Hiroshi Sakai

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34ranked-venue papers
13as first author
1since 2021 · last 2026
—ORCID · conflict

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Artificial intelligence and machine learning · 22 · 8 first-authorDatabases, data management, data science and information retrieval · 10 · 3 first-authorTheory of computation · 6 · 4 first-author · 1 since 2021Systems, architecture and hardware · 3Graphics, computer vision, multimedia, augmented reality and games · 2 · 1 first-authorApplied, interdisciplinary, general and emerging computing · 2Software engineering, systems software and programming languages · 1
YearPublicationVenuePosition
2026 Separating Subversion forcing Axioms
abstract
Abstract We study a family of variants of Jensen’s subcomplete forcing axiom , upper S upper C upper F upper A comma $\mathsf {SCFA,}$ S C F A , and subproper forcing axiom , upper S u b upper P upper F upper A $\mathsf {SubPFA}$ S u b P F A . Using these, we develop a general technique for proving nonimplications of upper S upper C upper F upper A $\mathsf {SCFA}$ S C F A , upper S u b upper P upper F upper A $\mathsf {SubPFA}$ S u b P F A and their relatives and give several applications. For instance, we show that upper S upper C upper F upper A $\mathsf {SCFA}$ S C F A does not imply upper M upper A Superscript plus Baseline left parenthesis sigma $\mathsf {MA}^+(\sigma $ M A + ( σ -closed) and upper S u b upper P upper F upper A $\mathsf {SubPFA}$
Corey Bacal Switzer, Hiroshi Sakai
J. Symb. Log.2
2020 NIS-Apriori-based rule generation with three-way decisions and its application system in SQL
Hiroshi Sakai, Michinori Nakata, Junzo Watada
Inf. Sci.1
2019 An Apriori-based Data Analysis on Suspicious Network Event Recognition
abstract
Apriori-based rule generators, which are powered by the DIS-Apriori algorithm and the NIS-Apriori algorithm, are applied to analyze the data sets available in the IEEE BigData 2019 Cup: Suspicious Network Event Recognition. Then, each missing value in the test data set is decided by using the obtained rules. The advantage of our rule-based model is that the obtained rules are very easy to understand in comparison with other ”black-box” machine learning models. Furthermore, two algorithms preserve the logical property ”completeness,” so they generate rules without excess and deficiency. In evaluation, the AUC measure seems unfavorable to our model, so we employed 3-fold cross-validation for the training data set, and we obtained a 94% mean score. This result ensures the validity of our model. We report several meaningful results in this experiment, as well as the estimation of missing values.
Zhiwen Jian, Hiroshi Sakai, Junzo Watada, Arunava Roy, M. Hilmi B. Hassan
IEEE BigData2
2019 On the existence of skinny stationary subsets
Yo Matsubara, Hiroshi Sakai, Toshimichi Usuba
Ann. Pure Appl. Log.2
2018 Rules Induced from Rough Sets in Information Tables with Continuous Values
Michinori Nakata, Hiroshi Sakai, Keitarou Hara
IPMU (2)2
2016 A proposal of a privacy-preserving questionnaire by non-deterministic information and its analysis
abstract
We focus on a questionnaire consisting of three-choice question or multiple-choice question, and propose a privacy-preserving questionnaire by non-deterministic information. Each respondent usually answers one choice from the multiple choices, and each choice is stored as a tuple in a table data. The organizer of this questionnaire analyzes the table data set, and obtains rules and the tendency. If this table data set contains personal information, the organizer needs to employ the analytical procedures with the privacy-preserving functionality. In this paper, we propose a new framework that each respondent intentionally answers non-deterministic information instead of deterministic information. For example, he answers `either A, B, or C' instead of the actual choice A, and he intentionally dilutes his choice. This may be the similar concept on the k-anonymity. Non-deterministic information will be desirable for preserving each respondent's information. We follow the framework of Rough Non-deterministic Information Analysis (RNIA), and apply RNIA to the privacy-preserving questionnaire by non-deterministic information. In the current data mining algorithms, the tuples with non-deterministic information may be removed based on the data cleaning process. However, RNIA can handle such tuples as well as the tuples with deterministic information. By using RNIA, we can consider new types of privacy-preserving questionnaire.
