Jorma Rissanen

Timeline

1. 1932–1965

   Doctorate in Helsinki

   Born in Pielisjärvi (now Lieksa), Finland, in 1932, he grows up in Kemi, a border town between Finland and Sweden. He earns a master's degree in electrical engineering in 1956 and a licentiate in control theory in 1960 at the Helsinki University of Technology, where Hans Blomberg supervises his Ph.D. on adaptive control theory, completed in 1965.

2. 1960–2002

   Researcher at IBM

   He joins IBM as a researcher in 1960, first in Stockholm while still a doctoral student, and later moves to IBM Almaden in San Jose, California. At IBM Research he works on information theory, estimation and statistical inference. He stays with IBM until his retirement in 2002, apart from a brief stint in 1974 as professor of control theory at Linköping University in Sweden.

3. 1976

   Arithmetic coding at IBM

   In May 1976, his basic algorithms for arithmetic coding, developed at IBM Research, are published alongside independent work by Richard C. Pasco, a Ph.D. student at Stanford University. Arithmetic coding is a form of entropy coding for lossless data compression that encodes an entire message as a single number.

4. 1978

   Minimum description length

   In 1978, he publishes 'Modeling by Shortest Data Description' in Automatica, an MDL learning algorithm built on the statistical notion of information. The idea behind MDL is that the best hypothesis for the regularities in data is the one that compresses the data most. It grows into a rich theory of statistical and machine learning procedures.

5. 1989–2012

   Books on stochastic complexity

   The work on MDL widens into the more general notions of stochastic complexity and universal coding and modeling. He writes Stochastic Complexity in Statistical Inquiry (World Scientific, 1989), Information and Complexity in Statistical Modeling (Springer, 2007) and Optimal Estimation of Parameters (Cambridge University Press, 2012).

6. 1993–1998

   Hamming Medal and Golden Jubilee

   He receives the IEEE Richard W. Hamming Medal in 1993 for fundamental contributions to information theory, statistical inference, control theory, and the theory of complexity. In 1998, the IEEE Information Theory Society gives him a Golden Jubilee Award for Technological Innovation, recognizing his invention of arithmetic coding.

7. 2006–2009

   Kolmogorov Medal and Shannon Award

   In February 2006, he gives the Fourth Annual Kolmogorov Lecture and wins the Kolmogorov Medal of the Computer Learning Research Centre at Royal Holloway, University of London. In 2009, he wins the Shannon Award of the IEEE Information Theory Society.

8. 2020

   Death in Los Gatos

   He dies at his home in Los Gatos, California, in May 2020. At his death he is Visiting Professor at Royal Holloway, University of London, and professor emeritus of Tampere University of Technology.