Doctor of Philosophy, The University of Tokyo

博士(工学), 東京大学

Lempel-Ziv Code

Context Tree Weighting Method

Learning Theory

Enumerative Coding

Asymptotic Vector Quantization

Rate-Distortion Theory

Data Compression

Source Coding

Information Theory

Lempel-Ziv符号

文脈木重み付け法

学習理論

数え上げ符号

漸近的ベクトル量子化

レート歪理論

データ圧縮

情報源符号化

情報理論

Manufacturing technology (mechanical, electrical/electronic, chemical engineering), Communication and network engineering

Informatics, Information theory

Mar. 1980
The University of Tokyo, Graduate School, Division of Engineering, 計数工学専攻

Mar. 1978
The University of Tokyo, Faculty of Engineering, 計数工学科

01 Jul. 2013 - 31 Jul. 2016
委員, 国家公務員採用総合職試験（数理科学・物理・地球科学）試験専門委員会, Government

Nov. 2013 - Nov. 2015
委員長, 電子情報通信学会英文誌情報理論とその応用小特集編集委員会, Society

Nov. 2013 - Jan. 2015
委員長, 第３７回情報理論とその応用シンポジウムプログラム委員会, Society

Nov. 2013 - 2014
実行委員, 第３７回情報理論とその応用シンポジウム実行委員会, Society

May 2004 - Mar. 2012
評議員, 情報理論とその応用学会, Society

Jan. 2007 - Dec. 2008
委員, 日本学術振興会科学研究費委員会成果公開部会理工系小委員会

Sep. 2008
功績賞・業績賞委員会投票委員, 電子情報通信学会, Society

May 2001 - May 2007
情報理論研究専門委員会委員, 電子情報通信学会, Society

Apr. 2003 - Mar. 2005
東京支部評議員, 電子情報通信学会, Society

2004 - 2005
SITA奨励賞選考委員, 情報理論とその応用学会, Society

2004 - 2005
英文誌特集号編集委員, 電子情報通信学会, Society

Jan. 2002 - Dec. 2003
理事, 情報理論とその応用学会, Society

2000 - 2000
SITA奨励賞選考委員, 情報理論とその応用学会, Society

2000 - 2000
和文誌特集号編集委員, 電子情報通信学会, Society

1994 - 1995
Sacretary of Information Theory Society Tokyo Chapter, IEEE, Society

Jan. 1990 - Dec. 1993
幹事, 情報理論とその応用学会, Society

Jan. 1986 - Dec. 1987
幹事, 情報理論とその応用学会, Society

Statistical properties of double hoyt fading with applications to the performance analysis of wireless communication systems
Nazih Hajri; Neji Youssef; Tsutomu Kawabata; Matthias Pätzold; Wiem Dahech
IEEE Access, Institute of Electrical and Electronics Engineers Inc., 6, 19597-19609, 06 Apr. 2018, Peer-reviwed, In this paper, we investigate the statistical properties of double Hoyt fading channels, where the overall received signal is determined by the product of two statistically independent but not necessarily identically distributed single Hoyt processes. Finite-range integral expressions are first derived for the probability density function (PDF), cumulative distribution function (CDF), level-crossing rate (LCR), and average duration of fades of the envelope fading process. A closed-form approximate solution is also deduced for the LCR by making use of the Laplace approximation theorem. Applying the derived PDF of the double Hoyt channel, we then provide analytical expressions for the average symbol error probability of both coherent M-ary phase-shift keying and square M-ary quadrature amplitude modulation schemes. It is shown that all the obtained theoretical results include those that are already known for double Rayleigh channels as a special case. In addition, simplified expressions for the Hoyt \\times Rayleigh, Rayleigh \\times one-sided Gaussian, and double one-sided Gaussian channels are presented. Moreover, the applicableness of the proposed model to measured real-world propagation channels is examined and discussed by comparing the derived CDF and LCR with published measurement data collected in inter-vehicular propagation environments. Numerical and simulation results are also provided to confirm the validity of the derivations.
Scientific journal, English

On the Statistical Properties of Capacity Outage Intervals in OSTBC-MIMO Rayleigh Fading Channels
Rym Hicheri; Gulzaib Rafiq; Tsutomu Kawabata; Matthias Patzold; Neji Youssef
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 15, 5, 3548-3559, May 2016, Peer-reviwed, This paper deals mainly with the study of the asymptotic probability density functions (PDFs) of the outage durations of the instantaneous capacity of orthogonal space-time block code (OSTBC) multiple-input multiple-output (MIMO) systems over Rayleigh channels. Drawing upon known statistical properties for the asymptotic behavior of chi-squared processes at low levels, we provide approximate solutions for the PDF, the cumulative distribution function (CDF), and the kth-order moments of the outage intervals of the underlying capacity processes. Then, as an application of the derived PDF, the performance assessment of capacity simulators is reported. Following this, we introduce the newly defined average-to-trough capacity ratio (ATCR) metric, and investigate its PDF and CDF. The validity of the derived results is confirmed by specializing them to already known ones, although they have been obtained by using a rather different approach. The accuracy and applicability of the asymptotic analysis to practical values of capacity thresholds have been examined by means of computer simulations. The theoretical results presented contribute to the statistical characterization of outage events, the study of which has mainly been limited to the analysis of the probability, the occurrence rate, and the average duration of outages.
Scientific journal, English

Level-Crossing Rate and Average Duration of Fades in Non-Isotropic Hoyt Fading Channels with Applications to Selection Combining Diversity
Wiem Dahech; Nazih Hajri; Néji Youssef; Matthias Pätzold; Tsutomu Kawabata
Proceedings 2015 IEEE 82st Vehicular Technology Conference(VTC Fall), IEEE, 1-5, 07 Sep. 2015, Peer-reviwed
International conference proceedings, English

Statistical Analysis of the Channel Capacity Outage Intervals in Massive MIMO Systems with OSTBC over Rayleigh Fading Channels
Rym Hicheri; Nazih Hajri; N ́eji Youssef; Matthias P ̈atzold; Tsutomu Kawabata
Proceedings 2015 IEEE 81st Vehicular Technology Conference, IEEE, 1-5, 11 May 2015, Peer-reviwed
International conference proceedings, English

Performance Improvement of Iterative Multiuser Detection for Large Sparsely Spread CDMA Systems by Spatial Coupling
Keigo Takeuchi; Toshiyuki Tanaka; Tsutomu Kawabata
IEEE TRANSACTIONS ON INFORMATION THEORY, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 61, 4, 1768-1794, Apr. 2015, Peer-reviwed, Kudekar et al. proved that the belief-propagation (BP) performance for low-density parity check codes can be boosted up to the maximum a posteriori (MAP) performance by spatial coupling. In this paper, spatial coupling is applied to sparsely spread code-division multiple-access systems to improve the performance of iterative multiuser detection based on BP. Two iterative receivers based on BP are considered: 1) one receiver is based on exact BP and 2) the other on an approximate BP with Gaussian approximation. The performance of the two BP receivers is evaluated via density evolution (DE) in the dense limit after taking the large-system limit, in which the number of users and the spreading factor tend to infinity while their ratio is kept constant. The two BP receivers are shown to achieve the same performance as each other in these limits. Furthermore, taking a continuum limit for the obtained DE equations implies that the performance of the two BP receivers can be improved up to the performance achieved by the symbol-wise MAP detection, called individually optimal detection, via spatial coupling. Numerical simulations show that spatial coupling can provide a significant improvement in bit-error rate for finite-sized systems especially in the region of high system loads.
Scientific journal, English

Iterative Channel Estimation and Decoding via Spatial Coupling
Shuhei Horio; Keigo Takeuchi; Tsutomu Kawabata
IEICE Transaction on Fundamentals, Special Section on Wideband Systems, IEICE, E98-A, 2, Feb. 2015, Peer-reviwed
Scientific journal, English

A computation algorithm of the capacity of discrete memoryless channel with the input size larger than the output size
Tsutomu Kawabata; Yoshiaki Kitayama
2014 INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY AND ITS APPLICATIONS (ISITA), IEEE, 26-29, 2014, Peer-reviwed, Computation of the channel capacity for the discrete memoryless channel is considered when the input size J being larger than the output size K. In this case the Arimoto-Brahut algorithm requires considerable iterations. However, the capacity is achieved by an input distribution which is supported on the set with the size at most K. Thus we propose a new algorithm in which the original capacity computation problem is separated into the one of smaller input size and the search problem of the support set. For the former problem we can employ Nakagawa-Kanaya algorithm to avoid long iterations and for the latter we rely on the computational geometry. We implement our algorithm and compare the running time with the Arimoto-Brahut algorithm and show the effectiveness for the channel of small output size.
International conference proceedings, English