Shusaku Tsumoto, Michinori Nakata, Hiroshi Sakai
IEEE BigData3
2016 Describing Rough Approximations by Indiscernibility Relations in Information Tables with Incomplete Information
Michinori Nakata, Hiroshi Sakai
IPMU (2)2
2015 On Parallelization of the NIS-apriori Algorithm for Data Mining
abstract
We have been developing the getRNIA software tool for data mining under uncertain information. The getRNIA software tool is powered by the NIS-Apriori algorithm, which is a variation of the well-known Apriori algorithm. This paper considers the parallelization of the NIS-Apriori algorithm, and implements a part of this algorithm based on the Apache-Spark environment. We especially apply the implemented software to two data sets, the Mammographic data set and the Mushroom data set in order to show the property of the parallelization. Even though this parallelization was not so effective for the Mammographic data set, it was much more effective for the Mushroom data set.
Mao Wu, Hiroshi Sakai
KES2
2014 An Approach Based on Rough Sets to Possibilistic Information
Michinori Nakata, Hiroshi Sakai
IPMU (3)2
2014 Apriori-Based Rule Generation in Incomplete Information Databases and Non-Deterministic Information Systems
abstract
This paper discusses issues related to incomplete information databases and considers a logical framework for rule generation. In our approach, a rule is an implication satisfying specified constraints. The term incomplete information databases covers many types of inexact data, such as non-deterministic information, data with missing values, incomplete information or interval valued data. In the paper, we start by defining certain and possible rules based on non-deterministic information. We use their mathematical properties to solve computational problems related to rule generation. Then, we reconsider the NIS-Apriori algorithm which generates a given implication if and only if it is either a certain rule or a possible rule satisfying the constraints. In this sense, NIS-Apriori is logically sound and complete. In this paper, we pay a special attention to soundness and completeness of the considered algorithmic framework, which is not necessarily obvious when switching from exact to inexact data sets. Moreover, we analyze different types of non-deterministic information corresponding to different types of the underlying attributes, i.e., value sets for qualitative attributes and intervals for quantitative attributes, and we discuss various approaches to construction of descriptors related to particular attributes within the rules' premises. An improved implementation of NIS-Apriori and some demonstrations of an experimental application of our approach to data sets taken from the UCI machine learning repository are also presented. Last but not least, we show simplified proofs of some of our theoretical results.
Hiroshi Sakai, Mao Wu, Michinori Nakata
Fundam. Informaticae1
2013 An Overview of the getRNIA System for Non-deterministic Data
abstract
In Perception-Based Computing (PBC), we face several problems, and the management of incomplete information and inexact data is an important issue to address. We have proposed a framework Rough Non-deterministic Information Analysis (RNIA) for handling tables with non-deterministic information as a kind of incomplete information. Under this framework, we coped with several rough sets-based concepts, and extended the Apriori algorithm to tables with non-deterministic information. We named this algorithm NIS -Apriori. This paper reports the overview of RNIA, NIS -Apriori and our new software getRNIA. This getRNIA gives us to generate rules through the web browser easily.
Mao Wu, Michinori Nakata, Hiroshi Sakai
KES3
2013 Division Charts as Granules and Their Merging Algorithm for Rule Generation in Nondeterministic Data
abstract
We have been proposing a framework rough Nondeterministic information analysis, which considers granular computing concepts in tables with incomplete and nondeterministic information, as well as rule generation. We have recently defined an expression named division chart with respect to an implication and a subset of objects. Each division chart takes the role of the minimum granule for rule generation, and it takes the role of contingency table in statistics. In this paper, we at first define a division chart in deterministic information systems (DISs) and clarify the relation between a division chart and a corresponding implication. We also consider a merging algorithm for two division charts and extend the relation in DISs to nondeterministic information systems. The relation gives us the foundations of rule generation in tables with nondeterministic information.
Hiroshi Sakai, Mao Wu, Michinori Nakata
Int. J. Intell. Syst.1
2012 Management of Information Incompleteness in Rough Non-deterministic Information Analysis
Hiroshi Sakai, Michinori Nakata, Dominik Slezak
IPMU (1)1
2011 Pedestrian detection and tracking using in-vehicle lidar for automotive application
abstract
This paper presents an approach to pedestrian recognition using in-vehicle Lidar. In automobile applications for reducing pedestrian-involved accident, ADAS sensors are required to provide high detection performance with environmental robustness, applicable to variety of pedestrians under the variety of driving condition. DENSO has developed the high resolution in-vehicle Lidar installing inside the cabin for higher environmental robustness, and pedestrian recognition algorithm with high tracking ability, adaptable to traffic-congestion condition seen in urban environments. Several experiments show these developments have high potential for achieving effective pedestrian safety system.
