Research Publications

Hans Georg Schaathun


Books

[1] Hans Georg Schaathun. Machine Learning in Image Steganalysis. John Wiley & Sons, 2012. [ bib | URL ]

Papers (peer-reviewed)

[1] Hans Georg Schaathun and Welie Annett Schaathun. Learning mathematics through classroom interaction. In SEFI MWG, 2016. To appear. [ bib | .pdf ]
[2] Welie Annett Schaathun and Hans Georg Schaathun. Mellom klassisk betinging og støttende stillas: Et utviklingspsykologisk perspektiv på ingeniørstudenters læring. In Innovasjon i velferdssamfunnet, volume 2015 of Fjordantologien, 2016. To appear. [ bib | .pdf ]
[3] A software framework for intelligent computer-automated product design. In Proceedings of the 30th European Conference on Modelling and Simulation [?]. Regensburg, Germany. [ bib ]
[4] Intelligent computer-automated crane design using an online crane prototyping tool. In Proceedings of the 30th European Conference on Modelling and Simulation [?]. Regensburg, Germany. [ bib ]
[5] Hans Georg Schaathun. Matematikk er eit pratefag og andre røynsler frå eit omvendt klasserom. Norsk Informatikkonferanse, November 2015. Presentert på Undervising og Didaktikk i IT-faga, Ålesund 23.-25, november 2015. [ bib | .pdf ]
[6] Welie Annett Schaathun and Hans Georg Schaathun. Dypevaluering av studentenes læring - Er fokusgrupper svaret? Norsk Informatikkonferanse, November 2015. Presentert på Undervising og Didaktikk i IT-faga, Ålesund 23.-25, november 2015. [ bib | .pdf ]
[7] Minoru Kuribayashi and Hans Georg Schaathun. Image fingerprinting system based on collusion secure code and watermarking method. In ICIP, Quebec, September 2015. Accepted for publication. [ bib ]
[8] Yingguang Chu, Lars Hatledal, Filippo Sanfilippo, Hans Schaathun, Vilmar Æsøy, and Houxiang Zhang. Virtual prototyping system for maritime crane design and operation based on functional mock-up interface. In OCEANS, May 2015. Genova, Italy, 18--21 May. [ bib | Preprint ]
[9] Hans Georg Schaathun. Evaluation of splittable pseudo-random generators. Journal of Functional Programming, 25, May 2015. Accepted for publication. [ bib | DOI | Preprint | URL ]
Pseudo-random number generation is a fundamental problem in computer programming. In the case of sequential processing the problem is very well researched, but parallel processing raises new problems whereof far too little is currently understood.

Splittable pseudo-random generators have been proposed to meet the challenges of parallelism. While applicable to any programming paradigm, they are designed to be particularly suitable for pure functional programming. In this paper we review and evaluate known constructions of such generators, and we identify flaws in several large classes of generators, including Lehmer trees, the implementation in Haskell's standard library, leapfrog, and subsequencing (substreaming).

Keywords: splittable pseudo-random number generators, Lehmer tree, Monte Carlo tree, parallel programming, pure functional programming, Haskell
[10] Welie Annett Schaathun, Hans Georg Schaathun, and Robin T. Bye. Aktiv læring i mikrokontrollarar. Uniped, 38(4):381--389, 2015. Special issue following MNT-konferansen, Bergen, Norway 18-19 March 2015. [ bib | .pdf ]
[11] Øivind Strand, Rigmor Einang Alnes, Hans Georg Schaathun, and Helen Berg. Drivers and barriers in public sector innovations, regional perspectives and lessons learned from the alv project. In Øivind Strand, Erik Nesset, and Harald Yndestad, editors, Fragmentering eller mobilisering? Regional Utvikling i Nordvest, volume 2014 of Fjordantologien, pages 155--174. forlag1, 2015. [ bib ]
[12] Robin T. Bye and Hans Georg Schaathun. A simulation study of evaluation heuristics for tug fleet optimisation problems. Communications in Computer and Information Science, 2015. Accepted for publication. [ bib ]
[13] Robin T. Bye and Hans Georg Schaathun. Evaluation heuristics for tug fleet optimisation algorithms: A computational simulation study of a receding horizon genetic algorithm. In Proceedings of the 4th International Conference on Operations Research and Enterprise Systems (ICORES'15), pages 270--282, 2015. [ bib | .pdf ]
[14] Hans Georg Schaathun, Sven Inge Molnes, Helen Berg, and Rigmor Einang Alnes. Electronic tracking of users with cognitive impairment (contrasting a literature review with local experience). In 2nd European Workshop on Practical Aspects of Health Informatics (PAHI 2014), volume 1251 of CEUR Workshop Proceedings, May 2014. [ bib | Open Access | .pdf ]
[15] Robin T. Bye and Hans G. Schaathun. An improved receding horizon genetic algorithm for the tug fleet optimisation problem. In Proceedings of the 28th European Conference on Modelling and Simulation, pages 682--690, May 2014. Brescia, Italy. [ bib | Preprint ]
[16] Hans Georg Schaathun. Attacks on Kuribayashi's fingerprinting scheme. Information Forensics and Security, IEEE Transactions on, 9(4):607--609, April 2014. [ bib | DOI | Preprint | Companion Source Code ]
The main threat against fingerprinting systems is collusion attacks. The attack most commonly assumed in the literature is a combination of averaging the collusion fingerprints and additive noise. In this correspondence, we demonstrate that the recently proposed fingerprinting scheme of Kuribayashi's is very vulnerable to certain nonlinear collusion attacks.

