Search

Your search keyword '"Koroutchev, Kostadin"' showing total 133 results
Start Over Author "Koroutchev, Kostadin"
133 results on '"Koroutchev, Kostadin"'

1. Discovering Dataset Nature through Algorithmic Clustering based on String Compression

Author

Granados, Ana, Koroutchev, Kostadin, and Rodríguez, Francisco de Borja

Subjects
Computer Science - Information Theory
Abstract

Text datasets can be represented using models that do not preserve text structure, or using models that preserve text structure. Our hypothesis is that depending on the dataset nature, there can be advantages using a model that preserves text structure over one that does not, and viceversa. The key is to determine the best way of representing a particular dataset, based on the dataset itself. In this work, we propose to investigate this problem by combining text distortion and algorithmic clustering based on string compression. Specifically, a distortion technique previously developed by the authors is applied to destroy text structure progressively. Following this, a clustering algorithm based on string compression is used to analyze the effects of the distortion on the information contained in the texts. Several experiments are carried out on text datasets and artificially-generated datasets. The results show that in strongly structural datasets the clustering results worsen as text structure is progressively destroyed. Besides, they show that using a compressor which enables the choice of the size of the left-context symbols helps to determine the nature of the datasets. Finally, the results are contrasted with a method based on multidimensional projections and analogous conclusions are obtained.

Published
2025
Full Text
View/download PDF

2. Power Accretion in Social Systems

Author

Santalla, Silvia N., Koroutchev, Kostadin, Korutcheva, Elka, and Rodriguez-Laguna, Javier

Subjects
Physics - Physics and Society, Condensed Matter - Statistical Mechanics
Abstract

We consider a model of power distribution in a social system where a set of agents play a simple game on a graph: the probability of winning each round is proportional to the agent's current power, and the winner gets more power as a result. We show that, when the agents are distributed on simple 1D and 2D networks, inequality grows naturally up to a certain stationary value characterized by a clear division between a higher and a lower class of agents. High class agents are separated by one or several lower class agents which serve as a geometrical barrier preventing further flow of power between them. Moreover, we consider the effect of redistributive mechanisms, such as proportional (non-progressive) taxation. Sufficient taxation will induce a sharp transition towards a more equal society, and we argue that the critical taxation level is uniquely determined by the system geometry. Interestingly, we find that the roughness and Shannon entropy of the power distributions are a very useful complement to the standard measures of inequality, such as the Gini index and the Lorenz curve.

Published
2019
Full Text
View/download PDF

3. Detecting the Most Unusual Part of Two and Three-dimensional Digital Images

Author

Koroutchev, Kostadin and Korutcheva, Elka

Subjects
Physics - Data Analysis, Statistics and Probability, Computer Science - Computer Vision and Pattern Recognition, Physics - Medical Physics
Abstract

The purpose of this paper is to introduce an algorithm that can detect the most unusual part of a digital image in probabilistic setting. The most unusual part of a given shape is defined as a part of the image that has the maximal distance to all non intersecting shapes with the same form. The method is tested on two and three-dimensional images and has shown very good results without any predefined model. A version of the method independent of the contrast of the image is considered and is found to be useful for finding the most unusual part (and the most similar part) of the image conditioned on given image. The results can be used to scan large image databases, as for example medical databases., Comment: 16 pages

Published
2010

4. Thermodynamics of Information Retrieval

Author

Koroutchev, Kostadin, Shen, Jian, Koroutcheva, Elka, and Cebrian, Manuel

Subjects
Computer Science - Information Theory, Computer Science - Computation and Language, Computer Science - Social and Information Networks, E.4, G.3, H.3.3
Abstract

In this work, we suggest a parameterized statistical model (the gamma distribution) for the frequency of word occurrences in long strings of English text and use this model to build a corresponding thermodynamic picture by constructing the partition function. We then use our partition function to compute thermodynamic quantities such as the free energy and the specific heat. In this approach, the parameters of the word frequency model vary from word to word so that each word has a different corresponding thermodynamics and we suggest that differences in the specific heat reflect differences in how the words are used in language, differentiating keywords from common and function words. Finally, we apply our thermodynamic picture to the problem of retrieval of texts based on keywords and suggest some advantages over traditional information retrieval methods., Comment: 12 pages, 7 figures

Published
2009

5. Bump formation in a binary attractor neural network

Author

Koroutchev, Kostadin and Korutcheva, Elka

Subjects
Condensed Matter - Disordered Systems and Neural Networks, Condensed Matter - Soft Condensed Matter
Abstract

