Hayashi, Naoki http://orcid.org/0000-0002-6166-2572
Watanabe, Sumio
Article History
Received: 26 August 2019
Accepted: 30 January 2020
First Online: 20 February 2020
Compliance with ethical standards
:
: Conflict of interests in our research are as below: The first author is a member of NTT DATA Mathematical Systems Inc., Japan. The second author is a member of Tokyo Institute of Technology, Japan. The authors declare that they do not have any other conflicts of interest.