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Andersson, K. (2014). Exact Probability Distribution versus Entropy. Entropy, 16(10), 5198-5210
Open this publication in new window or tab >>Exact Probability Distribution versus Entropy
2014 (English)In: Entropy, ISSN 1099-4300, E-ISSN 1099-4300, Vol. 16, no 10, p. 5198-5210Article in journal (Refereed) Published
Abstract [en]

The problem addressed concerns the determination of the average numberof successive attempts of guessing a word of a certain length consisting of letters withgiven probabilities of occurrence. Both first- and second-order approximations to a naturallanguage are considered. The guessing strategy used is guessing words in decreasing orderof probability. When word and alphabet sizes are large, approximations are necessary inorder to estimate the number of guesses. Several kinds of approximations are discusseddemonstrating moderate requirements regarding both memory and central processing unit(CPU) time. When considering realistic sizes of alphabets and words (100), the numberof guesses can be estimated within minutes with reasonable accuracy (a few percent) andmay therefore constitute an alternative to, e.g., various entropy expressions. For manyprobability distributions, the density of the logarithm of probability products is close to anormal distribution. For those cases, it is possible to derive an analytical expression for theaverage number of guesses. The proportion of guesses needed on average compared to thetotal number decreases almost exponentially with the word length. The leading term in anasymptotic expansion can be used to estimate the number of guesses for large word lengths.Comparisons with analytical lower bounds and entropy expressions are also provided.

Place, publisher, year, edition, pages
Basel, Switzerland: MDPI AG, 2014
Keywords
information entropy, security, guessing
National Category
Computer Sciences
Research subject
Computer Science
Identifiers
urn:nbn:se:kau:diva-34247 (URN)10.3390/e16105198 (DOI)000344459500003 ()
Available from: 2014-10-09 Created: 2014-10-09 Last updated: 2018-01-11Bibliographically approved
Andersson, K. (2012). Numerical Evaluation of the Average Number of Successive Guesses. In: Jérôme Durand-Lose, Natasa Jonoska (Ed.), Unconventional Computation and Natural Computation: 11th International Conference, UCNC 2012, Orléans, France, September 3-7, 2012, Proceedings. Paper presented at 11th International Conference, UCNC 2012 Orléans, France, September 3-7, 2012 (pp. 234-234). Berlin Heidelberg: Springer
Open this publication in new window or tab >>Numerical Evaluation of the Average Number of Successive Guesses
2012 (English)In: Unconventional Computation and Natural Computation: 11th International Conference, UCNC 2012, Orléans, France, September 3-7, 2012, Proceedings / [ed] Jérôme Durand-Lose, Natasa Jonoska, Berlin Heidelberg: Springer , 2012, p. 234-234Conference paper, Poster (with or without abstract) (Refereed)
Place, publisher, year, edition, pages
Berlin Heidelberg: Springer, 2012
Series
Lecture Notes in Computer Science, ISSN 0302-9743 ; 7445
National Category
Computer and Information Sciences
Research subject
Computer Science
Identifiers
urn:nbn:se:kau:diva-26666 (URN)978-3-642-32893-0 (ISBN)
Conference
11th International Conference, UCNC 2012 Orléans, France, September 3-7, 2012
Available from: 2013-03-18 Created: 2013-03-18 Last updated: 2018-01-11Bibliographically approved
Andersson, K. (2006). Vad är kunskap?. Kapet, nummer 1, 1
Open this publication in new window or tab >>Vad är kunskap?
2006 (Swedish)In: Kapet, nummer 1, Vol. 1Article in journal (Other (popular science, discussion, etc.))
Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2006
Identifiers
urn:nbn:se:kau:diva-25410 (URN)
Available from: 2013-01-22 Created: 2013-01-22 Last updated: 2014-10-13
Andersson, K. (2005). Cellular Automata. In: Bubenko, Janis (Ed.), Promote IT 2005: proceedings of the fifth Conference for the Promotion of Research in IT at New Universities and University Colleges in Sweden : Borlänge, Sweden 11-13 May, 2005. Paper presented at Conference for the Promotion of Research in IT at New Universities and University Colleges in Sweden : Borlänge, Sweden 11-13 May, 2005 (pp. 21-30). Lund: Studentlitteratur
Open this publication in new window or tab >>Cellular Automata
2005 (English)In: Promote IT 2005: proceedings of the fifth Conference for the Promotion of Research in IT at New Universities and University Colleges in Sweden : Borlänge, Sweden 11-13 May, 2005 / [ed] Bubenko, Janis, Lund: Studentlitteratur , 2005, p. 21-30Conference paper, Published paper (Refereed)
Abstract [en]

