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Hirokazu Anai

Possible papers associated with this exact author name in Arrow. This page groups case-insensitive exact name matches and is not a full identity disambiguation profile.

4 papers
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4

AAAI Conference 2018 Conference Paper

Learning Multi-Way Relations via Tensor Decomposition With Neural Networks

  • Koji Maruhashi
  • Masaru Todoriki
  • Takuya Ohwa
  • Keisuke Goto
  • Yu Hasegawa
  • Hiroya Inakoshi
  • Hirokazu Anai

How can we classify multi-way data such as network traffic logs with multi-way relations between source IPs, destination IPs, and ports? Multi-way data can be represented as a tensor, and there have been several studies on classification of tensors to date. One critical issue in the classification of multi-way relations is how to extract important features for classification when objects in different multi-way data, i. e. , in different tensors, are not necessarily in correspondence. In such situations, we aim to extract features that do not depend on how we allocate indices to an object such as a specific source IP; we are interested in only the structures of the multi-way relations. However, this issue has not been considered in previous studies on classification of multi-way data. We propose a novel method which can learn and classify multi-way data using neural networks. Our method leverages a novel type of tensor decomposition that utilizes a target core tensor expressing the important features whose indices are independent of those of the multi-way data. The target core tensor guides the tensor decomposition into more effective results and is optimized in a supervised manner. Our experiments on three different domains show that our method is highly accurate, especially on higher order data. It also enables us to interpret the classification results along with the matrices calculated with the novel tensor decomposition.

AAMAS Conference 2016 Conference Paper

Simplifying Urban Network Security Games with Cut-Based Graph Contraction

  • Hiroaki Iwashita
  • Kotaro Ohori
  • Hirokazu Anai
  • Atsushi Iwasaki

The scalability of the algorithm for solving urban network security games, which is an important challenge concerning security game problems, was improved. State-of-the-art solvers have been scaled up to handle real-world networks with tens of thousands of edges; however, it can take days or more when the inputs are varied. Since they do not essentially overcome exponential growth of the strategy space with increasing graph size, an approach, which can be combined with previous ones, is proposed. In particular, a practical approach of simplifying the graphs so that they can be handled within a realistic time is devised and tested. The key idea behind this approach is to restrict the defender’s pure strategies to potential ones before calculating an equilibrium solution. The restriction can be tightened for faster computation and loosened for better solution. The following three techniques for computing an optimal solution to the restricted game are proposed and evaluated: (i) contraction of the network based on the restriction, (ii) compact formulation of the optimization problem using weighted edges in place of multiple edges, and (iii) efficient solution using a mixed-integer quadratic programming oracle. They can naturally cope with an extension of the game to one taking width of the roads into account. Furthermore, a heuristic algorithm of finding effective restriction of the game is also proposed.

AAAI Conference 2014 Conference Paper

The Most Uncreative Examinee: A First Step toward Wide Coverage Natural Language Math Problem Solving

  • Takuya Matsuzaki
  • Hidenao Iwane
  • Hirokazu Anai
  • Noriko Arai

We report on a project aiming at developing a system that solves a wide range of math problems written in natural language. In the system, formal analysis of natural language semantics is coupled with automated reasoning technologies including computer algebra, using logic as their common language. We have developed a prototype system that accepts as its input a linguistically annotated problem text. Using the prototype system as a reference point, we analyzed real university entrance examination problems from the viewpoint of end-to-end automated reasoning. Further, evaluation on entrance exam mock tests revealed that an optimistic estimate of the system’s performance already matches human averages on a few test sets.

TCS Journal 2013 Journal Article

An effective implementation of symbolic–numeric cylindrical algebraic decomposition for quantifier elimination

  • Hidenao Iwane
  • Hitoshi Yanami
  • Hirokazu Anai
  • Kazuhiro Yokoyama

With many applications in engineering and scientific fields, quantifier elimination (QE) has received increasing attention. Cylindrical algebraic decomposition (CAD) is used as a basis for a general QE algorithm. In this paper we present an effective symbolic–numeric cylindrical algebraic decomposition (SNCAD) algorithm for QE incorporating several new devices, which we call “quick tests”. The simple quick tests are run beforehand to detect an unnecessary procedure that might be skipped without violating the correctness of results and they thus considerably reduce the computing time. The effectiveness of the SNCAD algorithm is examined in a number of experiments including practical engineering problems, which also reveal the quality of the implementation. Experimental results show that our implementation has significantly improved efficiency compared with our previous work.

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