Keywords: data compression;fingerprint identification;image coding; image denoising;image watermarking; Kuribayashi fingerprinting scheme;additive noise; collusion fingerprints;fingerprinting systems; nonlinear collusion attacks;Additive noise; Detectors;Discrete cosine transforms; Educational institutions;Interference;Transform coding; Watermarking;Fingerprinting;collusion attack;watermarking
[17] Hans Georg Schaathun. Parallell slump (Om å parallellisera genetiske algoritmar i Haskell). In Norsk Informatikkonferanse, 2014. Open access at http://ojs.bibsys.no/index.php/NIK/index. ISSN 1892-0721. [ bib | .pdf ]
[18] Hans Georg Schaathun and Magne Aarset. Operational planning in state machines. Norsk informatikkonferanse (NIK), 2013. [ bib | .pdf ]
[19] Filippo Sanfilippo, Lars Ivar Hatledal, Hans Georg Schaathun, Kristin Ytterstad Pettersen, and Houxiang Zhang. A universal control architecture for maritime cranes and robots using genetic algorithms as a possible mapping approach. In Proceeding of the IEEE International Conference on Robotics and Biomimetics (ROBIO) Shenzhen, China, December 2013, pages 322--327. IEEE, 2013. [ bib | Preprint ]
[20] Hans Georg Schaathun, Magne Aarset, Runar Ostnes, and Robert Rylander. Hierarchical task analysis, situation-awareness and support software. In Webjørn Rekdalsbakken, Robin T. Bye, and Houxiang Zhang, editors, 27th European Conference on Modelling and Simulation, pages 184+. European Council for Modelling and Simulation, 2013. [ bib | .pdf ]
[21] Hans Georg Schaathun. Tekstur og dekkval i biletsteganografi. In Norsk Informatikkonferanse, Bodø, Norway, November 2012. [ bib | .pdf ]
[22] Hans Georg Schaathun. Vurdering av features for steganalyse i JPEG. In Norsk Informatikkonferanse, Tromsø, Norway, November 2011. [ bib | .pdf ]
[23] Boris Skoric, Stefan Katzenbeisser, Hans Georg Schaathun, and Mehmet Utku Celik. Tardos fingerprinting codes in the combined digit model. IEEE Transactions on Information Forensics and Security, 6(3):906--919, September 2011. [ bib | DOI ]
We formalize a new attack model for collusion secure codes, incorporating attacks on the underlying watermarking scheme as well as cut-and-paste attacks traditionally considered for collusion secure codes. We use this model to analyze the collusion resistance of two versions of the Tardos code, both for binary and nonbinary alphabets. The model allows us to consider different signal processing attacks on the content, namely the addition of noise and averaging attacks. The latter may result in content segments that have multiple watermarks embedded. We study two versions of the q-ary Tardos code in which the accusation method has been modified so as to allow for the detection of multiple symbols in the same content segment. We show that both variants yield efficient codes in the new model, parametrized for realistic attacker strengths.

