Selected publications (see also Google Scholar)
Causal inference / Off-policy evaluation
N Vlassis, A Chandrashekar, FA Gil, N Kallus. Control variates for slate off-policy evaluation. NeurIPS, 2021.
N Vlassis, P Hebda, S McBride, A Noulas. On proximal causal learning with many hidden confounders. arXiv, 2020.
A Bibaut, I Malenica, N Vlassis, M Van Der Laan. More efficient off-policy evaluation through regularized targeted learning. ICML, 2019
S. Li, N. Vlassis, J. Kawale and Y. Fu. Matching via dimensionality reduction for estimation of treatment effects in digital marketing campaigns. IJCAI, 2016.
Markov decision processes / POMDPs
E. Banijamali, Y. Abbasi-Yadkori, M. Ghavamzadeh, N. Vlassis. Optimizing over a restricted policy class in MDPs. AISTATS, 2019.
F. de Nijs, G. Theocharous, N. Vlassis, M.M. de Weerdt, M.T.J. Spaan. Capacity-aware sequential recommendations. AAMAS, 2018
N. Vlassis, M.L. Littman, and D. Barber. On the computational complexity of stochastic controller optimization in POMDPs. ACM Transactions on Computation Theory 4:4, 2012.
N. Vlassis, M.L. Littman, and D. Barber. Stochastic POMDP controllers: How easy to optimize? In Proc. 10th European Workshop on Reinforcement Learning, Edinburgh, Scotland, 2012.
J.M. Porta, N. Vlassis, M.T.J. Spaan, and P. Poupart. Point-based value iteration for continuous POMDPs. Journal of Machine Learning Research, 7:2329-2367, 2006.
M.T.J. Spaan and N. Vlassis. Planning with continuous actions in partially observable environments. In Proc. IEEE Int. Conf. on Robotics and Automation, Barcelona, Spain, April 2005.
M.T.J. Spaan and N. Vlassis. Perseus: Randomized point-based value iteration for POMDPs. Journal of Artificial Intelligence Research, 24:195-220, 2005.
N. Vlassis and M.T.J. Spaan. A fast point-based algorithm for POMDPs. In Proc. Annual Machine Learning Conf. of Belgium and the Netherlands, 2004.
Reinforcement learning
G. Theocharous, Z. Wen, Y. Abbasi-Yadkori, and N. Vlassis. Scalar posterior sampling with applications. NIPS, 2018.
N. Vlassis, M. Ghavamzadeh, S. Mannor, and P. Poupart. Bayesian reinforcement learning. In Reinforcement Learning: State of the Art. M. Wiering and M. van Otterlo (eds.), Springer, 2012.
N. Vlassis and M. Toussaint. Model-free reinforcement learning as mixture learning. In Proc. Int. Conf. on Machine Learning, Montreal, Canada, 2009.
P. Poupart and N. Vlassis. Model-based Bayesian reinforcement learning in partially observable domains. In Proc. Int. Symp. on Artificial Intelligence and Mathematics, Fort Lauderdale, Florida, USA, 2008.
L. Kuyer, S. Whiteson, B. Bakker, and N. Vlassis. Multiagent reinforcement learning for urban traffic control using coordination graphs. In Proc. 19th European Conf. on Machine Learning, Antwerp, Belgium, 2008.
P. Poupart, N. Vlassis, J. Hoey, and K. Regan. An analytic solution to discrete Bayesian reinforcement learning. In Proc. Int. Conf. on Machine Learning, Pittsburgh, USA, 2006.
J.R. Kok and N. Vlassis. Collaborative multiagent reinforcement learning by payoff propagation. Journal of Machine Learning Research, 7:1789-1828, 2006.
J.R. Kok and N. Vlassis. Sparse cooperative Q-learning. In Proc. 21st Int. Conf. on Machine Learning, Banff, Canada, July 2004.
Multiagent systems / Decentralized control
F.A. Oliehoek, M.T.J. Spaan, and N. Vlassis. Optimal and approximate Q-value functions for decentralized POMDPs. Journal of Artificial Intelligence Research, 32:289-353, 2008.
M.T.J. Spaan, F.A. Oliehoek, and N. Vlassis. Multiagent planning under uncertainty with stochastic communication delays. In Proc. Int. Conf. on Automated Planning and Scheduling, Sydney, Australia, 2008.
F.A. Oliehoek, M.T.J. Spaan, S. Whiteson, and N. Vlassis. Exploiting locality of interaction in factored Dec-POMDPs. In Proc. Int. Joint Conf. on Autonomous Agents and Multi-Agent Systems, Estoril, Portugal, 2008.
N. Vlassis. A Concise Introduction to Multiagent Systems and Distributed Artificial Intelligence. Synthesis Lectures in Artificial Intelligence and Machine Learning. Morgan & Claypool Publishers, 2007.
M.T.J. Spaan, G.J. Gordon, and N. Vlassis. Decentralized planning under uncertainty for teams of communicating agents. In Proc. Int. Joint Conf. on Autonomous Agents and Multiagent Systems, Hakodate, Japan, May 2006.
J.R. Kok, P.J. 't Hoen, B. Bakker, and N. Vlassis. Utile coordination: Learning interdependencies among cooperative agents. In Proc. IEEE Symp. on Computational Intelligence and Games, Colchester, Essex, April 2005.
J.R. Kok and N. Vlassis. Using the max-plus algorithm for multiagent decision making in coordination graphs. In Proc. RoboCup Int. Symposium, Osaka, Japan, July 2005. Best paper award.
Unsupervised learning / Clustering
K. Kurihara, M. Welling, and N. Vlassis. Accelerated variational Dirichlet process mixtures. In Advances in Neural Information Processing Systems 19, 2007.
