIP-2014).

  5. S. Tasoulis, L. Cheng, N. Välimäki, N. Croucher, S. Harris, W. Hanage, T. Roos, and J. Corander, (2014). Random projection based clustering for population genomics, in IEEE International Conference on Big Data (IEEE BigData-2014).

  6. A. Barron, T. Roos, and K. Watanabe, (2014). Bayesian properties of normalized maximum likelihood and its fast computation, in Proc. IEEE International Symposium on Information Theory (ISIT-2014).

  7. M. Sherman, G. Clark, Y. Yang, S. Sugrim, A. Modig, J. Lindqvist, A. Oulasvirta, and T. Roos, (2014). User-generated free-form gestures for authentication: security and memorability, in Proc. 12th International Conference on Mobile Systems, Applications, and Services (MobiSys-2014).

  8. R. Eggeling, T. Roos, P. Myllymäki, and I. Grosse, (2014). Robust learning of inhomogeneous PMMs, in Proc. 17th Conference on Artificial Intelligence and Statistics (AISTATS-2014).

Selected publications (full list, Google Scholar, DBLP):

  1. K. Watanabe, T. Roos, and P. Myllymäki, (2013). Achievability of asymptotic minimax regret in online and batch prediction, in Proc. 5th Asian Conference on Machine Learning (ACML-2013), JMLR W&CP 29, pp. 181–196.

  2. A. Oulasvirta, T. Roos, A. Modig, and L. Leppänen, (2013). Information capacity of full-body movements, in Proc. 2013 ACM SIGCHI Conference on Human Factors in Computing Systems (CHI-2013), ACM. Best paper honorable mention award.

  3. T. Roos and Y. Zou, (2013). Keep it simple stupid—On the effect of lower-order terms in BIC-like criteria, invited paper in Proc. 2013 Information Theory and Applications Workshop, (ITA-2013).

  4. T. Roos and Y. Zou, (2011). Analysis of textual variation by latent tree structures, in Proc. 2011 International Conference on Data Mining (ICDM-2011), IEEE Press, pp. 567–576.

  5. A. Carvalho, T. Roos, A. Oliveira, and P. Myllymäki, (2011). Discriminative learning of Bayesian networks via factorized conditional log-likelihood, JMLR 12(Jul):2181–2210.

  6. T. Pulkkinen, T. Roos, and P. Myllymäki, (2011). Semi-supervised learning for WLAN positioning, in Proc. ICANN 2011, Lecture Notes in Computer Science 6791–6792, Springer, pp. 355–362.

  7. T. Silander, T. Roos, and P. Myllymäki, (2010). Learning locally minimax optimal Bayesian networks, International Journal of Approximate Reasoning 51(5):544–557.   preprint

  8. J. Rissanen, T. Roos, and P. Myllymäki, (2010). Model selection by sequentially normalized least squares, Journal of Multivariate Analysis 101:4, 839–849.   preprint | R code

  9. T. Roos, P. Myllymäki, and J. Rissanen, (2009). MDL denoising revisited, IEEE Transactions on Signal Processing, 57:9, 3347–3360.   preprint | supplementary material | C code

  10. T. Roos and T. Heikkilä, (2009). Evaluating methods for computer-assisted stemmatology using artificial benchmark data sets, Literary and Linguistic Computing, 24:4, 417–433, doi:10.1093/llc/fqp002. abstract | data-sets

Past Events

I am a member of the organizing committee of the 11th Conference of the European Society for Textual Scholarship (ESTS-2014). The conference will be held in Helsinki on Oct 30-Nov 1, 2014.

We organized the 7th Workshop on Information Theoretic Methods in Science and Engineering (WITMSE) in Hawaii on July 5-8, 2014, right after the ISIT symposium. website

Starting in October 2013, I was a Fellow of the Finnish Institute in Rome (Villa Lante).

Associated with our CHI-2013 paper, we are lauching a web server for computing the information capacity from your own motion capture data: Please ask for a beta testing account.

My traveling/conference schedule in 2014:

I was a co-chair of WITMSE-2013 in Tokyo, Japan, August 26–29.

My traveling/conference schedule in 2013:

Our paper "Information capacity of full-body movements" gets a Best Paper Honorable Mention Award at CHI-2013. If you are planning to attend the conference, please visit our fun interactive Kinect-based demo!