Keywords: fingerprint identification;image watermarking;Tardos fingerprinting codes;accusation method;binary alphabets;collusion resistance;collusion secure codes;combined digit model;content segment;cut-and-paste attacks;nonbinary alphabets;q-ary Tardos code;signal processing attacks;watermarking scheme;Analytical models;Detectors;Mathematical model;Noise;Watermarking;Collusion attacks;fingerprinting;watermarking
[24] J.A. Briffa, H.G. Schaathun, and S. Wesemeyer. An improved decoding algorithm for the Davey-MacKay construction. In Communications (ICC), 2010 IEEE International Conference on, pages 1--5, May 2010. [ bib | DOI | Preprint ]
The Deletion-Insertion Correcting Code construction proposed by Davey and MacKay consists of an inner code that recovers synchronization and an outer code that provides substitution error protection. The inner code uses low-weight codewords which are added (modulo two) to a pilot sequence. The receiver is able to synchronise on the pilot sequence in spite of the changes introduced by the added codeword. The original bit-level formulation of the inner decoder assumes that all bits in the sparse codebook are identically and independently distributed. Not only is this assumption inaccurate, but it also prevents the use of soft a- priori input to the decoder. We propose an alternative symbol-level inner decoding algorithm that takes the actual codebook into account. Simulation results show that the proposed algorithm has an improved performance with only a small penalty in complexity, and it allows other improvements using inner codes with larger minimum distance.

Keywords: turbo codes;Davey-MacKay construction;alternative symbol-level inner decoding algorithm;deletion-insertion correcting code construction;improved decoding algorithm;inner decoder;nonbinary codes;pilot sequence;sparse codebook;substitution error protection;turbo codes;Communications Society;Decoding;Delta modulation;Demodulation;Error correction codes;Iterative algorithms;Partial transmit sequences;Peer to peer computing;Turbo codes;Watermarking
[25] B. Skoric, S. Katzenbeisser, H.G. Schaathun, and M.U. Celik. Tardos fingerprinting codes in the combined digit model. In Information Forensics and Security, 2009. WIFS 2009. First IEEE International Workshop on, pages 41--45, December 2009. [ bib | DOI ]
We introduce a new attack model for collusion-secure codes, called the combined digit model, which represents signal processing attacks against the underlying watermarking level better than existing models. In this paper, we analyze the performance of two variants of the Tardos code and show that both variants can accommodate the new model and resist collusion attacks with only a modest increase in code length as compared to the results for the commonly used restricted digit model.

Keywords: codes;watermarking;Tardos fingerprinting codes;collusion-secure codes;combined digit model;restricted digit model;signal processing;watermarking level;Codes;Data security;Fingerprint recognition;Forensics;Information security;Performance analysis;Resists;Signal processing;Signal processing algorithms;Watermarking
[26] Hans Georg Schaathun. On higher weights and code existence. In The twelfth IMA International Conference on Cryptography and Coding, Springer Lecture Notes in Computer Science, pages 56--64. Springer, December 2009. Cirencester, England. [ bib | Preprint ]
Several open questions in coding theory relate to non-existence or construction of certain optimal codes. Many previous problems of this kind have been solved by studying possible weight enumerators. A couple of authors in this decade have proposed using higher weights (generalised Hamming weights) to a similar effect. In this paper we suggest one approach based on the weight hierarchy, and it allows us to conduct an extremely rapid computer search to prove that there are exactly two inequivalent [36,8,16] codes. The technique can also be used to gain new information about the weight hierarchy of the putative [72,36,16] code, but not yet enough to say if it exists or not.

[27] Johann A. Briffa, Hans Georg Schaathun, and Ainuddin Wahid Abdul Wahab. Has F5 really been broken? In Intern. Conf. on Imaging for Crime Detection and Prevention (ICDP), December 2009. [ bib | DOI | URL ]
[28] Ainuddin Wahid Abdul Wahab, Hans Georg Schaathun, and Anthony TS Ho. Markov process based steganalysis by using second-order transition probability matrix. In 8th European Conference on Information Warfare and Security, ECIW 09, Military Academy, Lisbon and the University of Minho, Braga, Portugal, July 2009. [ bib ]
[29] Johann Briffa, Anthony TS Ho, Hans Georg Schaathun, and Ainuddin Wahid Abdul Wahab. Conditional probability based steganalysis for JPEG steganography. In International Conference on Signal Processing Systems (ICSPS 2009), May 2009. [ bib ]
[30] Ainuddin Wahid Abdul Wahab, Johann A Briffa, and Hans Georg Schaathun. On the performance of wavelet decomposition steganalysis with jsteg steganography. In Hyoung-Joong Kim, Stefan Katzenbeisser, and AnthonyT.S. Ho, editors, International Workshop on Digital Watermarking 2008, volume 5450 of Springer Lecture Notes in Computer Science, pages 342--349. Springer Berlin Heidelberg, 2009. Korea. [ bib | DOI | Preprint ]
[31] J.A. Briffa and H.G. Schaathun. Improvement of the Davey-MacKay construction. In Information Theory and Its Applications, 2008. ISITA 2008. International Symposium on, pages 1--4, December 2008. [ bib | DOI | Conference | URL ]
The Davey-MacKay construction is a deletion-insertion correcting code scheme consisting of an inner code that functions as a pilot sequence to which the receiver seeks to synchronize, and an outer code that provides error protection. We analyse the performance of the inner code in isolation, arguing that these codes provide unequal protection, and demonstrate empirically that the error rate is dependent on the date symbol values. We also propose modifications to the code construction that alleviate this asymmetry. Simulation results show that these codes have an improved performance with no penalty.