This paper investigates the conditions for the formation of local bumps in the activity of binary attractor neural networks with spatially dependent connectivity. We show that these formations are observed when asymmetry between the activity during the retrieval and learning is imposed. Analytical approximation for the order parameters is derived. The corresponding phase diagram shows a relatively large and stable region, where this effect is observed, although the critical storage and the information capacities drastically decrease inside that region. We demonstrate that the stability of the network, when starting from the bump formation, is larger than the stability when starting even from the whole pattern. Finally, we show a very good agreement between the analytical results and the simulations performed for different topologies of the network., Comment: about 14 pages

Published
2005
Full Text
View/download PDF

6. Structured Information in Metric Neural Networks

Author

Dominguez, David, Koroutchev, Kostadin, Serrano, Eduardo, and Rodríguez, Francisco B.

Subjects
Nonlinear Sciences - Adaptation and Self-Organizing Systems, Nonlinear Sciences - Exactly Solvable and Integrable Systems
Abstract

The retrieval abilities of spatially uniform attractor networks can be measured by the average overlap between patterns and neural states. We found that metric networks, with local connections, however, can carry information structured in blocks without any global overlap. and blocks attractors. We propose a way to measure the block information, related to the fluctuation of the overlap. The phase-diagram with the transition from local to global information, shows that the stability of blocks grows with dilution, but decreases with the storage rate and disappears for random topologies., Comment: 4 pages, 4 figures

Published
2005

7. Dynamical Neural Network: Information and Topology

Author

Dominguez, David, Koroutchev, Kostadin, Serrano, Eduardo, and Rodriguez, Francisco B.

Subjects
Computer Science - Information Retrieval, Computer Science - Neural and Evolutionary Computing
Abstract

A neural network works as an associative memory device if it has large storage capacity and the quality of the retrieval is good enough. The learning and attractor abilities of the network both can be measured by the mutual information (MI), between patterns and retrieval states. This paper deals with a search for an optimal topology, of a Hebb network, in the sense of the maximal MI. We use small-world topology. The connectivity $\gamma$ ranges from an extremely diluted to the fully connected network; the randomness $\omega$ ranges from purely local to completely random neighbors. It is found that, while stability implies an optimal $MI(\gamma,\omega)$ at $\gamma_{opt}(\omega)\to 0$, for the dynamics, the optimal topology holds at certain $\gamma_{opt}>0$ whenever $0\leq\omega<0.3$., Comment: 10pg, 5fig

Published
2005

8. Conditions for the emergence of spatial asymmetric states in attractor neural network

Author

Koroutchev, Kostadin and Korutcheva, Elka

Subjects
Condensed Matter - Statistical Mechanics, Condensed Matter - Disordered Systems and Neural Networks
Abstract

In this paper we show that during the retrieval process in a binary symmetric Hebb neural network, spatial localized states can be observed when the connectivity of the network is distance-dependent and when a constraint on the activity of the network is imposed, which forces different levels of activity in the retrieval and learning states. This asymmetry in the activity during the retrieval and learning is found to be sufficient condition in order to observe spatial localized states. The result is confirmed analytically and by simulation., Comment: 14 p

Published
2005
Full Text
View/download PDF

9. Detection of Unusual Objects and Temporal Patterns in EEG Video Recordings

Author

Koroutchev, Kostadin, Korutcheva, Elka, Kanev, Kamen, Rodríguez Albariño, Apolinar, Muñiz Gutierrez, Jose Luis, Fariñaz Balseiro, Fernando, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Bebis, George, editor, Boyle, Richard, editor, Parvin, Bahram, editor, Koracin, Darko, editor, Kuno, Yoshinori, editor, Wang, Junxian, editor, Wang, Jun-Xuan, editor, Pajarola, Renato, editor, Lindstrom, Peter, editor, Hinkenjann, André, editor, Encarnação, Miguel L., editor, Silva, Cláudio T., editor, and Coming, Daniel, editor

Published
2009
Full Text
View/download PDF

10. Written Texts as Statistical Mechanical Problem

Author

Koroutchev, Kostadin, Korutcheva, Elka, Shen, Jian, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Nierstrasz, Oscar, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Sudan, Madhu, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Vardi, Moshe Y., Series editor, Weikum, Gerhard, Series editor, Azzopardi, Leif, editor, Kazai, Gabriella, editor, Robertson, Stephen, editor, Rüger, Stefan, editor, Shokouhi, Milad, editor, Song, Dawei, editor, and Yilmaz, Emine, editor