Properties of jeffreys mixture for markov sources
Jun'Ichi Takeuchi; Tsutomu Kawabata; Andrew R. Barron
IEEE Transactions on Information Theory, 59, 1, 438-457, 2013, Peer-reviwed, We discuss the properties of Jeffreys mixture for a Markov model. First, we show that a modified Jeffreys mixture asymptotically achieves the minimax coding regret for universal data compression, where we do not put any restriction on data sequences. Moreover, we give an approximation formula for the prediction probability of Jeffreys mixture for a Markov model. By this formula, it is revealed that the prediction probability by Jeffreys mixture for the Markov model with alphabet {0,1\\} is not of the form (nx\\s + α)/(ns + β), where nx\\s is the number of occurrences of the symbol x following the context s {0,1} and ns = n0\\s + n1\\s. Moreover, we propose a method to compute our minimax strategy, which is a combination of a Monte Carlo method and the approximation formula, where the former is used for earlier stages in the data, while the latter is used for later stages. © 2012 IEEE.
International conference proceedings, English

An asymptotic approximate solution to the distribution of the capacity outage intervals in OSTBC-MIMO Rayleigh fading channels
Neji Youssef; Gulzaib Rafiq; Rym Hicheri; Tsutomu Kawabata; Matthias Pätzold
IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, Fundamentals and PHY Track, 1291-1295, 2013, Peer-reviwed, This paper deals with the study of asymptotic probability density functions (PDFs) of the outage durations of the instantaneous capacity (also referred to as the mutual information) in orthogonal space-time block code (OSTBC) transceiver systems over multiple-input multiple-output (MIMO) Rayleigh fading channels. The Rayleigh fading subchannels are assumed to be frequency- nonselective and mutually uncorrelated, whereas the associated Doppler power spectral density is supposed to be symmetric about the origin. In addition, the channel state information (CSI) is considered to be available only at the receiver side. Taking these assumptions into account, and drawing upon known statistical properties for the asymptotic behavior of chi-square processes at low levels, we provide a closed-form approximate solution for the PDF of the outage intervals of the underlying capacity processes. Furthermore, an analytical expression is also provided for the kth-order moments of the outage intervals. These statistical quantities will as well be shown to be useful for studying the statistics of the capacity outage durations of single-input multiple-output (SIMO) and multiple-input single-output (MISO) systems. The validity of the obtained approximate asymptotic solutions has been confirmed by means of computer simulations. © 2013 IEEE.
International conference proceedings, English

A phenomenological study on threshold mprovement via spatial coupling
K. Takeuchi; T. Tanaka; T. Kawabata
IEICE Trans. Fundamentals, E95-A, 5, 974-977, May 2012, Peer-reviwed
Scientific journal, English

Improvement of BP-Based CDMA Multiuser Detection by Spatial Coupling
K. Takeuchi; T. Tanaka; T. Kawabata
Proc. 2011 IEEE International Symposium on Information Theory, 1629-1633, Aug. 2011, Peer-reviwed
International conference proceedings, English

A Revisit to The Muroga Method of Computing Channel Capacity
Tsutomu Kawabata
Proceedings of 2010 International Symposium on Information Theory and its Applications, 801‐806, Oct. 2010, Peer-reviwed
International conference proceedings, English

Closest Point Algorithms with $l_{p}$ Norm for Root Lattices
K. Takizawa; H. Yagi; T. Kawabata
The IEICE Transactions on Fundamentals (Japanese Edition), Vol.J93-A, No.4, pp.289-299, Apr. 2010, Peer-reviwed
Scientific journal, Japanese

Closest Point Algorithms with l(p) Norm for Root Lattices
Kenichirou Takizawa; Hideki Yagi; Tsutomu Kawabata
2010 IEEE INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY, IEEE, 1042-1046, 2010, Peer-reviwed, We study quantizers with l(p) norm, with p >= 1, for the root lattices. Our algorithms extend the ones proposed by Conway and Sloane [1] with l(2) norm. They proposed an interesting algorithm for A(n) lattice, but without proof of the optimality. We give the proof of the optimality with our extended case of l(p) norm. We also give an algorithm for E(6) and its dual, which are not described in [1].
International conference proceedings, English

BEP Performance of M2M Communications over Frequency Flat Double Hoyt Fading Channels
Nazih Hajri; Neji Youssef; Fethi Choubani; Tsutomu Kawabata
2010 IEEE 21ST INTERNATIONAL SYMPOSIUM ON PERSONAL INDOOR AND MOBILE RADIO COMMUNICATIONS (PIMRC), IEEE, 1962-1966, 2010, Peer-reviwed, The performance analysis of mobile-to-mobile (M2M) radio communications over double Hoyt fading channels perturbed by additive white Gaussian noise (AWGN) is considered. First, the probability density function (PDF) of the instantaneous signal-to-noise ratio (SNR) per bit is derived under the assumption that the fading channel is a concatenation (product) of two independent but not necessarily identically distributed Hoyt processes. Then, an expression for the bit error probability (BEP) is investigated for several modulation schemes commonly used in wireless communication systems. In the derivation, the underlying propagation channel is assumed to be slowly varying and having the frequency-flat fading characteristics. Numerical results, considering the impact of the fading severity on the BEP, are presented. Furthermore, the validity of the theoretical results is checked by means of computer simulations for some of the modulation schemes used in the analysis. The obtained BEP expression is general and includes, as special cases, results corresponding to the channel combinations given by RayleighxHoyt, Rayleighxone-sided Gaussian, Hoytxone-sided Gaussian, double one-sided Gaussian, and double Rayleigh fading channels.
International conference proceedings, English

On the Probability Density Functions of Outage and Inter-Outage Durations of the Capacity of Rayleigh Fading Channels
Neji Youssef; Tsutomu Kawabata
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 8, 2, 529-534, Feb. 2009, Peer-reviwed, Approximations for the probability density functions (PDFs) of the capacity outage and inter-outage durations over Rayleigh fading channels are studied. Exact closed form expressions for the Rice probability functions of the level-crossing intervals of the capacity process are derived, assuming a symmetrical Doppler power spectral density (PSD). These probability functions, which are obtained by applying the classical level-crossing theory, are known to describe the PDFs of outage and inter-outage durations only over their initial behavior. Additionally, the derived quantities are used to calculate approximate solutions for the considered PDFs based on the assumption of statistical independence between the level-crossing intervals. Numerical examples, considering Rayleigh mobile-to-mobile fading channels, are presented together with simulation results to illustrate the analysis and examine the validity of the derived expressions. Particularly, it is shown that the theoretical results obtained provide accurate approximations for the PDFs of outage and inter-outage durations at low and high outage levels, respectively.
Scientific journal, English

Enumerative Implementation of Lempel-Ziv 77 Algorithm
Tsutomu Kawabata
2008 IEEE INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY PROCEEDINGS, VOLS 1-6, IEEE, 990-994, 2008, Peer-reviwed, For each 1 = 1, 2, 3,... recursively, we define w(l) to be the unique prefix of x(l)(infinity), which is in the external leaf set of the trie {lambda, w(1),w(2),..., w(l-1)}, for a given data x(1)(infinity). This definition gives the Lempel-Ziv 77 parsing and associated data compression algorithm. We give a simple implementation which utilizes an enumerative code. Furthermore, we introduce and apply a simple post-processing mechanism which matches to this code.
International conference proceedings, English

On the redundancy of modified Lempel-Ziv parsing algorithm for Markovian source
Katsuya Kobayashi; Bing Chang Koh; Tsutomu Kawabata
2008 INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY AND ITS APPLICATIONS, VOLS 1-3, IEEE, 1117-1121, 2008, Peer-reviwed, Plotnik, Weinberger and Ziv's state dependent version of Lempel-Ziv Incremental Parsing Algorithm is analyzed for Markovian source and in particular the first order expected redundancy is obtained. The. result is compared with an experiment.
International conference proceedings, English

A Post-Processing for the Enumerative Code Implementation of Ziv-Lempel Incremental Parsing
Tsutomu Kawabata
IEICE Transactions on Communications, E90-B, 11, 3263-3235, Nov. 2007, Peer-reviwed
Scientific journal, English