Keywords: error correction codes;Davey-MacKay construction;code construction;deletion-insertion correcting code scheme;error protection code;inner code;outer code;Decoding;Delta modulation;Error analysis;Error correction codes;Information theory;Parity check codes;Partial transmit sequences;Performance analysis;Protection;Watermarking
[32] J.A. Briffa and H.G. Schaathun. Non-binary turbo codes and applications. In Turbo Codes and Related Topics, 2008 5th International Symposium on, pages 294--298, September 2008. [ bib | DOI ]
In this paper we consider the use of q-ary turbo codes on abstract q-ary channels. Simulations show that our 16-ary codes perform well on the q-ary symmetric channel. This validates their suitability as outer codes in non-binary applications. We also compare with the performance of same codes on conventional PSK and QAM modulation, and demonstrate an application of these codes to the insertion/deletion channel.

Keywords: channel coding;phase shift keying;quadrature amplitude modulation;turbo codes;PSK modulation;QAM modulation;insertion/deletion channel;nonbinary turbo codes;q-ary channels;q-ary turbo codes;Construction industry;Decoding;Delta modulation;Error analysis;Modulation;Turbo codes;Watermarking;deletion-insertion correcting codes;non-binary codes;q-ary symmetric channel;turbo codes
[33] Hans Georg Schaathun. On the assumption of equal contributions in fingerprinting. IEEE Transaction on Information Forensics and Security, 3(3):569--572, September 2008. [ bib | DOI | Preprint ]
With a digital fingerprinting scheme, a vendor of digital copies of copyrighted material marks each individual copy with a unique fingerprint. If an illegal copy appears, it can be traced back to one or more guilty pirates due to this fingerprint. A coalition of pirates may combine their copies to produce an unauthorized copy with a false, hybrid fingerprint. It is often assumed in the literature that the members of the collusion will make equal contributions to the hybrid fingerprint, because nobody will accept an increased risk of being caught. We argue that no such assumption is valid a priori, and we show that a published solution by Sebe and Domingo-Ferrer can be broken by breaking the assumption.

Keywords: copyright;fingerprint identification;image coding;copyrighted material;digital copy protection;digital fingerprinting scheme;hybrid fingerprint;illegal copying;Collusion-attack;collusion-secure code (CSC);digital fingerprinting;scattering codes
[34] Hans Georg Schaathun. On error-correcting fingerprinting codes for use with watermarking. Multimedia Systems, 13(5--6):331--344, February 2008. [ bib | DOI | Preprint | URL ]
Digital fingerprinting has been suggested for copyright protection. Using a watermarking scheme, a fingerprint identifying the buyer is embedded in every copy sold. If an illegal copy appears, it can be traced back to the guilty user. By using collusion-secure codes, the fingerprinting system is made secure against cut-and-paste attacks. In this paper we study the interface between the collusion-secure fingerprinting codes and the underlying watermarking scheme, and we construct several codes which are both error-correcting and collusion-secure. Error-correction makes the system robust against successful attacks on the watermarking layer.