Cellular automata have a widespread use in the description of complex phenomena in disciplines as disparate as for example physics and economics. They are described by a lattice of cells, states of the cells, and rules for updating the states of the cells. One characteristics of a cellular automaton is the simplicity of the rules that determine how the cellular automaton evolves in time. These rules are local, are applied in parallel to all the cells and despite their simplicity they may give rise to a complex macroscopic behaviour. In this paper this is illustrated by examples from hydrodynamics and it is shown that cellular automata might provide powerful alternatives to partial differential equations

Place, publisher, year, edition, pages
Lund: Studentlitteratur, 2005
Series
Conference for the Promotion of Research in IT at New Universities and University Colleges in Sweden ; 5:2005 Borlänge
National Category
Computer and Information Sciences
Research subject
Computer Science
Identifiers
urn:nbn:se:kau:diva-17597 (URN)91-44-03875-5 (ISBN)
Conference
Conference for the Promotion of Research in IT at New Universities and University Colleges in Sweden : Borlänge, Sweden 11-13 May, 2005
Available from: 2013-01-21 Created: 2013-01-21 Last updated: 2018-01-11Bibliographically approved
Andersson, K. (2005). Cellular Automata in Science.
Open this publication in new window or tab >>Cellular Automata in Science
2005 (English)Other (Other (popular science, discussion, etc.))
Abstract [en]

Cellular automata have a widespread use in the description of complex phenomena in disciplines as disparate as, for example, physics and economics. A cellular automaton is a lattice of cells, and the cells can be in a finite number of states. By using simple local rules the states of the cells are updated in parallel at discrete time steps. In short, a cellular automaton can be characterised by the three words - simple, local, and parallel. These three words are one of the reasons for the attractiveness of cellular automata. They are simple to implement and they are well suited for parallel computers (computations). Another reason for using cellular automata are for their spatio-temporal properties. The lattice may represent space and the updating of the cells gives a

dimension of time.



In spite of the simplicity of cellular automata they may give rise to a complex macroscopic behaviour. This is illustrated, in this thesis, by an hydrodynamic example, namely the creation of vortices in flow behind a cylinder.



Although cellular automata have the ability to describe complex phenomena it is sometimes hard to find the proper rules for a given macroscopic behaviour. One approach which has been successfully employed is to let cellular automata rules evolve (for example, through genetic algorithms) when finding the desired properties. In this thesis this is demonstrated for two-dimensional cellular automata with two possible states of the cells. A genetic algorithm is used to find rules that evolve a given initial configuration of the cells to another given configuration.

Keywords
Cellular automata, complex phenomena, genetic algorithms
Identifiers
urn:nbn:se:kau:diva-17601 (URN)
Available from: 2013-01-21 Created: 2013-01-21 Last updated: 2014-10-13
Andersson, K. (2004). Cellular Automata. In: Bubenko, Janis (Ed.), Promote IT 2004: proceedings of the fourth Conference for the Promotion of Research in IT at New Universities and University Colleges in Sweden : 5-7 May, 2004, Karlstad University, Sweden. P. 1. Paper presented at Promote IT 2004, Karlstad, Sweden, May 5-7, 2004 (pp. 598-608). Karlstad: Karlstad University Press, 2004:26
Open this publication in new window or tab >>Cellular Automata
2004 (English)In: Promote IT 2004: proceedings of the fourth Conference for the Promotion of Research in IT at New Universities and University Colleges in Sweden : 5-7 May, 2004, Karlstad University, Sweden. P. 1 / [ed] Bubenko, Janis, Karlstad: Karlstad University Press , 2004, Vol. 2004:26, p. 598-608Conference paper, Published paper (Refereed)
Abstract [en]

In this paper properties and behavior of cellular automata are considered. Cellular automata can simply be described as lattices of cells, where the cells can be in a finite number of states. By using simple rules the states of the cells are updated in parallel at discrete time steps. Depending on the rule and, to a certain degree, the initial states of the cells, the evolution of a cellular automaton is restricted to a small number a ways. Some cellular automata evolve uniformly, meaning that all cells end up in the same state, while others evolve randomly, meaning that the states of the cells appear to be totally randomized during evolution. Intermediate behavior, displaying repetitiveness or nesting, also occurs.Properties of cellular automata that are discussed in the paper are, for instance, sensitivity to initial conditions, randomness, reversibility, entropy, and conservation. These properties also appear in the physical world and cellular automata provide good examples in the understanding of these properties.The evolution of cellular automata can be used for computations. Some cellular automata even display the property of universality, a term well known from the universal Turing machine, meaning that there is no limit to the sophistication of the computations they can perform.