A Capacity Formula for Multi-Input Erasure Channel
Tsutomu Kawabata
IEICE Transactions on Fundamentals, E90-A, 9, 1881-1884, Sep. 2007, Peer-reviwed
Scientific journal, English

Exponential Curvature of Markov Models
Jun'ichi Takeuchi; Tsutomu Kawabata
Proceedings 2007 IEEE International Symposium on Information Theory, 2891-2895, Jun. 2007, Peer-reviwed
International conference proceedings, English

Broadcasting for Dirty Printers
Kamal Elkhaili; Tsutomu Kawabata
Proceedings of 2006 IEEE International Symposium on Information Theory, 759-762, Jul. 2006, Peer-reviwed
International conference proceedings, English

Statistical Curvature and Stochastic Complexity
J.-I. Takeuchi; A. Barron; T. Kawabata
Proceedings of the 2nd International Symposium on Information Geometry and its Applications, 29-36, Dec. 2005, Peer-reviwed
International conference proceedings, English

Theoretical analysis of a zero-redundancy estimator with a finite window for memoryless source
MM Rashid; T Kawabata
PROCEEDINGS OF THE IEEE ITSOC INFORMATION THEORY WORKSHOP 2005 ON CODING AND COMPLEXITY, IEEE, 171-175, 2005, Peer-reviwed, A zero-redundancy estimator is defined by a weighted sum of Krichevsky-Trofimov (KT) sequential probability estimators i.e., the minimax bayes; of the memoryless process, over all possible alphabets. This estimator is effective for non-binary sources whose alphabet is embedded in a larger alphabet. We propose a new weighting recursive computation. Next we use the estimator to construct a finite window predictor for lossless data compressor, and we show that its average redundancy for memoryless source has optimal 1st order asymptotics.
International conference proceedings, English

Redundancy of symbol decomposition algorithms for memoryless source
T Kawabata; Y Yanagisawa
2005 IEEE International Symposium on Information Theory (ISIT), Vols 1 and 2, IEEE, 500-504, 2005, Peer-reviwed, The symbol decomposition algorithm is proposed by Willems et.al. as an efficient and practical symbol predictor applicable for compressing multi-alphabet data. However, no theoretical analysis of the algorithm has been presented. In this paper, we first elucidate a natural parameterization that the algorithm assumes and derive a prior distribution on which the algorithm is based. Based on this framework, we first analyze the redundancy of the algorithm for memoryless source with a structured alphabet. Then we interpret the algorithm compared with the Krichevsky-Trofimov estimator for multi-alphabet, through the prior distribution over our parameterization. We will here demonstrate an effectiveness of the algorithm through a computer simulation of the redundancy, and also reveal a non-optimal character. Finally, we propose a practical modification of the symbol decomposition algorithm, and show that the it achieves the asymptotic optimal redundancy.
International conference proceedings, English

Analysis of zero-redundancy estimator with a finite window for Markovian source
Mohammad M. Rashid; Tsutomu Kawabata
IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, Institute of Electronics, Information and Communication, Engineers, IEICE, E88-A, 10, 2819-2825, 2005, Peer-reviwed, Prediction of actual symbol probability is crucial for statistical data compression that uses arithmetic coder. Krichevsky-Trofimov (KT) estimator has been a standard predictor and applied in CTW or FWCTW methods. However, KT-estimator performs poorly when non occurring symbols appear. To rectify this we proposed a zero-redundancy estimator, especially with a finite window(Rashid and Kawabata, ISIT2003) for non stationary source. In this paper, we analyze the zero-redundancy estimators in the case of Markovian source and give an asymptotic evaluation of the redundancy. We show that one of the estimators has the per symbol redundancy given by one half of the dimension of positive parameters divided by the window size when the window size is large. Copyright © 2005 The Institute of Electronics, Information and Communication Engineers.
International conference proceedings, English

A Zero-Redundancy Estimator for the Context Tree Weighting Method with a Finite Window
Mohammad M. Rashid; Tsutomu Kawabata
Proceedings 2003 IEEE International Symposium on Information Theory, 114, Jun. 2003, Peer-reviwed
International conference proceedings, English

Asymptotic Two-Stage Multi-Dimensional Quantizer
Tsutomu Kawabata
Proceedings 2003 IEEE International Symposium on Information Theory, 484, Jun. 2003, Peer-reviwed
International conference proceedings, English

A new approach in the asymptotic two-stage multi-dimensional quantizer
Tsutomu Kawabata
Proceedings Workshop on Concepts in Information Theory, A. J. Han Vink Ed., Breisach, 48-49, Jun. 2002
International conference proceedings, English

The redundancy of Laplace estimator based on finite window for a Markovian source
T. Kawabata; T. Watanabe; Z. B. Rasin
IEICE Transactions on Fundamentals (Japanese Edition) -Special Section on Universal Coding and Data Compression, J84-A, 5, 705-713, Jun. 2001, Peer-reviwed
Scientific journal, Japanese

Enumerative Aspects and Asymptotics of Some Uniform Nonlinear Binary Array
T. Kawabata
Proceedings 2001 IEEE International Symposium on Information Theory, 63, Jun. 2001, Peer-reviwed
International conference proceedings, English

Enumerating the Uniform Switching System by K-sets
T. Kawabata
IEICE Transactions on Fundamentals, E84-A, 5, 1256-1260, May 2001, Peer-reviwed
Scientific journal, English

A context tree weighting algorithm with an incremental context set
T. Kawabata; F.M.J.Willems
IEICE Transactions on Fundamentals, E83-A, 10, 1898-1903, Oct. 2000, Peer-reviwed
Scientific journal, English

A note on a sequence related to the Lempel-Ziv parsing
T. Kawabata
IEICE Transactions on Fundamentals, E83-A, 10, 1979-1982, Oct. 2000, Peer-reviwed
Scientific journal, English

Noiseless Source Coding Theorems with Stationary and Mixing Cost Functions
T. Kawabata
Proceedings 2000 Cornell Summer Workshop on Information Theory, 15-16, Aug. 2000
International conference proceedings, English

Visalization of Berry spin-redirection phase in polarization interferometer with geometric shear
A.V. Tavrov; Y. Miyamoto; T. Kawabata; M. Takeda; V.V. Andreev
Proceedings of SPIE, 12-20, Jul. 2000, Peer-reviwed
International conference proceedings, English

Asymptotic Two-Stage Two-Dimensional Quantizer
T. Kawabata
Proceedings 2000 IEEE International Symposium on Information Theory, 152, Jun. 2000, Peer-reviwed
International conference proceedings, English

Imaging with Berry phase in polarization interferometer with geometric shear
A. V. Tavrov; Y. Miyamoto; T. Kawabata; M. Takeda; V. A. Andreev
FOM 2000, International Workshop on Focus on Microscopy（Shirahama, Japan）, 44, Apr. 2000, Peer-reviwed
International conference proceedings, English

Interferometric microimaging based on geometrical spin-redirection phase
Alexander V. Tavrov; Yoko Miyamoto; Tsutomu Kawabata; Mitsuo Takeda; Vladimir A. Andreev
Optics Letters, Optical Society of America (OSA), 25, 7, 460-462, 01 Apr. 2000, Peer-reviwed, A novel scheme for an interferometric microscope with which to visualize a geometrical spin-redirection phase image that represents the local inclination of microsurface structures of an object is proposed. The observed phase depends on the state of polarization and the optical constants of the object material, which enable one to distinguish the spin-redirection phase from the conventional dynamical-phase. A preliminary experiment was performed, and the phase images obtained were found to be consistent with those predicted by computer simulation based on a theoretical model. © 2000 Optical Society of America.
Scientific journal, English

Generalized algorithm for the unified analysis and simultaneous evaluation of geometrical spin-redirection phase and Pancharatnam phase in a complex interferometric system
AV Tavrov; Y Miyamoto; T Kawabata; M Takeda; VA Andreev
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION, OPTICAL SOC AMER, 17, 1, 154-161, Jan. 2000, Peer-reviwed, To permit unified analysis and simultaneous evaluation of geometrical spin-redirection phase and Pancharatnam phase, the conventional 2 x 2 Jones matrix calculation is generalized and a new scheme of 3 x 3 matrix calculation is proposed. With the proposed algorithm one can trace the polarization state changes and the geometric phase shifts caused by beam propagation along an arbitrary optical path that involves both reflection and refraction at surfaces with Fresnel shift and birefringence. (C) 2000 Optical Society of America [S0740-3232(00)01801-9].
Scientific journal, English