Keywords: Collusion-secure fingerprinting; Copyright protection; Error-correcting codes; Watermarking; Soft-decision decoding
[35] Hans Georg Schaathun. A key-recovery attack on authentication watermarking by Li and Yuan. In 10th ACM Workshop on Multimedia & Security, 2008. [ bib | Handouts | Slides | .pdf ]
[36] Hans Georg Schaathun. Novel attacks on spread-spectrum fingerprinting. EURASIP J. Information Security, 2008, 2008. [ bib | URL | .pdf ]
Spread-spectrum watermarking is generally considered to be robust against collusion attacks, and thereby suitable for digital fingerprinting. We have previously introduced the minority extreme attack (IWDW ’07), and showed that it is effective against orthogonal fingerprints. In this paper, we show that it is also effective against random Gaussian fingerprint. Furthermore, we develop new randomised attacks which counter the effect of the decoder preprocessing of Zhao et al.

[37] Hans Georg Schaathun. Attack analysis for He&Wu's joint watermarking/fingerprinting scheme. In The 6th International Workshop on Digital Watermarking, volume 3304 of Springer Lecture Notes in Computer Science, 2007. Canton (Guangzhou) China. [ bib | Preprint ]
[38] Hans Georg Schaathun and Marcel Fernandez-Muñoz. Soft decision decoding of Boneh-Shaw fingerprinting codes. IEICE Transactions, E89-A(10):2603--2608, October 2006. [ bib | URL | .pdf ]
[39] Hans Georg Schaathun. On watermarking/fingerprinting for copyright protection. In Innovative Computing, Information and Control, 2006. ICICIC '06. First International Conference on, volume 3, pages 50--53, Beijing, China, August 2006. [ bib | DOI | URL ]
Digital fingerprinting has been suggested for copyright protection. Using a watermarking scheme, a fingerprint identifying the buyer is embedded in every copy sold. If an illegal copy appears, it can be traced back to the guilty user. By using collusion-secure codes, the fingerprinting system is made secure against cut-and-paste attacks. In this paper we study the interface between the collusion-secure fingerprinting codes and the underlying watermarking scheme, and we construct several codes which are both error-correcting and collusion-secure. Error-correction makes the system robust against successful attacks on the watermarking layer

Keywords: error correction codes;fingerprint identification;watermarking;collusion-secure codes;copyright protection;cut-and-paste attacks;digital fingerprinting;error-correcting code;watermarking;Computer errors;Copyright protection;Decoding;Error correction codes;Fingerprint recognition;Image segmentation;Marketing and sales;Robustness;Steganography;Watermarking;collusion-secure fingerprinting;copyright protection;error-correcting codes;soft-decision decoding;watermarking
[40] Hans Georg Schaathun. The Boneh-Shaw fingerprinting scheme is better than we thought. IEEE Transaction on Information Forensics and Security, June 2006. [ bib | DOI | Preprint ]
Digital fingerprinting is a forensic method against illegal copying. The distributor marks each individual copy with a unique fingerprint. If an illegal copy appears, it can be traced back to one or more guilty pirates due to this fingerprint. To work against a coalition of several pirates, the fingerprinting scheme must be based on a collusion-secure code. This paper addresses binary collusion-secure codes in the setting of Boneh and Shaw (1995/1998). We prove that the Boneh-Shaw scheme is more efficient than originally proven, and we propose adaptations to further improve the scheme. We also point out some differences between our model and others in the literature.

Keywords: binary codes;copy protection;Boneh-Shaw fingerprinting;binary collusion-secure codes;forensic method;illegal copying;Copyright protection;Councils;Data security;Fingerprint recognition;Forensics;Law;Legal factors;Legislation;Marketing and sales;Motion pictures;Collusion-secure codes;copyright protection;digital fingerprinting (FP);traitor tracing
[41] Hans Georg Schaathun. Nested codes for constrained memory and for dirty paper. In Applied Algebra, Algebraic Algorithms and Error-Correcting Codes, Springer Lecture Notes in Computer Science. Springer-Verlag, 2006. AAECC-16, Las Vegas, USA. [ bib | Preprint ]
[42] Gérard D. Cohen and Hans Georg Schaathun. A trellis-based bound on (2, 1)-separating codes. In Cryptography and Coding, volume 3796 of Springer Lecture Notes in Computer Science. Springer-Verlag, December 2005. 10th IMA International Conference, Cirencester, England. [ bib | Preprint ]
[43] Hans Georg Schaathun. On watermarking/fingerprinting for copyright protection. In Norsk Informatikkonferanse, Bergen, Norway, November 2005. [ bib | .pdf ]
[44] Hans Georg Schaathun and Tor Helleseth. The second support weight distribution of the Kasami codes. Information Theory, IEEE Transactions on, 51(8):2892--2894, August 2005. [ bib | DOI | Preprint ]
We compute the second support weight distribution of the Kasami codes.