Place, publisher, year, edition, pages
Karlstad: Karlstad University Press, 2004
Series
Karlstad University Studies, ISSN 1403-8099
Keywords
Cellular automata
National Category
Computer and Information Sciences
Research subject
Computer Science
Identifiers
urn:nbn:se:kau:diva-17599 (URN)9185019933 (ISBN)
Conference
Promote IT 2004, Karlstad, Sweden, May 5-7, 2004
Available from: 2013-01-21 Created: 2013-01-21 Last updated: 2018-01-11Bibliographically approved
Andersson, K. (2003). Cellular Automata. Karlstad
Open this publication in new window or tab >>Cellular Automata
2003 (English)Other (Other (popular science, discussion, etc.))
Abstract [en]

Properties and behavior of cellular automata are considered. Cellular automata can simply be described as lattices of cells, where the cells can be in a finite number of states. By using simple rules the states of the cells are updated at discrete time steps. The evolution of cellular automata can be used for computations. Some cellular automata display universality meaning that there is no limit to the sophistication of the computations they can perform.

Place, publisher, year, pages
Karlstad: , 2003
Keywords
Cellular automata
Identifiers
urn:nbn:se:kau:diva-17600 (URN)
Available from: 2013-01-21 Created: 2013-01-21 Last updated: 2014-10-13
Andersson, K. (2003). The electronic spectrum of VCr. Theoretical Chemistry Accounts, volume 110, number 3
Open this publication in new window or tab >>The electronic spectrum of VCr
2003 (English)In: Theoretical Chemistry Accounts, volume 110, number 3Article in journal (Refereed)
Abstract [en]

The electronic spectrum of VCr has been studied using the complete-active-space self-consistent field complete-active-space second-order perturbation theory approach. Potential energy curves for 12 electronic states have been computed. Transition energies, with respect to the X^2Delta ground state, for some of the calculated electronic states are (with possible experimental values within parentheses): 0.53 eV (0.56) for A^2Sigma+, 1.03 eV (1.14) for A^4Delta, 1.20 eV (1.14) for B^2Delta, 1.45 eV (1.51) for B^4Delta, 1.60 eV (1.51, 1.78) for C^2Delta, and 1.61 eV (1.63) for A^4Sigma^-.

Place, publisher, year, edition, pages
Heidelberg: Springer, 2003
Keywords
VCr, complete-active-space self-consistent field, complete-active-space second-order perturbation theory, potential-energy curves, spectroscopic constants
Identifiers
urn:nbn:se:kau:diva-24403 (URN)
Available from: 2013-01-22 Created: 2013-01-22 Last updated: 2014-10-13
Andersson, K. (2000). Vad är det för kunskap som värderas?. Universitetsläraren, nummer 7
Open this publication in new window or tab >>Vad är det för kunskap som värderas?
2000 (Swedish)In: Universitetsläraren, nummer 7Article in journal (Other (popular science, discussion, etc.))
Identifiers
urn:nbn:se:kau:diva-25405 (URN)
Available from: 2013-01-22 Created: 2013-01-22 Last updated: 2014-10-13
Andersson, K. (1998). CASSCF second-order perturbation theory (CASPT2). In: P. von Ragué Schleyer (Ed.), Encyclopedia of Computational Chemistry: . Chichester, England: John Wiley & Sons
Open this publication in new window or tab >>CASSCF second-order perturbation theory (CASPT2)
1998 (English)In: Encyclopedia of Computational Chemistry / [ed] P. von Ragué Schleyer, Chichester, England: John Wiley & Sons , 1998Chapter in book (Refereed)
Place, publisher, year, edition, pages
Chichester, England: John Wiley & Sons, 1998
Identifiers
urn:nbn:se:kau:diva-17591 (URN)
Available from: 2013-01-21 Created: 2013-01-21 Last updated: 2014-10-13
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-6302-7006

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