Improvement of upper bound to the optimal average cost of the variable length binary code
Tsutomu Kawabata
IEICE Transactions on Fundamentals, E82-A, 10, 2208-2209, Oct. 1999, Peer-reviwed
Scientific journal, English

On complexity of computing the permanent of a rectangular matrix
Tsutomu Kawabata; Jun Tarui
IEICE Transactions on Fundamentals, E82-A, 5, 741-744, May 1999, Peer-reviwed
Scientific journal, English

A method to evaluate the geometrical spin-redirection phase for a non-planar ray
Alexander V. Tavrov; Tsutomu Kawabata; Mitsuo Takeda; Yoko Miyamoto; Vladimir V. Andreev
Journal of the Optical Society of America, A, 16, 4, 919-921, Apr. 1999, Peer-reviwed
Scientific journal, English

Redundancy of the Krichevsky-Trofimov-Estimator with a Finite Window for a Markovian Source
T. Kawabata; N. Tasaki
IEICE Transactions on Fundamentals (Japanese Edition), The Institute of Electronics, Information and Communication Engineers, J82-A, 1, 112-118, Jan. 1999, Peer-reviwed, KrichevskyとTrofimovにより提案された予測確率推定量は, 有限長の窓に基づいた推定量に修正することができ, これを用いて非定常な情報源にも適したデータ圧縮アルゴリズムを実現できることが知られている. 本論文では, 次数がdの有限アルファベット定常マルコフ情報源にこの推定量を適用した場合の1シンボル当りの冗長度を解析する. 結果は, 窓の長さBを大きくしたとき, 漸近的に(有効状態数)×(アルファベットサイズ-1)/2B(nats)で与えられる. この解析には更新過程を応用する.
Scientific journal, Japanese

Efficient algorithm for the evaluation of geometric shift of polarization in interferometric and polarimetric systems
AV Tavrov; Y Miyamoto; T Kawabata; M Takeda; VV Andreev
INTERFEROMETRY '99: TECHNIQUES AND TECHNOLOGIES, SPIE-INT SOC OPTICAL ENGINEERING, 3744, 347-357, 1999, Peer-reviwed, To enable unified analysis and simultaneous evaluation of geometrical spin-redirection phase and Pancharatnam phase, conventional 2 x 2 Jones matrix calculation is generalized and a new scheme of 3 x 3 matrix calculation is proposed. By the proposed algorithm one can trace the polarization state changes and the geometric phase shifts caused by the beam propagation along an arbitrary optical path that involves both reflection and refraction at surfaces with Fresnel shift and birefringence.
International conference proceedings, English

Implementation of geometrical spin-redirection phase in interferometric measuremnts
Alexander V. Tavrov; Mituso Takeda; Yoko Miyamoto; Tsutomu Kawabata; Vlafimir V. Andreev
Conf. Laser Optics 98, St. Petersburg, Russia, 22-26, Jun. 1998, Peer-reviwed
International conference proceedings, English

A Context Tree Weighting Algorithm with a Finite Window
H. Sakaguchi; T. Kawabata
IEICE Transactions on Fundamentals (Japanese Edition), J80-A, 12, 2155-2163, 1997, Peer-reviwed
Scientific journal, Japanese

A Note on Lempel-Ziv-Yokoo Algorithm
J.Kiyohara; T. Kawabata
IEICE Transactions on Fundamentals, E79-A, 9, 1460-1463, 1996, Peer-reviwed
Scientific journal, English

Approximation of Bayes code for Markov Sources
J.-I. Takeuchi; T. Kawabata
Proceedings 1995 IEEE International Symposium on Information Theory, 391, 1995, Peer-reviwed
International conference proceedings, English

Exact analysis of the Lempel-Ziv algorithm for Unifilar Markov Source
T. Kawabata
Proceedings IEEE International Symposium on InformationTheory, 13, 1994, Peer-reviwed
International conference proceedings, English

Improvement of upper bound to the optimal average cost of the variable length code
T. Kawabata; K. Kobayashi
Proceedings IEEE International Symposium on Information Theory, 188, 1994, Peer-reviwed
International conference proceedings, English

The Rate-Distortion Dimension of Sets and Measures
Tsutomu Kawabata; Amir Dembo
IEEE Transactions on Information Theory, 40, 5, 1564-1572, 1994, Peer-reviwed, Data compression of independent samples drawn from a fractal set is considered. The asymptotic ratio of rate to magnitude log distortion characterizes the effective dimension occupied by the underlying distribution. This quantity is shown to be identical to Renyi's information dimension. For self-similar fractal sets this dimension is distribution dependent—in sharp contrast with the behavior of absolutely continuous measures. The rate-distortion dimension of a set is defined as the maximal rate-distortion dimension for distributions supported on this set. Kolmogorov's metric dimension is an upper bound on the rate-distortion dimension, while the Hausdorff dimension is a lower bound. Examples of sets for which the rate-distortion dimension differs from these bounds are provided. © 1994 IEEE
Scientific journal, English

Exact analysis of the Lempel-Ziv algorithm for I.I.D. source
T. Kawabata
Proceedings IEEE International Symposium on InformationTheory, 112, Jan. 1993, Peer-reviwed
International conference proceedings, English

Exact Analysis of the Lempel—Ziv Algorithm for I.I.D. Sources
Tsutomu Kawabata
IEEE Transactions on Information Theory, 39, 2, 698-702, 1993, Peer-reviwed, A new analysis shows that, when we apply the Lempel—Ziv ncremental parsing algorithm to an i.i.d., source with probabilities Pi, i = 1,…, m, the expected length E|Wt| of the tth parsed segment Wt isgiven by [formula omitted], with the null productbeing 1. It is also shown that [formula omitted] for thesame source with the entropy H(X). This gives a variable-to-fixed length(VF) scheme version of the Ziv—Lempel universal coding theorem. © 1993 IEEE.
Scientific journal, English

Uniform Switching System by Families of Switching Sets
Tsutomu Kawabata
IEEE Transactions on Information Theory, 39, 2, 479-490, 1993, Peer-reviwed, The signal set for the uniform switching system by a family S of switching sets is defined as S (=def{ (S1. • • •Sm) : S1E S for all t Ñ”M, and {t Ñ” M : S1Ñ” i} | = even for all i EN, where N = {1. • •. n} and M = { 1., m1}. Their exact cardinalities for important families S C 2Nare formulated and their asymptotics are determined. A computationally efficient index system is given in the case S = (NK). The error correctability for this system is also studied particularly when the errors are concentrated on an unknown epoch to E M or on an unknown wire i0 Ñ” N. Deterministic and random error-correction probabilities are calculated by the use of a combinatorial lemma. Some asymptotics are discussed. © 1993 IEEE.
Scientific journal, English

SEPARABILITY OF INTERNAL REPRESENTATIONS IN MULTILAYER PERCEPTRONS WITH APPLICATION TO LEARNING
H TAKAHASHI; E TOMITA; T KAWABATA
NEURAL NETWORKS, PERGAMON-ELSEVIER SCIENCE LTD, 6, 5, 689-703, 1993, Peer-reviwed, It is mathematically investigated as to what kind of internal representations are separable by single output units of three-layer perceptrons. A topological description is given for the necessary and sufficient condition that hidden layer representations of input patterns are separable by the output unit. An efficient algorithm is proposed for checking whether or not a hidden layer representation is linearly separable and, if not, for specifying inseparable portions in the partition. Application of the algorithm to learning of three-layer perceptrons is presented in which redundant units are utilized to reduce inseparable partition into separable one. Polynomial learnability from examples and queries is shown for the proposed learning algorithm.
Scientific journal, English

A GLOBAL MESSAGE NETWORK EMPLOYING LOW EARTH-ORBITING SATELLITES
J KANIYIL; J TAKEI; S SHIMAMOTO; Y ONOZATO; T USUI; OKA, I; T KAWABATA
IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 10, 2, 418-427, Feb. 1992, Peer-reviwed, A global message communication network for low density traffic, employing satellites at low altitudes, is the subject of this paper. This network affords round the clock service to any part of the globe, including the polar regions. Such a network can accommodate static and mobile user terminals simultaneously. The oblate globe is modeled as a regular polyhedron with 12 facets for setting up the orbits. Satellites are positioned uniformly in low-altitude symmetrical orbits. The symmetrical orbits are those whose axes are symmetrical in the three-dimensional space. We study the coverage aspects of the 6-orbit scheme and the 10-orbit scheme, each with satellites deployed at an altitude of 5000 km. At this altitude, the terrestrial user terminals can access satellites at a grazing angle of 45-degrees. The method of access over the cross-links is considered to be the slotted ALOHA scheme. For low density traffic, the down-link and up-link throughput rates are estimated. Simulation results agree with these analytical estimates for low values of network offered load.
Scientific journal, English