Keywords: Galois fields, dual codes, linear codes GF, Galois field, Kasami code, SWD, dual code, linear code, support weight distribution
[45] Hans Georg Schaathun and Marcel Fernandez-Muñoz. Boneh-Shaw fingerprinting and soft decision decoding. In Information Theory Workshop, 2005. Rotorua, NZ. [ bib | URL ]
[46] Tor Helleseth and Hans Georg Schaathun. On the (2,1)-separating weight of the Kerdock code. IEEE Trans. Inform. Theory, 50(12):3312--3315, December 2004. [ bib | DOI | Preprint ]
Separating codes find applications in many fields including automata theory and digital fingerprinting. It is known that the Kerdock code of sufficient order is (2,1)- and (2,2)-separating, but the separating weight is only known by a lower bound due to Sagalovich. In this correspondence, we prove that the lower bound on the (2,1)-separating weight is met with equality.

Keywords: automata theory;binary codes;linear codes;(2, 1)-separating weight;automata theory;binary Kerdock code;digital fingerprinting;linear codes;separating codes;Binary codes;Councils;Hamming distance;Informatics;65;Fingerprinting;Kerdock code;linear codes over;separating systems
[47] Hans Georg Schaathun. Fighting three pirates with scattering codes. In Proc. IEEE Intern. Symp. Inform. Theory, page 202, June 2004. [ bib | URL ]
[48] Hans Georg Schaathun. Duality and support weight distributions. Information Theory, IEEE Transactions on, 50(5):862--867, May 2004. [ bib | DOI | Preprint ]
We show how to compute the support weight distribution A/sub i//sup r/ for r/spl ges/k-d/sub 2//sup /spl perp//+3, where d/sub 2//sup /spl perp// is the second minimum support weight of a code, provided the weight enumerator of the dual code is known.

Keywords: dual codes dual code, support weight distribution, weight enumerator
[49] Gérard D. Cohen and Hans Georg Schaathun. Separating codes: Constructions and bounds. In LATIN 2004: Theoretical Informatics: 6th Latin American Symposium, Buenos Aires, Argentina, April 5-8, 2004. Proceedings, volume 2976, pages 322--328, April 2004. [ bib | Preprint ]
[50] Hans Georg Schaathun. On collusion-secure codes for copyright protection. In Norsk Informatikkonferanse, Stavanger, Norway, 2004. [ bib | .pdf ]
[51] Hans Georg Schaathun. A lower bound for the greedy weights of product codes. Designs, Codes, and Cryptography, 31(1):27--42, January 2004. [ bib | Preprint ]
[52] Gérard D. Cohen and Hans Georg Schaathun. Upper bounds on separating codes. IEEE Trans. Inform. Theory, 50(6):1291--1295, 2004. [ bib | DOI | Preprint ]
The combinatorial concept of separating systems has numerous applications, such as automata theory, digital fingerprinting, group testing, and hashing. In this correspondence, we derive upper bounds on the size of codes with various separating properties.

Keywords: combinatorial mathematics;error correction codes;automata theory;combinatorial concept;digital finger printing;error-correcting codes;group testing;hashing;separating codes;separating system;superimposed codes;upper bound;Cryptography;Cyclic redundancy check;Error-correcting codes;hashing;separating systems;superimposed codes
[53] Hans Georg Schaathun and Tor Helleseth. Separating and intersecting properties of BCH and Kasami codes. In Cryptography and Coding, volume 2898 of Springer Lecture Notes in Computer Science, pages 52--65. Springer-Verlag, December 2003. 9th IMA International Conference, Cirencester, England. [ bib | Preprint ]
Separating codes have recently been applied in the construction of collusion secure fingerprinting schemes. They are related to other combinatorial concepts like intersecting codes, superimposed codes, hashing families, and group testing. In this paper we study some good, binary asymptotic constructions of such codes.

