This document lists publications by Olli Virmajoki, including: 1) 12 refereed scientific journal articles on topics like clustering algorithms. 2) 11 articles in international scientific conferences on clustering and machine learning. 3) 4 theses including a PhD thesis on the pairwise nearest neighbor clustering method. 4) 4 technical reports from the University of Joensuu on clustering algorithms. 5) 2 other publications on virtual education and a book about pairwise nearest neighbor clustering. 6) 2 manuscripts under review on random swap clustering and legal issues during cutbacks.

1. LIST OF PUBLICATIONS
PhD Olli Virmajoki
January 13th
2015
A. Refereed Scientific Publications
Articles in Refereed International Scientific Journals
1. P. Fränti, O. Virmajoki and V. Hautamäki, "Fast agglomerative clustering using a k-nearest
neighbor graph", IEEE Trans. on Pattern Analysis and Machine Intelligence, 28 (11), 1875-
1881, November 2006.
2. P. Fränti and O. Virmajoki, "Iterative shrinking method for the clustering problems", Pattern
Recognition, 39 (5), 761-775, May 2006.
3. O. Virmajoki and P. Fränti, "Fast pairwise nearest neighbor based algorithm for multilevel
thresholding", Journal of Electronic Imaging, 12 (4), 648-659, October 2003.
4. O. Virmajoki, P. Fränti and T. Kaukoranta, "Practical methods for speeding-up the pairwise
nearest neighbor method", Optical Engineering, 40 (11), 2495-2504, November 2001.
Articles in Refereed International Scientific Conferences
1. P. Fränti and O. Virmajoki, "On the efficiency of swap-based clustering", Int. Conf. on
Adaptive and Natural Computing Algorithms (ICANNGA'09), Kuopio, Finland, 303-312, April
2009.
2. P. Fränti, O. Virmajoki and V. Hautamäki, "Probabilistic clustering by random swap
algorithm", IAPR Int. Conf. on Pattern Recognition (ICPR'08), Tampa, Florida, USA,
December 2008.
3. P. Fränti, M. Tuononen and O. Virmajoki, "Deterministic and randomized local search
algorithms for clustering", 2008 IEEE Int. Conf. on Multimedia & Expo (ICME'08), Hannover,
Germany, 837-840, June 2008.
4. O. Virmajoki and P. Fränti, "Divide-and-conquer algorithm for creating neighborhood graph for
clustering", IAPR Int. Conf. on Pattern Recognition (ICPR'04), Cambridge, United Kingdom,
vol.1, 264-267, August 2004.
5. P. Fränti and O. Virmajoki, "Genetic algorithm using iterative shrinking for solving clustering
problems", Proc. Wessex Data Mining Conf. 2003, Rio de Janeiro, Brazil, 193-204, December
2003.
6. P. Fränti, O. Virmajoki and V. Hautamäki, "Fast PNN-based clustering using k-nearest neighbor
graph", IEEE Int. Conf. on Data Mining (ICDM'03), Melbourne, Florida, USA, 525-528,
November, 2003.
7. O. Virmajoki and P. Fränti, "Multilevel thresholding by fast PNN based algorithm", SPIE Conf.
on Image Processing: Algorithms and Systems, Santa Clara, USA, SPIE Vol. 5014, 123-134,
January 2003.

2. 8. O. Virmajoki, P. Fränti and T. Kaukoranta, "Iterative shrinking method for generating
clustering", IEEE Int. Conf. on Image Processing (ICIP'02), Rochester, New York, USA, vol.
2, 685-688, September 2002.
9. P. Fränti and O. Virmajoki, "Polynomial-time clustering algorithms derived from branch-and-
bound technique", Advanced Concepts for Intelligent Vision Systems (ACIVS'2002), Ghent,
Belgium, pp. 118-123, September 2002.
10. P. Fränti, O. Virmajoki and T. Kaukoranta, "Branch-and-bound technique for solving optimal
clustering", Int. Conf. on Pattern Recognition (ICPR'02), Quebec, Canada, vol. 2, 232-235,
August 2002.
11. O. Virmajoki, P. Fränti and T. Kaukoranta, "Fast PNN using mean-distance ordered search",
Int. Conf. on Information, Communications and Signal Processing (ICICS'01), Singapore,
October 2001.
12. O. Virmajoki, P. Fränti and T. Kaukoranta, "Fast PNN using partial distortion search", Int.
Conf. on Computer Analysis of Images and Patterns (CAIP'01), Warsaw, Poland, pp. 77-84,
September 2001.
Theses
1. O. Virmajoki, “Työvoiman vähentäminen Itä-Suomen ammattikorkeakouluissa 2010 -luvun
alussa (Cutback at the Polytechnics of Eastern Finland in the Beginning of the 2010s)”, M.Sc.
(Law) Thesis (in Finnish), Law School, University of Eastern Finland, Finland, October 2013.
2. O. Virmajoki, "Pairwise Nearest Neighbor Method Revisited", Ph.D. Thesis, Department of
Computer Science, University of Joensuu, Finland, December 2004.
3. O. Virmajoki, "Konenäköosaamisen kehittäminen Kajaanin seudulle (Technology Transfer of
the Knowledge of Machine Vision for the Kajaani Region)", Ph.Lic. Thesis (in Finnish),
Department of Computer Science, University of Joensuu, Finland, February 2002.
4. O. Virmajoki, "Kuljetin- ja varastojärjestelmien simulointi suunnitteluvälineenä (Simulation
of the Transport and Warehouse Systems as a Planning Method)", M.Sc. (Tech) Thesis (in
Finnish), Department of Technical Physics, Helsinki University of Technology, Finland, May
1983.
B. Technical Reports
1. P. Fränti, O. Virmajoki and V. Hautamäki (2003): Graph-based agglomerative clustering.
University of Joensuu, Department of Computer Science, Technical Report, Series A, Report A-
2003-4.
2. P. Fränti, O. Virmajoki and T. Kaukoranta (2002): Optimal clustering by branch-and-bound
technique. University of Joensuu, Department of Computer Science, Technical Report, Series
A, Report A-2002-2.
3. O. Virmajoki, P. Fränti and T. Kaukoranta (2001): Iterative shrinking method for the clustering
problem. University of Joensuu, Department of Computer Science, Technical Report, Series A,
Report A-2001-3.
4. O. Virmajoki, P. Fränti and T. Kaukoranta (2000): Practical methods for speeding-up the PNN
method. University of Joensuu, Department of Computer Science, Technical Report, Series A,
Report A-2000-2.

3. C. Other Publications
1. O. Virmajoki, "Laadukasta opintotarjontaa Virtuaaliammattikorkeakoulun portaaliin (High
quality periods for the portal of Online University of Applied Sciences)", ISOT-seminar in
Kaukametsä, Kajaani, Finland, November 2009.
2. O. Virmajoki, "Pairwise Nearest Neighbor Clustering Method Revisited", LAP LAMBERT
Academic Publishing AG & Co. KG, Germany, April 8th
2010.
(http://www.amazon.com/Pairwise-Nearest-Neighbor-Clustering-Revisited/dp/3838339185)
D. Manuscripts in Review
1. P. Fränti, O. Virmajoki and M. Malinen, “Efficiency of Random swap clustering”, IEEE Trans.
on Knowledge and Data Engineering (submitted 13th
January 2015).
2. O. Virmajoki, “Legal protection issues at polytechnics in Finland during the cutback”,
Administrative Law Review (submitted 17th
June 2014).