The Structure of the I-Measure of a Markov Chain
Tsutomu Kawabata
IEEE Transactions on Information Theory, 38, 3, 1146-1149, 1992, Peer-reviwed, The underlying mathematical structure of Shannon’s information measures was studied in a recent paper by Yeung, and the I-Measure μf, which is a signed measure defined on a proper σ-field. 9-, was introduced. The I-Measure is a natural extension of Shannon’s information measures and is uniquely defined by them. They also introduced as a consequence the I-Diagram as a geometric tool to visualize the relationship among the information measures. In general, an I-Diagram for n random variables must be constructed in n-1 dimensions. It is shown that for any finite collection of random variables forming a Markov chain, μ f assumes a very simple structure which can be illustrated by an I-Diagram in two dimensions, and μ* is a nonnegative measure. © 1992 IEEE
Scientific journal, English

Satellite Constellations for a Multiple LEQ Satellites Network(jointly anthored)
臼井 智徳; 川端 勉; 岡 育夫; 小野里 好邦
The Transactions of The IEICE, 電子情報通信学会基礎・境界ソサイエティ, J75-A, 8, 1370-1378, 1992, Peer-reviwed
Scientific journal, Japanese

Preliminary aspects of a global message network employing low earth-orbiting satellites
J. Kaniyil; J. Takei; S. Shimamoto; Y. Onozato; T. Usui; I. Oka; T. Kawabata
AIAA, 112, 1992, Peer-reviwed
International conference proceedings, English

A New Implementation of the Ziv-Lempel Incremental Parsing Algorithm
T. Kawabata; H. Yamamoto
IEEE Transactions on Information Theory., 37, 5, 1439-1440, Sep. 1991, Peer-reviwed
Scientific journal, English

A new implementation of the Ziv-Lempel incremental parsing algorithm
T. Kawabata
Proceedings IEEE Workshop on Communications, 11, Jun. 1991, Peer-reviwed
International conference proceedings, English

Statistical Composition of High-Scoring Segments from Molecular Sequences
S. Karlin; A. Dembo; T. Kawabata
Annals of Statistics, 12, 2, 571-581, Jun. 1990, Peer-reviwed
Scientific journal, English

Information rates for Poisson processes
H. Sato; T. Kawabata
Proceedings IEEE International Symposium on InformationTheory, 114-115, 1988, Peer-reviwed
International conference proceedings, English

Differential geometrical theory of asymptotically optimal Voronoi structure and its experimental verifications
T. Kawabata
Proceedings IEEE International Symposium on InformationTheory, 226, 1988, Peer-reviwed
International conference proceedings, English

First Passage Time Intervals of Gaussian Process
H. Perez; T. Kawabata; T. Mimaki
Japanese Journal of Applied Physics, 26, 8, 1378-1383, Aug. 1987, Peer-reviwed
Scientific journal, English

Information Rates for Poisson Processes
H. Sato; T. Kawabata
The Transaction of the IEICE, E70, 9, 1987, Peer-reviwed
Scientific journal, English

Level-crossing Problem of a Gaussian Process Having Gaussian Power Spectrum Density
T. Mimaki; H. Myoken; T. Kawabata
Japanese Journal of Applied Physics, 24, 4, L278-L280, Apr. 1985, Peer-reviwed
Scientific journal, English

Some experimental results on first passage time problems for Gaussian processes
H. Perez; T. Kawabata; T. Mimaki
Noise in Physical Systems and 1/f Noise, !, 1985, Peer-reviwed
International conference proceedings, English

A Post-Processing Mechanism for Sequential Use of Static and Dynamic Enumerative Code
Tsutomu Kawabata
A bijection between a complete set of source words and a complete set of codewords defines a variable-to-variable length (VV) source code. Such code is used to parse sequentially a source sequence into codewords. In a naive parsing of a finite source sequence, the last incomplete source word requires a separate post-processing. However, if the sizes of the source and the code alphabet are the same and an end-offile is available, we show that there is an abstract and compact method for the post-processing. Furthermore, when a VV code is a concatenation of VF (variable-to-fixed length) source code and a complete FV (fixed-to-variable length) integer code, we propose a simple enumerative code implementation, which can be used for processing the last word before the end-of-file. This reduces the programming complexities compared with a naive post-processing. Furthermore, we apply the implementation to a dictionary trie based method for lossless data compressions, in particular, to the Ziv-Lempel incremental parsing algorithm. Finally, we extend the description in the binary alphabet to the one in a non-binary alphabet., 電気通信大学, Dec. 2007, Bulletin of the University of Electro-Communications, 20, 36, 23-30, English, Peer-reviwed, Introduction other, 0915-0935, 120006315656, AN10016842

文脈木重み付け法とその周辺
Tsutomu Kawabata
情報理論とその応用学会, Feb. 2003, 情報理論とその応用学会ニューズレター, 47, Japanese, Invited, Lecture materials

Multimedia- A Multidisciplinary Approach to Complex Issues (I. Karydis, Eds)
Hideki Yagi; Tsutomu Kawabata
English, Joint work, Polynomial-time codes against averaging attack for multimedia fingerprinting, InTech, Jan. 2012

プログラミングによる計算可能性理論
甘利俊一; 金谷健一; 川端 勉 共訳
Japanese, Joint translation, 第４，５，６章, サイエンス社, 1987

有限窓重み付け記号分解法とその冗長度解析
橋元 雄祐; 川端 勉
Oral presentation, Japanese, 第４２回情報理論とその応用シンポジウム（SITA2019)予稿集, 電子情報通信学会情報理論とその応用サブソサイエティ, 鹿児島県霧島市, Domestic conference
27 Nov. 2019

Information and Dimension in Source Coding
Tsutomu Kawabata
Oral presentation, Japanese, IEICE Technical Report,Vol.119,No.149,p.55, Invited, Information Theory Society, Tokyo, 情報理論的結果の中には様々な形で次元が現れる．例えば，連続分布のレート歪関数は高解像度において
（分布の台の次元） log(1=歪) のように振る舞う，またパラメトリックな情報源に対するユニバーサル符号の冗長度
は（パラメータ空間の次元=2） log データ長のように振る舞う，等である．本講演ではこうした関係に魅せられた著者が，如何にこれらの関係を一般化したか，その実際における意味はなにか，等について述べたいと思う．, Domestic conference
26 Jul. 2019

マルコフ情報源に対する有限窓zero冗長度推定量の性能解析 ～ アルファベットが状態毎に未知である場合 ～
橋元雄祐; 川端 勉
Oral presentation, Japanese, 電子情報通信学会技術研究報告, 電子情報通信学会, 東京都調布市, Domestic conference
07 Mar. 2019

Asymptotic Tightness of the Shannon Lower Bound for the Rate-distortion Function of Self-similar Measures
Shingo Taguchi; Tsutomu Kawabata
Oral presentation, Japanese, Proceedings 2018 Symposium on Information Theory and Its Applications, IEICE, Iwaki, Fukushima, Domestic conference
18 Dec. 2018

Universal Source Coding with Estimated Prior 〜Algorithm and Redundancy Analysis for Singular Prior〜
Ryosuke Ikarashi; Tsutomu Kawabata
Oral presentation, Japanese, Proceedings 2018 Symposium on Information Theory and Its Applications, IEICE, Iwaki, Fukushima, Domestic conference
18 Dec. 2018

事前分布の推定に基づく無歪情報源符号の冗長度解析--エルゴート性に関する仮定の緩和--
五十嵐椋介; 川端勉
Oral presentation, Japanese, 電子情報通信学会情報理論研究会, 電子情報通信学会, 東京理科大, Domestic conference
08 Mar. 2018