Keywords: separating systems, fingerprinting, BCH codes, Kasami codes
[54] Hans Georg Schaathun. Fighting two pirates. In Applied Algebra, Algebraic Algorithms and Error-Correcting Codes, volume 2643 of Springer Lecture Notes in Computer Science, pages 71--78, May 2003. [ bib | Preprint ]
[55] Gérard D. Cohen and Hans Georg Schaathun. New upper bounds on separating codes. In 2003 International Conference on Telecommunications, February 2003. [ bib ]
[56] Hans Georg Schaathun and Wolfgang Willems. A lower bound for the weight hierarchies of product codes. Discrete Applied Mathematics, 128:251--261, 2003. Special issue for WCC 2001. [ bib | Preprint ]
[57] Gérard D. Cohen, Sylvia B. Encheva, Simon Litsyn, and Hans Georg Schaathun. Intersecting codes and separating codes. Discrete Applied Mathematics, 128(1):75--83, 2003. International Workshop on Coding and Cryptography (WCC2001). [ bib | DOI | URL | .pdf ]
Let Γ be a code of length n. Then x is called a descendant of the coalition of codewords a,b,…,e if xi∈ai,bi,…,ei for i=1,…,n. We study codes with the following property: any two non-intersecting coalitions of a limited size have no common descendant. We present constructions based on linear intersecting codes.

Keywords: Intersecting code, Separating code, Copyright protection
[58] Gérard D. Cohen, Sylvia B. Encheva, Simon Litsyn, and Hans Georg Schaathun. Erratum to: “Intersecting codes and separating codes” [Discrete Appl. Math. 128 (2003), no. 1, 75--83]. Discrete Applied Mathematics, 131(3):689--690, 2003. [ bib ]
[59] Gérard D. Cohen and Hans Georg Schaathun. New bounds on separating families. 2003. Pseudo-proceedings of the cancelled CCC'03 in Yellow Mountain, China. [ bib ]
[60] Gérard D. Cohen, Sylvia B. Encheva, and Hans Georg Schaathun. More on (2,2)-separating systems. IEEE Trans. Inform. Theory, 48(9):2606--2609, September 2002. [ bib | DOI | Preprint ]
The theory of separating systems has been applied in different areas of science and technology such as automata synthesis, technical diagnosis, and authenticating ownership claims. Constructions of (2,2)-separating systems derived from error-correcting codes are given, together with bounds on their parameters based on distance considerations.

Keywords: concatenated codes;error correction codes;linear codes;2,2-separating systems;bounds;concatenated codes;copyright protection;distance considerations;error-correcting codes;linear codes;watermarking;Linear code;Sufficient conditions;Terminology;Watermarking
[61] Hans Georg Schaathun. Duality and greedy weights for linear codes and projective multisets. In Applied Algebra, Algebraic Algorithms and Error-Correcting Codes, volume 2227 of Springer Lecture Notes in Computer Science, pages 92--101. Springer-Verlag, November 2001. AAECC-15, Melbourne, Australia. [ bib | Preprint ]
A projective multiset is a collection of projective points, which are not necessarily distinct. A linear code can be represented as a projective multiset, by taking the columns of a generator matrix as projective points. Projective multisets have proved very powerful in the study of generalised Hamming weights. In this paper we study relations between a code and its dual.

Keywords: linear codes, projective multiset, weight hierarchy, greedy weights, dual code
[62] Hans Georg Schaathun and Wolfgang Willems. A lower bound for the weight hierarchy of product codes. In Proc. IEEE Intern. Symp. Inform. Theory, page 59, June 2001. Washington DC. [ bib ]
[63] Hans Georg Schaathun. A lower bound on the greedy weights of product codes and projective multisets. In Proc. IEEE Intern. Symp. Inform. Theory, page 120, June 2001. Washington DC. [ bib | DOI ]
We present the relation between product codes and projective multisets, and give a lower bound on the greedy weights of product codes

Keywords: linear codes;set theory;greedy weights;linear codes;lower bound;product codes;projective multisets;Councils;Informatics;Linear code;Product codes;Subspace constraints;Tensile stress
[64] Hans Georg Schaathun. Upper bounds on weight hierarchies of extremal non-chain codes. Discrete Math., 241(1--3):449--469, 2001. Selected Papers in honour of Helge Tverberg. [ bib | DOI | Preprint | URL ]
The weight hierarchy of a linear [n,k;q] code C over GF(q) is the sequence (d1,d2,…,dk) where dr is the smallest support weight of an r-dimensional subcode of C. Linear codes may be classified according to a set of chain and non-chain conditions, the extreme cases being codes satisfying the chain condition (due to Wei and Yang) and extremal, non-chain codes (due to Chen and Kløve). This paper gives upper bounds on the weight hierarchies of the latter class of codes.