J.J. Verbeek, J.R.J. Nunnink, and N. Vlassis. Accelerated EM-based clustering of large data sets. Data Mining and Knowledge Discovery, 13(3):291-307, 2006.
J.J. Verbeek, N. Vlassis, and B. Kröse. Self-organizing mixture models. Neurocomputing, 63:99-123, 2005.
W. Kowalczyk and N. Vlassis. Newscast EM. In Advances in Neural Information Processing Systems 17, 2005.
J.J. Verbeek, S.T. Roweis, and N. Vlassis. Non-linear CCA and PCA by alignment of local models. In Advances in Neural Information Processing Systems 16, 2004.
J.J. Verbeek, N. Vlassis, and B. Kröse. Efficient greedy learning of Gaussian mixture models. Neural Computation, 15(2):469-485, 2003.
A. Likas, N. Vlassis, and J.J. Verbeek. The global k-means clustering algorithm. Pattern Recognition, 36(2):451-461, 2003.
J.J. Verbeek, N. Vlassis, and B.J.A. Kröse. A k-segments algorithm for finding principal curves. Pattern Recognition Letters, 23(8):1009-1017, 2002.
N. Vlassis, Y. Motomura, and B.J.A. Kröse. Supervised dimension reduction of intrinsically low-dimensional data. Neural Computation, 14(1):191-215, 2002.
N. Vlassis and A. Likas. A greedy EM algorithm for Gaussian mixture learning. Neural Processing Letters, 15(1):77-87, 2002.
N. Vlassis and Y. Motomura. Efficient source adaptivity in independent component analysis. IEEE Trans. Neural Networks, 12(3):559-566, 2001.
Robotics
N. Vlassis, M. Toussaint, G. Kontes, and S. Piperidis. Learning model-free robot control by a Monte Carlo EM algorithm. Autonomous Robots, 27(2):123-130, 2009.
J.M. Porta, M.T.J. Spaan, and N. Vlassis. Robot planning in partially observable continuous domains. In Proc. Robotics: Science and Systems, MIT, Cambridge, MA, June 2005.
J.R. Kok, M.T.J. Spaan, and N. Vlassis. Non-communicative multi-robot coordination in dynamic environments. Robotics and Autonomous Systems, 50(2-3):99-114, 2005.
M.T.J. Spaan and N. Vlassis. A point-based POMDP algorithm for robot planning. In Proc. IEEE Int. Conf. on Robotics and Automation, New Orleans, Louisiana, April 2004.
J.R. Kok, M.T.J. Spaan, and N. Vlassis. Multi-robot decision making using coordination graphs. In Proc. 11th Int. Conf. on Advanced Robotics, Coimbra, Portugal, June 2003.
N. Vlassis, B. Terwijn, and B.J.A. Kröse. Auxiliary particle filter robot localization from high-dimensional sensor observations. In Proc. IEEE Int. Conf. on Robotics and Automation, Washington D.C., 2002.
N. Vlassis, R. Bunschoten, and B.J.A. Kröse. Learning task-relevant features from robot data. In Proc. IEEE Int. Conf. on Robotics and Automation, pages 499-504, Seoul, Korea, May 2001.
B.J.A. Kröse, N. Vlassis, R. Bunschoten, and Y. Motomura. A probabilistic model for appearance-based robot localization. Image and Vision Computing, 19(6):381-391, 2001.
N. Vlassis, Y. Motomura, and B.J.A. Kröse. Supervised linear feature extraction for mobile robot localization. In Proc. IEEE Int. Conf. on Robotics and Automation, San Fransisco, CA, 2000.
Biology
R.M.T. Fleming, N. Vlassis, I. Thiele, and M.A. Saunders. Conditions for duality between fluxes and concentrations in biochemical networks. Journal of Theoretical Biology, 409:1-10, 2016.
N. Colombo and N. Vlassis. FastMotif: Spectral sequence motif discovery. Bioinformatics 31(16):2623-2631, 2015.
N. Vlassis and E. Glaab. GenePEN: Analysis of network activity alterations in complex diseases via the pairwise elastic net. Statistical Applications in Genetics and Molecular Biology 14(2):221-224, 2015.
C.C. Laczny, N. Pinel, N. Vlassis, and P. Wilmes. Alignment-free Visualization of Metagenomic Data by Nonlinear Dimension Reduction. Scientific Reports 4:4516, 2014.
N. Vlassis, M. Pires Pacheco, and T. Sauter. Fast reconstruction of compact context-specific metabolic network models. PLoS Computational Biology 10(1): e1003424, 2014.
Tensors
N. Colombo and N. Vlassis. A posteriori error bounds for joint matrix decomposition problems. NIPS, 2016.
N. Colombo and N. Vlassis. Tensor decomposition via joint matrix Schur decomposition. ICML, 2016.
Collaborative filtering
S. Sedhain, H. Bui, J. Kawale, N. Vlassis, B. Kveton, A. Menon, T. Bui, and S. Sanner. Practical linear models for large-scale one-class collaborative filtering. IJCAI, 2016.
Control
D. Achlioptas, F. Iliopoulos, and N. Vlassis. Stochastic control via entropy compression. ICALP, 2017.
N. Vlassis, R.M. Jungers. Polytopic uncertainty for linear systems: New and old complexity results. Systems & Control Letters 67, 9-13, 2014.
Computer vision
A. Diplaros, N. Vlassis, and T. Gevers. A spatially constrained generative model and an EM algorithm for image segmentation. IEEE Trans. Neural Networks, 18(3):798-808, 2007.