Introduction to the lossless source coding and the context tree weighting method
Tsutomu Kawabata
Keynote oral presentation, English, 2017 International Symposium for Advanced Computing and Information Technology (ISACIT 2017), Invited, Asia Pacific Society for Computing and Information Technology, Sun Moon Lake, Taiwan, In this talk, we introduce fundamental ideas of lossless source coding with particular emphasis on the context tree weighting (CTW) method.
After an introduction, we give a brief overview of important compression methods, like LZ algorithms, Burrows-Wheeler Transform, Grammar based algorithms, and the CSE algorithm. Then we focus on and introduce the probabilistic or Bayesian coding methods, where the compression algorithm was organized so as to be based on probabilistic modeling and arithmetic coding. The Bayesian coding method enables us to construct a coding probability from a probabilistic model. In 1995, Willems, Shtarkov, and Tijalkens, discovered a recursive Bayesian mixing method (CTW method) for the probabilistic model called tree source, which had then been regarded as a promising Markovian source. We then introduce their idea concisely and show its redundancy as a theoretical performance. Finally, we talk about extensions of CTW methods, as many as time permits; to the unbounded context tree, the non-stationary source, and the multiple size alphabet., International conference
18 Aug. 2017

レート歪関数のシャノン下界の漸近的最適性 ～ 自己相似分布に対する別証明 ～
田口慎吾; 川端勉
Oral presentation, Japanese, 電子情報通信学会情報理論研究会, 電子情報通信学会情報理論研究会, 千葉大学（西千葉キャンパス）, Domestic conference
13 Jul. 2017

Lempel-Ziv-Yokoo データ圧縮法の簡素な実現と冗長度の実験的解析
黎 漢; 川端 勉
Oral presentation, Japanese, 東京支部学生会研究発表会（第22回）, 電子情報通信学会東京支部学生会, 東海大学 高輪キャンパス, Domestic conference
04 Mar. 2017

Redundancy Analysis of Universal Noiseless Source Coding via Estimation of Prior
Naoya Matsukami; Tsutomu Kawabata
Oral presentation, Japanese, Proceedings the 39th Symposium on Information Theory and its Applications, IEICE情報理論とその応用サブソサイエティ, Takayama, Gifu, Bayesian mixture is a standard method in realizing a universal noiseless source code for parametric source. For memoryless source, a mixture with non-discrete prior has an asymptotic redundancy proportional to the half of log data length, with the Renyi information dimension of the prior as a proportional coefficient.
In this paper, we do not assume the knowledge of a prior, but assume that some unknown non-linear discrete time dynamical system with an attractor with a known Renyi information dimension outputs the parameter. For encoding new data, we use the knowledge of a past series of data sequences, each of which is generated by the probability with the parameter output by the system. For this scheme, we ropose a novel prior and show a useful redundancy result for the associated new code., Domestic conference
13 Dec. 2016

A Method to Compress Text with Known Context Free Grammars
Ryoma Konishi; Tsutomu Kawabata
Oral presentation, Japanese, Proceedings of the 2016 IEICE General Conference, IEICE, Kyushu Univ., Domestic conference
18 Mar. 2016

Redundancy of Bayesian Code with Markov Fractal Prior Distributions
Naoya Matsukami; Tsutomu Kawabata
Oral presentation, Japanese, IEICE Technical Report, IEICE, Tokyo, Domestic conference
Mar. 2016

Improving Compression via Substring Enumeration for Degenerated Markov Sources
Takaichi Akiyama; Tsutomu Kawabata
Oral presentation, Japanese, The 37th Symposium on Information Theory and its Applications, IEICE Information Thoery Sub-Society, Unazuki, Toyama, Domestic conference
09 Dec. 2014

On the Redundancy of CSE Lossless Compression Algorithm for Degenetated Markov Sources
T. Akiyama; T. Kawabata
Public symposium, Japanese, 第３６回情報理論とその応用シンポジウム, IEICE, Ito
Nov. 2013

On Computing the Capacity of Discrete Memoryless Channel with Larger Input Alphabet Size
Y.Kitayama; T.Kawabata
Public symposium, Japanese, 第３６回情報理論とその応用シンポジウム, IEICE, Ito
Nov. 2013

Iterative Channel Estimation and Decoding via Spacial Coupling
S. Horio; K. Takeuchi; T. Kawabata
Public symposium, Japanese, 第３６回情報理論とその応用シンポジウム, IEICE, Ito
Nov. 2013

Bilipschitz Coding
Zhao Qi Li; Tsutomu Kawabata
Public symposium, Japanese, 第３６回情報理論とその応用シンポジウム, IEICE, Ito
Nov. 2013

Interpolation of Reconstruction Condition for Compressed Sensing--Extended Implications of Restricted Isometry Property--
中嶋伸輔; 川端勉
Oral presentation, Japanese, IEICE
Jul. 2013

記号分解法の改良と言語アルファベット情報源圧縮への適用
忠木勇太; 川端勉
Oral presentation, Japanese, 電子情報通信学会技術研究報告,信学技報
Jan. 2013

情報理論のひろがり ～ スタンフォード滞在で得たこと ～
川端 勉
Invited oral presentation, Japanese, 電子情報通信学会情報理論研究会「若手研究者のための講演会」, 電子情報通信学会
Dec. 2012

Large-System Analysis of Data-Dependent User Selection with General Modulation for MIMO Broadcast Channels
K.Takeuchi; R. Mueller; T. Kawabata
Public symposium, English, Proceedings of the 35th Symposium on Information Theory and Its Applications, IEICE Subsociety of Information Theory and Its Applications, Beppu
Dec. 2012

Analysis on the Fingerprinting Capacity for the Memoryless and Fair Collusion Attacks
T.Narita; H.Yagi; T. Kawabata
Public symposium, Japanese, 第３５回情報理論とその応用シンポジウム, IEICE, Beppu
Dec. 2012

自己相似な事前分布による無歪情報源符号の漸近的冗長性
久富彰人; 竹内啓悟; 川端勉
Public symposium, Japanese, 第34回情報理論とその応用シンポジウム予稿集, IEICE情報理論とその応用サブソサイエティ, 岩手
Nov. 2011

The asymptotic redundancy of lossless source coding with the self-similar prior distribution
Akihito Hisatomi; Tsutomu Kawabata
Public symposium, English, Workshop on Ergodic Theory, Information Theory, and Computer Science, Invited, 統計数理研究所, 東京, Domestic conference
Mar. 2011

ベクトルブロードキャスト通信路に対するデータ依存型ユーザ選択法
Keigo Takeuchi; Tsutomu Kawabata
Public symposium, Japanese, 第３３回情報理論とその応用シンポジウム予稿集, 情報理論とその応用学会, 松代
Dec. 2010

Redundancy analysis of the universal source code with a singular prior
Tatsuya Hashimoto; Tsutomu Kawabata
Oral presentation, Japanese, IEICE Technical Report
Mar. 2010

A Revisit to Muroga Method of Computing Channel Capacity
Tsutomu Kawabata
Public symposium, English, Proceedings of the 32nd Symposium on Information Theory and Its Applications, Society of Information Theory and Its Applications, Yuda-Onsen, Yamaguchi
Dec. 2009

Closest Point Algorithms for Root Lattice $E_{6}$ and the Dual Lattice
K. Takizawa; H. Yagi; T. Kawabata
Public symposium, Japanese, Proceedings of the 32nd Symposium on Information Theory and Its Applications, Society of Information Theory and Its Applications, Yuda0Onsen, Yamaguchi
Dec. 2009

Closest Point Algorithms with lp Norm for Root Lattices
Kenichirou TAKIZAWA; Hideki YAGI; Tsutomu KAWABATA
Public symposium, Japanese, 第３１回情報理論とその応用シンポジウム, Society of Information Theory and Its Applications, 鬼怒川
Oct. 2008

Ryoma FUJITA, Tsutomu KAWABATA
Weighted Symbol Decomposition Method; its Redundancy
Public symposium, Japanese, 第３１回情報理論とその応用シンポジウム, Society of Information Theory and Its Applications, 鬼怒川
Oct. 2008

Exponential Bounds on Decoding Performance with Weight Spectrum for Correlated Parallel Channels
Hideki Yagi; Manabu Kobayashi; Tsutomu Kawabata
Public symposium, English, The 31th Symposium on Information Theory and Its Applications, Society of Information Theory and Its Applications, Kinugawa
Oct. 2008

Fast quantization with lp norm to the An lattice
Kenichiro Takizawa; Hideki Yagi; Tutomu Kawabata
Oral presentation, Japanese, IEICE Technical Report
May 2008

