Teemu Roos Ph.D., Senior Researcher Adjunct Professor Helsinki Institute for Information Technology HIIT Exactum building, A322 Department of Computer Science PO Box 68 FI-00014 University of Helsinki Finland teemu.roos at cs.helsinki.fi
16th Jan–30th Apr, 2012: Visiting Fellow Corpus Christi College, University of Cambridge Cambridge, CB2 1RH, UK

What's up?

In January–April 2012, I will be a Visiting Fellow at Corpus Christi College, University of Cambridge.

I'll be a member of the Senior Program Committee of UAI-2012 and an Area Chair at ECML-PKDD 2012.

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

Cambridge, UK, March 2011. Photo: Eira Roos

My traveling/conference schedule in 2012:

• University of Aarhus, January 10.
• University of Cambridge, January 16–April 30.
• ITA-2012, San Diego, February 6–10.
• University of Oxford, March 7–8.
• University of East Anglia, March 22–23.
• Durham University, April 2–5.

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 2010–2011. web pages

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

Teaching

Currently teaching (period I):

• Introduction to Artificial Intelligence (Johdatus tekoälyyn). The language of the course is Finnish.

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).

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

Disclaimer: If you are a student seeking an exchange position, 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.

Research

``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'm a member of the CoSCo research group, the Academy of Finland funded Centre of Excellence COIN, as well as European Union funded Network of Excellence Pascal.

I am also the Programme Manager of the AS (Algorithmic Systems) programme of HIIT.

Some of my work is involved with projects STAM (Algorithmic Methods in Stemmatology) and Modest (Applications of the MDL Principle to Prediction and Model Selection and Testing).

Topics of my interest include

• information theory,
• data analysis (MDL principle, Bayes),
• machine learning.

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

1. T. Roos and Y. Zou, (2011). Analysis of Textual Variation by Latent Tree Structures, to appear in Proc. ICDM-2011, Vancouver.
   
   
2. 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.
   
   
3. T. Pulkkinen, T. Roos, and P. Myllymäki, (2011). Semi-supervised learning for WLAN positioning, to appear in ICANN 2011.
   
   
4. T. Silander, T. Roos, and P. Myllymäki, (2010). Learning locally minimax optimal Bayesian networks, International Journal of Approximate Reasoning (Special Issue on Selected Papers from PGM-2008), in press.   preprint
   
   
5. 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
   
   
6. T. Roos, P. Myllymäki, and J. Rissanen, (2009). MDL denoising revisited, IEEE Trans. Signal Processing, 57:9, 3347–3360.   preprint | supplementary material | C code
   
   
7. 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
   Given a collection of imperfect copies of a textual document, the aim of stemmatology is to reconstruct the history of the text, indicating for each variant the source text from which it was copied. We describe an experiment involving three artificial benchmark data sets to which a number of computer-assisted stemmatology methods were applied. Contrary to earlier similar experiments, we propose and use a numerical criterion to evaluate all the solutions. Moreover, our primary data set is significantly larger than used before. The results suggest the superiority of two computer-assisted methods amongst those tested: the maximum parsimony method implemented in the PAUP* software package and a related compression-based method we have proposed in earlier work.
   
   
8. T. Roos and B. Yu, (2009). Sparse Markov source estimation via transformed Lasso, IEEE Information Theory Workshop (ITW-2009), Volos, Greece, June 10–12.
   
   
9. T. Roos, (2008). Monte Carlo estimation of minimax regret with an application to MDL model selection, IEEE Information Theory Workshop 2008 (ITW-2008), Porto, Portugal, May 5–9.
   
   
10. T. Roos, P. Grünwald, P. Myllymäki, and H. Tirri, (2006). Generalization to unseen cases, in Advances in Neural Information Processing Systems 18 (NIPS-2005), pp. 1129-1136. (An earlier version won the best paper award at BNAIC-2005.)
    
    

Past Events

Cambridge, UK, March 2011. Photo: Eira Roos

My traveling/conference schedule in 2011:

• Studia Stemmatologica IV, University of Cambridge and Microsoft Research, Cambridge, UK, March 21–26.
• BCSMIF-2011 and University of Sao Paulo, Brazil, April 9–17.
• ICANN-2011, Helsinki, June 14–17.
• ISIT-2011, St. Petersburg, Russia, July 31–August 5.
• WITMSE-2011, Helsinki, August 7–10.
• Studia Stemmatologica V, Rome, October 5–8, 2011.
• Nonlinear physics (!), Stockholm, October 18–20, 2011.
• ICDM-2011, Vancouver, December 11–14, 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:

• MIT, Boston, February 8–April 30.
• Columbia University, New York, February 22–23.
• Yale, New Haven, April 1–2.
• Washington University, St. Louis, April 22–23.
• SCAS, Uppsala, Sweden, June 21–23.
• UCLA & UAI-2010, Los Angeles, July 8–11.
• WITMSE-2010, Tampere, Finland, August 16–18.
• Studia Stemmatologica, Pisa, Italy, November 21–24.

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

Pisa, November 2009. Photo: Teemu Roos

My traveling schedule in 2009 (a lot of ITs!):

• ITA-2009, San Diego & HP Labs, Palo Alto, February 8–13.
• ITW-2009, Volos, Greece, June 10–12.
• ISIT-2009, Seoul, Korea, June 28–July 3.
• WITMSE-2009, Tampere, Finland, August 17–19.
• ISTI/CNR & Univ. Pisa, Pisa, Italy, November 5–6.

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. Photo: Teemu Roos

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).

Teaching (TA) in Spring 2007: Three concepts: Utility, Three concepts: Probability, Scientific writing, Personal study plan and teacher tutoring.

During the Spring term 2006, I was a teaching assistant on the Universal AI course by Marcus Hutter (see homework instructions). During the Fall term 2003, I was a teaching assistant on the Graphical Models course by Wray Buntine and Petri Myllymäki. During the Spring term 2002, I was a teaching assistant on the Three Concepts: Information course.

During my postgraduate studies, I visited CWI in Amsterdam for a total of 8 months, in order to collaborate with Prof. Peter Grünwald.

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

Reason

I am married to the loveliest girl in the world, the light of my life, Eira. ''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!

Other

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

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