Published
2009
Full Text
View/download PDF

11. Detecting the Most Unusual Part of a Digital Image

Author

Koroutchev, Kostadin, Korutcheva, Elka, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Brimkov, Valentin E., editor, Barneva, Reneta P., editor, and Hauptman, Herbert A., editor

Published
2008
Full Text
View/download PDF

12. Improved Storage Capacity of Hebbian Learning Attractor Neural Network with Bump Formations

Author

Koroutchev, Kostadin, Korutcheva, Elka, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Dough, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Kollias, Stefanos D., editor, Stafylopatis, Andreas, editor, Duch, Włodzisław, editor, and Oja, Erkki, editor

Published
2006
Full Text
View/download PDF

13. Factorization of Natural 4 × 4 Patch Distributions

Author

Koroutchev, Kostadin, Dorronsoro, José R., Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Nierstrasz, Oscar, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Sudan, Madhu, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Dough, Series editor, Vardi, Moshe Y., Series editor, Weikum, Gerhard, Series editor, Comaniciu, Dorin, editor, Mester, Rudolf, editor, Kanatani, Kenichi, editor, and Suter, David, editor

Published
2004
Full Text
View/download PDF

14. Mutual Information and Topology 1: Asymmetric Neural Network

Author

Dominguez, David, Koroutchev, Kostadin, Serrano, Eduardo, Rodríguez, Francisco B., Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Dough, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Yin, Fu-Liang, editor, Wang, Jun, editor, and Guo, Chengan, editor

Published
2004
Full Text
View/download PDF

15. Mutual Information and Topology 2: Symmetric Network

Author

Koroutchev, Kostadin, Serrano, David Dominguez Eduardo, Rodríguez, Francisco B., Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Dough, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Yin, Fu-Liang, editor, Wang, Jun, editor, and Guo, Chengan, editor

Published
2004
Full Text
View/download PDF

16. Statistical Structure of Natural 4 × 4 Image Patches

Author

Koroutchev, Kostadin, Dorronsoro, José R., Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Dough, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Fred, Ana, editor, Caelli, Terry M., editor, Duin, Robert P. W., editor, Campilho, Aurélio C., editor, and de Ridder, Dick, editor

Published
2004
Full Text
View/download PDF

20. INTEAMSE 2012 1st Workshop on Managing the Influence of People and Team Factors in SE

Author

Acuña Castillo, Silvia Teresita, Gómez, Marta, Koroutchev, Kostadin, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Dieste, Oscar, editor, Jedlitschka, Andreas, editor, and Juristo, Natalia, editor

Published
2012
Full Text
View/download PDF

32. Fast algorithm for detecting unusual shapes in digital images. Application to Medical Images

Author

Koroutchev, Kostadin, Korutcheva, Elka, UAM. Departamento de Ingeniería Informática, and Aprendizaje Automático (ING EPS-001)

Subjects
Informática, Image Processing, Image Statistics, Imagen Recognition
Abstract

This is an electronic version of the paper presented at the 10th WSEAS international conference on Mathematical methods, computational techniques and intelligent systems, held in Corfu Island on 2008, In this paper we introduce a fast algorithm that can detect the most unusual part of a digital image. The most unusual part of a given shape is defined as a part of the image that has the maximal distance to all non interesting shapes with the same form. The method is tested on two and three-dimensional images and have shown very good results without any predefined model. The results can be used to scan large image databases, as for example medical databases.

Published
2008

33. Hardware Independent Architecture for Autonomous Colaborative Agents

Author

González-de-Rivera, Guillermo, Ribalda Delgado, Ricardo, Koroutchev, Kostadin, Colás, José, Garrido, Javier, UAM. Departamento de Ingeniería Informática, Aprendizaje Automático (ING EPS-001), and Laboratorio de Tecnología Hombre-Computador (ING EPS-010)

Subjects
Informática, XML/RPC, Mobile robot, Wireless, WebService
Abstract

This is an electronic version of the paper presented at the 2nd International Conference on Informatics in Control, Automation and Robotics, held in Barcelona on 2005, We describe a modular mobile robot test system. This architecture allows easy inclusion of user hardware and communication modules. A client-server, XML/RPC based approach makes the system easy to program and neutral in respect to the operating system and the programming language used. The hardware modules are included using a hardware independent protocol. This feature of the system makes it very flexible and easy to use and reconfigure. The architecture by itself has support for many different communication modalities.