The Rate-Distortion Dimension of ’Markovian’ Fractal Measures
Yasuyuki CHINEN; Tsutomu KAWABATA
Public symposium, Japanese, The 30th Symposium on Information Theory and its Applications, The Society of Information Theory and Its Applications, Kashikojima
Nov. 2007

Fast An lattice quantization and discrete convex analysis
Tsutomu KAWABATA; Ken-iiro Takizawa; Shun Endo
Public symposium, Japanese, The 30th Symposium on Information Theory and its Applications, The Society of Information Theory and Its Applications, Kashikojima
Nov. 2007

A Universal Portfolio Based on Context Tree Weighting Method
Ryoma Fujita; Tsutomu Kawabata
Oral presentation, Japanese, IEICE Technical Report
May 2007

離散定常情報源の確率構造について
川端 勉; 竹内 純一
Public symposium, Japanese, 第２９回情報理論とその応用シンポジウム予稿集, 情報理論とその応用学会, 函館
Nov. 2006

二次元ガウス密度に対する二段階一様格子量子化器の設計
小野 博督; 川端 勉
Public symposium, Japanese, 第２９回情報理論とその応用シンポジウム予稿集, 情報理論とその応用学会, 函館
Nov. 2006

マルコフ情報源に対する文脈依存増分分解法の性能評価について
小林 且弥; 川端 勉
Public symposium, Japanese, 第２９回情報理論とその応用シンポジウム予稿集, 情報理論とその応用学会, 函館
Nov. 2006

On the distribution densities of capacity fade and inter-fade time intervals over SISO Rayleigh mobile fading channels
Neji Youssef; Tsutomu Kawabata
Oral presentation, English, IEICE Technical Report
Oct. 2006

Tree Source and Stochastic Complexity
Jun'ichi Takeuchi; Tsutomu Kawabata
Public symposium, Japanese, 第４回シャノン理論ワークショップ, 情報理論とその応用学会, 城崎
Sep. 2006

無歪みデータ圧縮入門--算術符号とＣＴＷ法を中心として
川端 勉
Invited oral presentation, Japanese, 情報とダイナミックス研究集会, 九州大学
Aug. 2006

Text Compression Algorithms --An Approach from Probabilistic Modelling--
Tsutomu Kawabata
Invited oral presentation, English, Tutorial workshop on game-theoretic probability and related topics, Superrobust Computation Project, Tokyo, Japan, International conference
Mar. 2006

Volume and Surface Area of n-Sphere -- An Elementary Proof and Implications in Communications
Tsutomu Kawabata
Public symposium, Japanese, 第２８回情報理論とその応用シンポジウム, Society of Information Theory and Its Applications, 沖縄県恩納村
Nov. 2005

Broadcasting for Dirty Printers
Kamal Elkhaili; Tsutomu Kawabata
Public symposium, English, Proceedings of the 28th Symposium on Information Theory and Its Applications, Society of Information Theory and Its Applications, Onna, Okinawa
Nov. 2005

Redundancy of Symbol Decomposition Algorithms for Memoryless Source
Tsutomu Kawabata
Others, English, Superrobust Computation Project, Invited, Univ.of Tokyo, Domestic conference
Aug. 2005

On Muroga's Method for Channel Capacity
Tsutomu Kawabata
Public symposium, English, Proceedings of the 27th Symposium on Information Theory and Its Applications, Proceedings of the 27th Symposium on Information Theory and Its Applications
Dec. 2004

記号分解法を用いた無歪みデータ圧縮器の冗長度について
柳澤 陽; 川端 勉
Public symposium, Japanese, 第27回情報理論とその応用シンポジウム予稿集, 情報理論とその応用学会, 下呂
Dec. 2004

Theoretical Analysis of Zero-redundancy Estimator with a Finite Window for a Memoryless Source
Mohammad M. Rashid; Tsutomu Kawabata
Public symposium, English, Proceedings of the 17th Symposium on Information Theory and Its Applications, Society of Information Theory and Its Applications, Gero
Dec. 2004

An Analysis of Two-Stage Multi-Dimensional Quantizer with Geodesic Compander
Tsutomu Kawabata
Public symposium, English, Proceedings of the 26th Symposium on Information Theory and Its Applications, Proceedings of the 26th Symposium on Information Theory and Its Applications
Dec. 2003

二次元ガウス密度に対する漸近的二段階量子化器の性能評価
竹下智彦; 川端勉
Public symposium, Japanese, 第２６回情報理論とその応用シンポジウム予稿集, SITA
Dec. 2003

文脈木重み付け法とその周辺
川端 勉
Invited oral presentation, Japanese, SITA News Letter, Invited, SITA, Domestic conference
Feb. 2003

A new approach in the asymptotic two-stage multi-dimensional quantizer
Tsutomu Kawabata
Oral presentation, English, 2002 IEEE International Symposium on Information Theory, http://isit02.epfl.ch :Recent_Results/online
Jul. 2002

Asymptotic Two-Stage Multi-Dimensional Quantizer
Tsutomu Kawabata
Oral presentation, English, IEICE Technical Report
May 2002

Asymptotic quantization with non-difference distortion measure and its geometry
川端 勉
Public symposium, Japanese, RIKEN BSI FORUM, 情報幾何ワークショップ, 理化学研究所 BSI FORUM
Feb. 2002

A zero-redundancy estimator for the context tree weighting method with a finite window
Mohammad M. Rashid; Tsutomu Kawabata
Oral presentation, English, IEICE Technical Report
Jan. 2002

一般ひずみ測度にもとづく漸近的二段階量子化
赤松良昭; 青木良賢; 川端 勉
Public symposium, Japanese, 第２４回情報理論とその応用シンポシウム予稿集, SITA
Dec. 2001

An Image Compression Based on Quadtree and Variable Block Truncation Code
A. Khawne; T. Kawabata; S. Noppanakeepong
Oral presentation, English, 電子情報通信学会,信学技報,IT2001-39
Sep. 2001

Property of Jeffreys Mixture for Markov Sources
J-I Takeuchi; T. Kawabata; A. Barron
Public symposium, English, Proc. of 2001 Workshop on Infomation-Based Induction Science
Jul. 2001

``Property of Jeffreys Mixture for Markov Sources''
J-I Takeuchi; T. Kawabata; A. Barron
Public symposium, English, ２００１年情報論的学習理論ワークショップ
Jul. 2001

Enumerative aspects and asymptotics of nonlinear binary arrays
T. Kawabata
Public symposium, English, Proc. The 23th Symposium on Information Theory and Its Applications, SITA
Oct. 2000

二次元二段階量子化器と調和クラスタ分割について
青木良賢; 赤松良昭; 川端 勉
Public symposium, Japanese, 第23回情報理論とその応用シンポシウム予稿集, SITA
Oct. 2000

Geometrical spin redirection phase: ray tracing and imaging
A. Tavrov; Y. Miyamto; T. Kawabata; M. Takeda
Oral presentation, English, Extended Abstract, Optics Japan 2000
Oct. 2000

Noiseless Source Coding Theorems with Stationary and Mixing Cost Functions
T. Kawabata
Public symposium, English, Proceedings 2000 Cornell Summer Workshop on Information Theory, Cornell Univ., International conference
Aug. 2000

漸近的最適ベクトル量子化における現象と幾何
川端 勉
Oral presentation, Japanese, 第3回情報幾何ワークショップ, 大阪大学, Domestic conference
Dec. 1999

漸近的最適ベクトル量子化における現象と幾何
川端 勉
Invited oral presentation, Japanese, 第3回情報幾何ワークショップ,大阪大学, Invited, 大阪大学, Domestic conference
Dec. 1999

Noiseless source coding theorems with stationary and mixing cost functions
T. Kawataba
Public symposium, English, Proc. The 22th Symposium on Information Theory and Its Applications, 第22回情報理論とその応用シンポシウム予稿集
Nov. 1999

二次元漸近的量子化器の最適化に関する実験的検討
小林 宰; 川端 勉
Public symposium, Japanese, 第22回情報理論とそのその応用シンポシウム予稿集, SITA
Nov. 1999

情報測度の同定問題-四確率変数の場合-
会沢伸也; 川端 勉
Public symposium, Japanese, 第22回情報理論とその応用シンポシウム予稿集, SITA
Nov. 1999

Variable length code with generalized cost functions
T. Kawataba
Public symposium, English, Proc. 1999 Workshop on Information-Based Induction Science, 1999年情報論的学習理論ワークショップ
Aug. 1999

