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KTH-CSC-TCS/DDT - Theory Group
Development Plan - 2008-06-22
The theory group (TCS) is a strong research environment. Its mission is to carry the culture of Theoretical Computer
Science, including developing and disseminating new, interesting and useful knowledge in the area. Our judgment is
that our subject area has immediate application interest in computer and information security, and uncertainty
management. But all our research topics have practical relevance on the medium and long terms. A key task of our
group is to pioneer application related fundamental research that can be handed over or split off to more application
dedicated groups, with trained personnel. A showcase example of this is the creation, in 2006, of the bioinformatics
group in the Computational Biology department of CSC.
Professors:
Stefan Arnborg
Johan Håstad
Viggo Kann
Karl Meinke
Associate Professors(docent):
Mads Dam
Henrik Eriksson
Dilian Gurov
Mikael Goldmann
Olof Hagsand
Stefan Nilsson
Lecturers:
Inge Frick
Johan Karlander
Summary of activities 2000-2008
PhD degrees: 13
Licentiate degrees, except as intermediary to PhD: 3
MSc/MScE thesis supervision and examination: 500 theses completed
Mobility:
Jens Lagergren, Lars Arvestad: CSC-TCS-> CSC-CB
Mads Dam, Dilian Gurov: ICT-> CSC-TCS
Olof Hagsand: ICT-> CSC-KTHNOC-> CSC-TCS
Douglas Wikström: SICS->CSC->ETH->CSC-TCS
Excellence center participation:
PSCI, ACCESS, CIAM
Other external funding:
Swedish Science Council, Vinnova, EU FP& and FP7, Saab, Swedish and US defence, SICS
Current Research Areas, in alphabetic order:
Approximation algorithms
Study of provably good algorithms to approximate a solution to a (in general) hard optimization problem. It is generally
useful to study this problem in conjunction with the related problem of showing that an approximation algorithm
cannot, modulo standard complexity-theoretic conjectures, be better than a given one.
Circuit and proof complexity
Involves the study of fundamental questions regarding efficiency in various models of circuit computation and proof
systems. A long-term goal is to find and prove lower bounds on the size of boolean circuits computing given logical
functions. A similar effort is in study of particular proof systems to show that certain propositional tautologies require
long proofs.
Cryptography
Involves the study of fundamental questions regarding existence of provably good cryptographic systems and their
provable properties. Analyses of practical protocols for economic transactions, like digital money, and communication
with information constraints, like voting, auctions, and similar applications, are also done.
Formal methods for computer and information security
This work is both theoretical and practical. The goal is to find implementable procedures to guarantee that computer
systems work according to understandable specifications. A related problem lies in proving that a computer system or
protocol does not leak information. Methods in this area are based in logic, semantics, model theory, probability and
cryptography. Typically, efficient algorithms are essential for making our techniques practical.
Formal testing
Testing of software is traditionally done with intuitively collected and seldom adequate collections of test cases and
accounts for a large fraction of software development cost. Formal testing methods deploy automatically generated test
case collections based on software specification, and instrumentation actual program code. Formal testing is based on
logical or statistical modeling. It is particularly important and promising in distributed systems verification, provided
coverage of the non-deterministic scheduling problem is provided.
Language technology
Involves study and evaluation of efficient and effective methods for language critique, information retrieval, and
building dictionaries. A problem of current interest is using bootstrapping and machine learning for mapping languages
automatically or semi-automatically. This is particularly interesting for minority languages where there are few
language handbooks and a relatively small corpus of available text.
Uncertainty management
Involves the study of general, wellfounded and realistic ways to deal with uncertainty in computer applications. An
important case is to use large amounts of historical and background information in decision making, with applications
in geoinformatics, defense systems (Command and Control), physiology and psychiatry, pharmacology and primary
health care. Whereas goldplating the Bayesian paradigm is still relevant, a challenge is the description of systems
involving intentional agents, leading to interest in game-theoretic approaches.
Future Goals and Focus areas:
In general, the period 200-2008 has been successful, but by the end of the period there were too few doctoral students
and too little research time for faculty. It will be a key concern to improve intramural and external financing and have a
reasonable number of doctoral students in each active research area, preferably also one or more postdoctoral
researchers. A permanent recruitment in distributed algorithms/computing is desirable. The TCS focus areas will be:
Foundational Research:
The TCS department will continue to carry the culture of theory, a core CS topic that is a key to maintain a strong
academic culture and a base for attacking new problems in technology and social development. Efforts will be mainly
be in algorithms and complexity with emphasis on approximation complexity, cryptography and cryptographic
protocols, computer science logic, programming languages, formal testing and uncertainty management.
Distributed Computing, including security, safety and performance:
This is a very promising direction and we already have significant activity in this area including new links between
foundational studies and the security, safety and performance domains. The present model of work in this area assumes
close ties with industrial partners, e.g., in the significant Swedish financial systems software sector, and probably also
with the automatic control discipline.
Complete success in this area will require successful financing and recruitment both on the junior and senior levels.
The outcome of such recruitment will strongly influence the direction of research in this new, almost wide-open field.
One exciting possibility would be to recruit a possibly a senior person in the area of distributed computing. This would
both give an even wider perspective of security and also give us competence in an area that undoubtedly will play a
central role in a future world where computers will be present in essentially any advanced industrial product and the
basic problem will be that of cooperation between such products, the IT infrastructure and users.
Language technology:
The newly proposed Swedish Language Law and the new VR Infrastructure Guide focus on the need of language tools
and language resources for Swedish as well as the Swedish minority languages. We plan to further extend and improve
our work on cost effective methods for developing such tools and resources. As our tradition in this area is strong,
provided that proper funding can be secured, it will be easy to rapidly build up more activities and competence. Such an
effort can, for example, be demonstrated in a citizens’ and residents’ portal for e-Government providing multilingual
support for interaction and advanced case handling with authorities. For this size of demonstrator, cooperation with
linguists and other language technology groups is desirable.