Special issue on selected papers from PGM-2010 in the International Journal of Approximate Reasoning (editors Roos, Myllymäki, Jaakkola): link to editorial and articles.

I served as a member of the Senior Program Committee of UAI-2012 and an Area Chair at ECML-PKDD 2012.

I was an external evaluator at the PhD thesis defense of Thomas Toftkjær at Aarhus University on January 10, 2012.

My traveling/conference schedule in 2012:

The Academy of Finland Centre of Excellence COIN starts in 1/2012.

We organized the 4th Workshop on Information Theoretic Methods in Science and Engineering in Helsinki, on August 7–10, 2011, right after ISIT 2011. web pages

Tuomas Heikkilä, Petri Myllymäki and I organize a series of stemmatology workshops in Helsinki and elsewhere in 2010–2012. web pages

Cambridge, UK, March 2011.
My traveling/conference schedule in 2011:

4/2011: I was conferred the title Adjunct Professor (in Finnish, dosentti) by the Faculty of Science, and appointed as a senior reseacher at HIIT.

I was invited to the senior program committee of UAI-2011.

The Academy of Finland has graciously decided to fund me under a postdoctoral researcher's project.

Petri Myllymäki, Tommi Jaakkola, and I were the program committee co-chairs of the 5th European Workshop on Probabilistic Graphical Models (PGM-2010) in Helsinki, September 13–15, 2010. web pages

In February–April 2010, I visited Prof. Tommi Jaakkola's group at MIT, Boston.

My traveling schedule in 2010:

I got the ERCIM (European Research Consortium for Informatics and Mathematics) 2009 Cor Baayen Award.

Pisa, November 2009.
My traveling schedule in 2009 (a lot of ITs!):

In Fall 2009, I lectured the new course Information-Theoretic Modeling (4 cr) and Information-Theoretic Modeling Project (2 cr).

The University of Helsinki has granted funding to project STAM (Algorithmic Methods in Stemmatology) for the years 2009–2011. project website | "Computer programs can do wonders"

The Finnish Cultural Foundation has awarded a Science Workshop grant (EUR 200,000) on stemmatology for the years 2009–2010. announcement (w/ fanfares) (in Finnish)

As of August 2008, I have been appointed as post-doctoral researcher at HIIT for three years.

Berkeley, April 2008.
In January–April 2008, I visited UC Berkeley (Prof. Bin Yu's group) and ICSI.

During the Fall term 2007 I lectured the Three Concepts: Information course.

I defended my Ph.D. thesis "Statistical and Information-Theoretic Methods for Data Analysis" on June 9, 2007. The opponent was Prof. Alon Orlitsky (UCSD). Pre-examiners were Prof. Ioan Tabus (Tampere UT) and Prof. Tommi Jaakkola (MIT). electronic version (summary part).

I received a Ph.D. degree (in Computer Science) from the University of Helsinki in 2007. I was supported by HeCSE (Helsinki Graduate School in Computer Science and Engineering). My supervisors were Prof. Henry Tirri (on industrial leave), and Prof. Petri Myllymäki. In addition to computer science I have minors in mathematics and philosophy (see a list of finished courses).

Earlier, I have done some work on mobile device positioning. For scientific publications, see list of publications. For working products, go to Ekahau.


I am married to the loveliest girl in the world, the light of my life. ''You are the reason I am. You are all my reasons.''

Since July 31st 2003, the universe revolves around a boy. Since March 1st 2007, we have two boys!


Take a look at (old) Cosco papers visualized using the Similarity Metric of Vitányi and Cilibrasi and multidimensional scaling (Sammon mapping).

Play a game of Rock, Paper, Scissors: rock beats scissors, paper beats rock, and scissors beat paper. Even such a simple game offers some theoretically interesting problems: Can one predict the other player's choice? What is the best strategy against a good opponent? (Yes, the computer could cheat, but I promise it doesn't.) Such questions were considered by Claude Shannon in the 1950s; see a modern variation of his 'Mind-Reading Machine' based on data-compression (CTW).

Choose one: Your choice: My choice: You Me Draw

Last updated on April 17, 2015