Keywords: Weight hierarchy, Chain condition, Linear codes, Projective multiset
[65] Conchita Martínez-Pérez, Hans Georg Schaathun, and Wolfgang Willems. On the weight hierarchies of product codes. The Wei-Yang Conjecture and more. In Daniel Augot, editor, Workshop on Coding and Cryptography, pages 373--379, January 2001. [ bib | Preprint ]
[66] Hans Georg Schaathun. The weight hierarchy of product codes. IEEE Trans. Inform. Theory, 46(7):2648--2651, November 2000. [ bib | DOI | Preprint ]
The weight of a code is the number of coordinate positions where no codeword is zero. The rth minimum weight dr is the least weight of an r-dimensional subcode. Wei and Yang (1993) gave a conjecture about the minimum weights for some product codes. In this article, we find a relation between product codes and the Segre embedding of a pair of projective systems, and we use this to prove the conjecture

Keywords: linear codes;set theory;Segre embedding;coordinate positions;linear code;minimum weight;minimum weights;product codes;projective multiset;projective systems;subcode;weight hierarchy;Informatics;Linear code;Product codes;Tensile stress;Vectors
[67] Hans Georg Schaathun. Projective systems and higher weights. In Proc. IEEE Intern. Symp. Inform. Theory, page 255, June 2000. [ bib | DOI ]
We use projective multisets (projective systems) to find upper bounds on the weight hierarchies for a special class of codes, namely the extremal non-chain codes. Several code constructions exist meeting the bounds with equality

Keywords: linear codes;code constructions;extremal nonchain codes;higher weights;linear codes;projective multisets;projective systems;upper bounds;weight hierarchies;Algebra;Binary codes;Galois fields;Hamming weight;Informatics;Upper bound

Selected technical reports and other papers

[1] Adrian Rutle and Hans Georg Schaathun. Model-driven engineering of maritime systems. In 24th Nordic Workshop on Programming Theory (NWPT), volume 403 of Tech. report, Institutt for Informatikk, Universitetet i Bergen, 2012. [ bib | .pdf ]
[2] Hans Georg Schaathun. Collusion-secure codes and digital fingerprinting. In Lian Shiguo, editor, Multimedia Communication Security: Recent Advances. Nova Science Publishers, 2009. [ bib ]
[3] Gérard D. Cohen and Hans Georg Schaathun. Asymptotic overview on separating codes. Technical Report 248, Dept. of Informatics, University of Bergen, May 2003. Available at http://www.ii.uib.no/publikasjoner/texrap/index.shtml. [ bib ]
[4] Gérard D. Cohen, Sylvia B. Encheva, and Hans Georg Schaathun. On separating codes. Technical report, Ecole Nationale Supérieure des Télécommunications, 2001. [ bib | Preprint ]

Feature articles/Opinions

  1. with Helen Berg, Brit Krøvel, Cecilie Campbell, Rigmor Einang Alnes: Internett i kommunale bustader, eit kommunalt ansvar eller ei privatsak? Sunnmørsposten 2014

Conference presentation without peer review

  1. with Welie A. Schaathun: «Mellom klassisk betinging og støttende stillas: Et utviklingspsykologisk perspektiv på ingeniørstudenters læring» Fjordkonferansen June 2015.
  2. with Yingguang Chu and Lars Ivar Hatledal and Kjetil Nordby: «Virtual Prototypes on the Web», ModProd 2015. Linkjøping, February 2015.
  3. with Adrian Rutle: «Model-Driven Engineering: Combining Structure and Behaviour of Simulation Systems», ModProd 2013. Linkjøping, February 2013.
  4. with Adrian Rutle: «Model-driven Engineering of Maritime Systems» in 24th Nordic Workshop on Programming Theory (NWPT) 2012. Tech. report no. 403, Institutt for Informatikk, Universitetet i Bergen (ISSN 0333-3590).

Invited talks

  1. «Image Forensics and Steganalysis». University of Liverpool, Department of Electronics and Electrical Engineering. 26 June 2009 (Slides and «Handouts»)
  2. «Digital Rights Management -- and other protection mechanisms for author rights» SmartHome, University of Stavanger. 26 June 2008 (Slides and «Handouts»)
  3. «Error Control Watermarking - Deletion-Insertion Correcting Codes and Robust Watermarking». University College Dublin, Department of Mathematics. 25 February 2008 (Slides and «Handouts»)

Hans Georg / georg@schaathun.net