Takashi Ogawa, Hiroshi Sakai, Yasuhiro Suzuki, Kiyokazu Takagi, Katsuhiro Morikawa
Intelligent Vehicles Symposium2
2008 Rough sets approximations in data tables containing missing values
abstract
Rough sets are applied to data tables containing missing values. A new method, called a method of possible equivalence classes, is proposed. Discernibility as well as indiscernibility of missing values is considered in order to improve previous results. A family of possible equivalence classes is obtained, in which each possible equivalence class has the possibility that it is an actual one. By using the family of possible equivalence classes, we derive lower and upper approximations. The lower and the upper approximations coincide with ones obtained from methods of possible worlds.
Michinori Nakata, Hiroshi Sakai
FUZZ-IEEE2
2008 Semistationary and stationary reflection
abstract
Abstract We study the relationship between the semistationary reflection principle and stationary reflection principles. We show that for all regular cardinals λ ≥ ω2 the semistationary reflection principle in the space [λ]ω implies that every stationary subset of ≔ {α ∈ λ ∣ cf(α) = ω} reflects. We also show that for all cardinals λ ≥ ω3 the semistationary reflection principle in [λ]ω does not imply the stationary reflection principle in [λ]ω.
Hiroshi Sakai
J. Symb. Log.1
2007 Applying Rough Sets to Information Tables Containing Probabilistic Values
Michinori Nakata, Hiroshi Sakai
MDAI2
2007 On a Rough Sets Based Tool for Generating Rules from Data with Categorical and Numerical Values
Hiroshi Sakai, Kazuhiro Koba, Ryuji Ishibashi, Michinori Nakata
MDAI1
2006 Rough Sets Approximations to Possibilistic Information
abstract
Rough sets are applied to data tables containing possibilistic information. A family of weighted equivalence classes is obtained, in which each equivalence class is accompanied by a possibilistic degree to which it is an actual one. By using the family of weighted equivalence classes we can derive a lower approximation and an upper approximation. The lower approximation and the upper approximation coincide with those obtained from methods of possible worlds. Therefore, the method of weighted equivalence classes is justified.
Michinori Nakata, Hiroshi Sakai
FUZZ-IEEE2
2006 Context-Aware Information Provision to the Mobile Phone Standby Screen
abstract
Our context-aware information delivery system enables information to be provided directly to the standby screen of a user’s mobile phone. The information appears on the standby screen only while the user context matches the information context due to a function that continuously monitors the behavioral response to user context, time, location, and reference history. We conducted a four-month trial of local information provision with over 800 mobile phone users participating. Approximately 30% of them.. "positively accepted" this information provision and most users actually utilized the received information. This shows that our approach is effective for mobile ad delivery.
Takeshi Nakatsuru, Koji Murakami, Hiroshi Sakai
MDM3
2005 Autonomous Towed Vehicle for Underwater Inspection in a Port Area
abstract
This paper discusses an autonomous towed vehicle for underwater inspection in a port area, in which a sea current is so fast and complex. The autonomous towed vehicle has three different navigation modes; towed mode, autonomous mode and kite mode, to assure safe and reliable inspection in such a port area. An autonomous underwater vehicle (AUV) is employed as a towed vehicle to increase autonomy. In towed systems, it is important to monitor a towed force for preventing cable breaks and making use of it more efficiently since a towing cable plays an important role in transmitting electric signals and towing forces. In this paper, we propose a sequence for towed force estimation consisting of different navigation modes and control methods for it. In addition, the navigation control system of the autonomous towed vehicle is briefly described. Simulations to verify the towed force estimation and control methods are carried out and the results are discussed.
Jin-Kyu Choi, Hiroshi Sakai, Toshinari Tanaka
ICRA2
2005 Checking Whether or Not Rough-Set-Based Methods to Incomplete Data Satisfy a Correctness Criterion
Michinori Nakata, Hiroshi Sakai
MDAI2
2005 On a Tool for Rough Non-deterministic Information Analysis and Its Perspective for Handling Numerical Data
Hiroshi Sakai, Tetsuya Murai, Michinori Nakata
MDAI1
2003 A Framework of Rough Sets Based Rule Generation in Non-deterministic Information Systems
Hiroshi Sakai
ISMIS1
2001 Effective Procedures for Handling Possible Equivalence Relations in Non-deterministic Information Systems
Hiroshi Sakai
Fundam. Informaticae1
2000 An Algorithm for Checking Dependencies of Attributes in a Table with Non-deterministic Information: A Rough Sets Based Approach
Hiroshi Sakai, Akimichi Okuma
PRICAI1
2000 On a Theorem Prover for Variational Logic Programs with Functors Setu and Sets
abstract
We are now touching a problem how we add soft computing aspects to logic programming and we have been discussing null attribute values on logic programs. Here, we introduce two functors setu and sets into logic programs for describing indefinite attribute values explicitly. Every logic program with setu or sets has variability and tolerance in itself, namely this program expresses a set of possible definite logic programs. We call this program a variational logic program. In this paper, we show the variational logic programs and a theorem prover for them.