Asymptotic Two-Stage Quantizer
T. Kawabata
Invited oral presentation, English, Proceedings of Memorial Workshop for the 50th Anniversary of the Shannon Theory, Invited, SITA, Domestic conference
Jan. 1999

漸近的二段階量子化への新しいアプローチ
川端 勉
Invited oral presentation, Japanese, 1998年エルゴート理論・情報理論とその周辺ワークショップ, Invited, 1998年エルゴート理論・情報理論とその周辺ワークショップ, Domestic conference
Dec. 1998

Interferometric microimaging based on geometrical spin-redirection phase
Alexander V. Tavrov; Mitsuo Takeda; Yoko Miyamoto; Tsutomu Kawabata; Vladimir Andreev
Oral presentation, English, Optics Japan 99, Extended Abstracts
Nov. 1998

Asymptotic Two-Stage Quzntizer
T. Kawabata
Public symposium, English, 1998年情報論的学習理論ワークショップ, Society of Information Theory and Its Applications, 修善寺
Jul. 1998

A method to evaluate the geometrical spin-redirection phase for a non-planar ray. (jointly anthored)
Alexander V. Tavrov; Yoko Miyamoto; Tsutomu Kawabata; Mitsuo Takeda; Vlafimir V. Andreev
Oral presentation, English, Optics Japan
Jun. 1998

Conditional Version of Kac's Lemma
T. Kawabata
Public symposium, English, Proc. The 20th Symposium on Information Theory and Its Applications, 第20回情報理論とその応用シンポジウム予稿集
1997

A context tree weighting algorithm with an incremental context set(jointly anthored)
T. Kawabata; F.M.J. Willems
Public symposium, English, Proc. The 18th Symposium on Information Theory and Its Applications, 第18回情報理論とその応用シンポジウム予稿集
1995

"ベイズ符号と文脈木重みづけ法"
川端 勉
Oral presentation, Japanese, 電子情報通信学会研究技術報告, 電子情報通信学会
1994

多値情報源に対するCTW法の実現
横尾 直弘; 川端 勉
Oral presentation, Japanese, 電子情報通信学会秋季大会講演論文集
1994

"ベイズ符号によるマルコフ情報源のデータ圧縮アルゴリズムについて"
竹内 純一; 川端 勉
Public symposium, Japanese, 第17回情報理論とその応用シンポシウム予稿集, SITA
1994

"情報源符号化の二つの基本アルゴリズム"
川端 勉
Invited oral presentation, Japanese, 電子情報通信学会秋季大会講演論文集, Invited, 電子情報通信学会, Domestic conference
1994

文脈木重みづけ法の簡素な実現ならびにその正当性の証明
横尾 直弘; 川端 勉
Oral presentation, Japanese, 電子情報通信学会技術研究報告,情報理論研究会(IT)
1994

"VFユニバーサル情報源符号化-確率解析の新しい応用分野として-"
川端 勉
Oral presentation, Japanese, 電子情報通信学会研究技術報告, 電子情報通信学会, Domestic conference
1993

"A note on a sequence related to the Lempel-Ziv parsing"
T. Kawabata
Oral presentation, English, 電子情報通信学会研究技術報告, 電子情報通信学会, Domestic conference
1992

"語頭条件を満たすOn-to型VF符号化方式の提案"
高橋 大志; 川端 勉
Public symposium, Japanese, 第13回情報理論とその応用シンポシウム予稿集, SITA
Jan. 1991

"複数の低軌道衛星通信ネットワークにおける軌道決定と衛星配置[II]"
川端 勉; 臼井 智徳; 岡 育夫; 小野里 好邦; 馬場 博幸; 木村 博茂
Oral presentation, Japanese, 電子情報通信学会春季全国大会講演論文集, 電子情報通信学会, Domestic conference
1991

予測型ユニバーサルデータ圧縮器に関する一考察-2進有限次数マルコフモデルの次数推定における局所トラップの問題
石丸 勝洋; 川端 勉
Oral presentation, Japanese, 第14回情報理論とその応用シンポシウム予稿集, 情報理論とその応用学会, 指宿、鹿児島, Domestic conference
1991

Rate Distorsion Functions for Self-Similar Sets(long paper)
T. Kawabata; A. Dembo
Invited oral presentation, English, Proceedings IEEE International Symposium on Information Theory, Invited, IEEE, International conference
1991

"語頭条件を満たさないOn-to型VF符号化方式の提案"
高橋 大志; 川端 勉
Oral presentation, Japanese, 電子情報通信学会技術研究報告, 電子情報通信学会, Domestic conference
1990

線形時間でハフマン符号を構成できる分布のクラスについて-1-優幾何分布-
川端 勉; 雨宮 孝
Public symposium, Japanese, 第12回情報理論とその応用シンポジウム予稿集, SITA
1989

Explicit limit distribution of the maximal merit of word in the independent random sequence with negative expectation
T. Kawabata; S. Karlin
Public symposium, English, Proc. The 12th Symposium on Information Theory and Its Applications, SITA
1989

"線形時間でハフマン符号を構成できる分布のクラスについて-1-優幾何分布-"
川端 勉; 雨宮 孝
Public symposium, Japanese, 第12回情報理論とその応用シンポジウム予稿集
1989

"Explicit limit distribution of the maximal merit of word in the independent random sequence with negative expectation"
T. Kawabata; S. Karlin
Public symposium, English, 第12回情報理論とその応用シンポジウム予稿集
1989

二次元非一様最適ボロノイ構造に関する微分幾何学的理論とその実験的検証
川端 勉; 内山 健一
Oral presentation, Japanese, 形の科学会シンポジウム予稿集, 形の科学会, Domestic conference
1987

マルコフ情報源に関するVF算術符号の情報圧縮率
川端 勉
Public symposium, Japanese, 第9回情報理論とその応用シンポジウム予稿集, SITA
1986

"マルコフ情報源に関するVF算術符号の情報圧縮率"
川端 勉
Public symposium, Japanese, 第9回情報理論とその応用シンポジウム予稿集
1986

"正六角形定理の一般化"
川端 勉
Oral presentation, Japanese, 情報理論とその応用研究会・第8回シンポジウム資料, 情報理論とその応用研究会, Domestic conference
1985

"パラメータ分散推定量を利用したユニバーサルデータ圧縮"
伊藤 秀一; 川端 勉
Oral presentation, Japanese, 情報理論とその応用研究会・第8回シンポジウム資料, 情報理論とその応用研究会, Domestic conference
1985

漸近的最良ベクトル量子化器に固有な転位密度
川端 勉; 佐藤 洋
Public symposium, Japanese, 情報理論とその応用研究会・第7回シンポジウム資料, SITA, Domestic conference
1984

"漸近的最良ベクトル量子化器に固有な転位密度"
川端 勉; 佐藤 洋
Public symposium, Japanese, 情報理論とその応用研究会・第7回シンポジウム資料
1984

産業連関表の部門分析に関する実証的研究
川端 勉
Others, Japanese, 機械工業における製品別生産技術の動向分析のための調査研究報告書(鳥居泰彦委員長）,全国統計協会連合会
Mar. 1982

データ圧縮基礎（夜間主）
The University of Electro-Communications

情報通信と符号化
The University of Electro-Communications

データ圧縮基礎（夜間主）
The University of Electro-Communications

データ圧縮基礎（夜間主）
電気通信大学

情報通信と符号化
The University of Electro-Communications

データ圧縮基礎
The University of Electro-Communications

情報理論
The University of Electro-Communications

大学院技術英語（I専攻 情報通信システムコース）
The University of Electro-Communications

確率統計
The University of Electro-Communications

Information Theory
The University of Electro-Communications

大学院技術英語（I専攻 情報通信システムコース）
The University of Electro-Communications

大学院技術英語（I専攻 情報通信システムコース）
電気通信大学

Ｉｎｔｒｏｄｕｃｔｉｏｎ ｔｏ Ｉｎｆｏｒｍａｔｉｏｎ Ｔｈｅｏｒｙ ａｎｄ Ｃｏｄｉｎｇ
The University of Electro-Communications

情報通信と符号化
電気通信大学

確率統計
The University of Electro-Communications

確率統計
電気通信大学

データ圧縮基礎
The University of Electro-Communications

データ圧縮基礎
電気通信大学

情報理論
The University of Electro-Communications

情報理論
電気通信大学

日本応用数理学会

IEEE

電子情報通信学会

情報理論とその応用学会