Published
2005

45. Improved Storage Capacity of Hebbian Learning Attractor Neural Network with Bump Formations.

Author

Kollias, Stefanos, Stafylopatis, Andreas, Duch, Włodzisław, Oja, Erkki, Koroutchev, Kostadin, and Korutcheva, Elka

Abstract

Recently, bump formations in attractor neural networks with distance dependent connectivities has become of increasing interest for investigation in the field of biological and computational neuroscience. Although the distance dependent connectivity is common in biological networks, a common fault of these network is the sharp drop of the number of patterns p that can remembered, when the activity changes from global to bump-like, than effectively makes these networks low effective. In this paper we represent a bump-based recursive network specially designed in order to increase its capacity, which is comparable with that of randomly connected sparse network. To this aim, we have tested a selection of 700 natural images on a network with N = 64K neurons with connectivity per neuron C. We have shown that the capacity of the network is of order of C, that is in accordance with the capacity of highly diluted network. Preserving the number of connections per neuron, a non-trivial behavior with the radius of the connectivity has been observed. Our results show that the decrement of the capacity of the bumpy network can be avoided. [ABSTRACT FROM AUTHOR]

Published
2006
Full Text
View/download PDF

46. Conditions for the emergence of spatially asymmetric retrieval states in an attractor neural network.

Author

Koroutchev, Kostadin and Korutcheva, Elka

Abstract

In this paper we show that during the retrieval process in a binary symmetric Hebb neural network, spatially localized states can be observed when the connectivity of the network is distance-dependent and a constraint on the activity of the network is imposed, which forces different levels of activity in the retrieval and learning states. This asymmetry in the activity during retrieval and learning is found to be a sufficient condition to observe spatially localized retrieval states. The result is confirmed analytically and by simulation. [ABSTRACT FROM AUTHOR]

Published
2005
Full Text
View/download PDF

47. Mutual information and topology 2: Symmetric network

Author

Koroutchev, Kostadin, Domínguez, David, Serrano, Eduardo, Rodríguez, Francisco de Borja, UAM. Departamento de Ingeniería Informática, and Neurocomputación Biológica (ING EPS-005)

Subjects
Discrete mathematics, Algebraic set, Informática, Phase transition, Algorithm Analysis and Problem Complexity, Small number, Discrete Mathematics in Computer Science, Topology (electrical circuits), Mutual information, Topology, Computer Communication Networks, Artificial Intelligence, Symmetric network, Word (computer architecture), Computation by Abstract Devices, Programming Techniques, Mathematics
Abstract

Proceedings of International Symposium on Neural Networks, Dalian, China, August 2004, Part I, The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-540-28647-9_4, Following Gardner, we calculate the information capacity and other phase transition related parameters for a symmetric Hebb network with small word topology in mean-field approximation. It was found that the topology dependence can be described by very small number of parameters, namely the probability of existence of loops with given length. In the case of small world topology, closed algebraic set of equations with only three parameters was found that is easily to be solved., Supported by the Spanish MCyT BFI-2003-07276 and TIC 2002-572-C02.

48. On the possibility to find coordinates by random features

Author

Asensio Pizarro, Carlos, Nedeltchev Koroutchev, Kostadin, UAM. Departamento de Ingeniería Informática, and Koroutchev, Kostadin

Subjects
Informática, Sistemas estocásticos, Variables aleatorias, ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION
Abstract

In this document we explore the possibility of using an image of the texture features on a surface for determining the absolute position of the device which extracted it, avoiding direct image comparison. As a result, we obtain a method which uses the relative positions of neighbouring features as a random code and determines the location of the device on the surface with a low probability of error and fast execution time.

Published
2014

49. Support Vector Machine Approach to Cardiac SPECT Diagnosis

Author

Ciecholewski, Marcin, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Nierstrasz, Oscar, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Sudan, Madhu, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Vardi, Moshe Y., Series editor, Weikum, Gerhard, Series editor, Aggarwal, Jake K., editor, Barneva, Reneta P., editor, Brimkov, Valentin E., editor, Koroutchev, Kostadin N., editor, and Korutcheva, Elka R., editor

Published
2011
Full Text
View/download PDF

50. Precipitates Segmentation from Scanning Electron Microscope Images through Machine Learning Techniques

Author

Papa, João P., Pereira, Clayton R., de Albuquerque, Victor H. C., Silva, Cleiton C., Falcão, Alexandre X., Tavares, João Manuel R. S., Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Nierstrasz, Oscar, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Sudan, Madhu, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Vardi, Moshe Y., Series editor, Weikum, Gerhard, Series editor, Aggarwal, Jake K., editor, Barneva, Reneta P., editor, Brimkov, Valentin E., editor, Koroutchev, Kostadin N., editor, and Korutcheva, Elka R., editor

Published
2011
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results