Hiroshi Sakai, Akimichi Okuma
Int. J. Uncertain. Fuzziness Knowl. Based Syst.1
1996 Applications of Logic Programs with Functor Set to Automated Problem Solving Under Uncertainty
Hiroshi Sakai, Akimichi Okuma
IEA/AIE1
1996 Face Recognition through Hough Transform for Irises Extraction and Projection Procedures for Parts Localization
Yoshiaki Segawa, Hiroshi Sakai, Toshio Endoh, Kazuhito Murakami, Takashi Toriu, Hiroyasu Koshimizu
PRICAI2
1995 SSM-MP: more scalability in shared-memory multi-processor
abstract
Bus-based shared-memory multi-processors (SM-MP) have successfully been used commercially, since implementation requires no drastic changes to the programming paradigm. In this paper we propose the memory structure called SSM-MP (Scalable shared-memory multi-processors), aimed to shorten the cache refill latency and to relax the bus bottle neck problem. In this machine, main memory consists of local memories dedicated to each of the processors and something called MTag. MTag is a small piece of hardware that filters out bus traffic headed to the system bus and maintains cache coherency. A popular UNIX (SVR4 ES/MP) was ported. Original OS code works well due to its natural locality. Furthermore, by allocating tasks to the local memory, we were able to reduce the system bus traffic to nearly a quarter. SSM-MP is an effective approach in building a multi-processor system with a medium number (4-32) of processors.
Shigeaki Iwasa, Shung Ho Shing, Hisashi Mogi, Hiroshi Nozuwe, Hiroo Hayashi, Osamu Wakamori, Takashi Ohmizo, Kuninori Tanaka, Hiroshi Sakai, Mitsuo Saito
ICCD9
1993 On a Framework for Logic Programming with Incomplete Information
Hiroshi Sakai
Fundam. Informaticae1
1992 An HDTV bit-rate reduction codec at the STM-1 rate of SDH
Katsutoshi Sawada, Yoshiyuki Yashima, Hiroshi Sakai
Signal Process. Image Commun.3
1988 Parallel Control Technique and Performance of an MPPM Knowledge-Base Machine
abstract
A description is given of parallel control techniques and performance evaluations by simulation for the knowledge-base machine (KBM) using the multiport page-memory (MPPM) and the unification engine (UE). Relational knowledge base retrieval requires repeated application of the unification-join (U-join) operations on term relations. It also requires each U-join to be dynamically scheduled, observing the result of the previously executed U-join. Control techniques to execute the query process of the relational knowledge base effectively in the KBM using the MPPM and the UE have been investigated. For parallel execution of coarse-grain operations, each operation is decomposed to concurrently executable fine-grain operations by partitioning input data sets. A number of features that depend on processor-allocation strategies have been identified. In particular, it was found that query processing resulting in repetitions of the retrieval operation, by a certain control strategy, increases the amount of the total data transfer to the highly parallel UEs and lowers processing efficiency.>
Hidetoshi Monoi, Yukihiro Morita, Hidenori Itoh, Hiroshi Sakai, Shigeki Shibayama
ICDE4
1985 A Hardware Pipeline Algorithm for Relational Database Operation and Its Implementation Using Dedicated Hardware
abstract
A relational database machine Delta [2] has been developed at the Institute for New Generation Computer Technology (IOOT).The main component of Delta is an RDBE (relational database engine)[3] which performs relational database operations, such as projection and join.The RDBE consists of a sorting process hardware module called the sorter, a merging process hardware module called the merger, other special hardware modules called the IN module, a data input adapter, a data output adapter, and a CPU controlling these hardware modules.A special sorting cell was developed and implemented on LSI.The sorting process is based on a two-way merge-sort algorithm [l].~ne merging process is based on a hardware pipeline algorithm.In this paper, we describe the design considerations of the RDBE and these algorithms.Then, we describe the detailed design, implementation, and a performance evaluation of the RDBE.
Shigeo Kamiya, Kazuhide Iwata, Hiroshi Sakai, Susumu Matsuda, Shigeki Shibayama, Kunio Murakami
ISCA3