Researcher Database

Hitoshi Hayakawa
Faculty of Economics and Business Division of Modern Economics and Management Economic Policy
Associate Professor

Researcher Profile and Settings

Affiliation

  • Faculty of Economics and Business Division of Modern Economics and Management Economic Policy

Job Title

  • Associate Professor

URL

J-Global ID

Research Interests

  • Payment System   Financial Network   Asset Bubble   Monetary Economics   

Research Areas

  • Humanities & social sciences / Economic policy

Academic & Professional Experience

  • 2019/04 - Today Hokkaido University Faculty of Economics and Business Associate professor
  • 2015/02 - 2019/03 Hokkaido University Creative Research Institution (Faculty of Economics and Business) Assistant professor
  • 2013/04 - 2015/02 The University of Tokyo Graduate school of Economics Assistant professor

Research Activities

Published Papers

  • Naoshi Doi, Hitoshi Hayakawa
    INTERNATIONAL JOURNAL OF THE ECONOMICS OF BUSINESS 27 (2) 303 - 320 1357-1516 2020/05 [Refereed]
     
    This paper reviews existing studies investigating online communication on products and services, also known as, electronic word-of-mouth (eWOM). The first half of the paper summaries what is known about eWOM in the literature. Existing studies largely relate to the marketing field and are generally conducted from a marketing firms' point of view. To investigate eWOM from the perspective of social welfare, the latter half of the paper discusses theoretical frameworks of economics that are potentially applicable to the context of eWOM, especially focusing on theories about social learning and signaling. We discuss implications obtained by applying these theories to eWOM and outline possible directions for future research.
  • Hitoshi Hayakawa
    COMPUTATIONAL ECONOMICS 55 (1) 253 - 301 0927-7099 2020/01 [Refereed][Not invited]
     
    This study investigates the amount of liquidity that is necessary to settle a given network of financial obligations. In our analysis, we assume sequential settlement, which is standard in real-world interbank settlement systems, instead of simultaneous settlement, which is typically assumed in relevant research. We develop a graph-theoretic model and apply a flow network technique to investigate how the interconnected feature could affect the required liquidity. Our main contribution is to show that the effect of the interconnected feature is characterized with our original concepts regarding "twist" properties-arc-twisted and vertex-twisted-that are defined on the basis of the concept of "cycles." Each of the "twist" properties refers to certain inconsistency in the dynamics of settlements. The characterization provides a consistent and fundamental perspective of how a hub or other network structures affect the required liquidity. We further investigate the quantitative implications of the "twist" properties for real-world networks of obligations by examining networks with clustered structures and small-world structures. We show that "twist" properties have non-linear effects on the required liquidity against an increase in the amount of obligations.
  • Hitoshi Hayakawa, Toshimasa Ishii, Hirotaka Ono, Yushi Uno
    DISCRETE APPLIED MATHEMATICS 265 86 - 103 0166-218X 2019/07 [Refereed][Not invited]
     
    In the economic activities, the central bank has an important role to cover payments of banks, when they are short of funds to clear their debts. For this purpose, the central bank timely puts funds so that the economic activities go smooth. Since payments in this mechanism are processed sequentially, the total amount of funds put by the central bank critically depends on the order of the payments. Then an interest goes to the amount to prepare if the order of the payments can be controlled by the central bank, or if it is determined under the worst case scenario. This motivates us to introduce a brand-new problem, which we call the settlement fund circulation problem. The problems are formulated as follows: Let G = (V, A) be a directed multigraph with a vertex set V and an arc set A. Each arc a is an element of A is endowed debt d(a) >= 0, and the debts are settled sequentially under a sequence pi of arcs. Each vertex V is an element of V is put fund in the amount of p(pi)(v) >= 0 under the sequence. The minimum maximum settlement fund circulation problem (MIN-SFC/MAx-SFC) in a given graph G with debts d : A -> R+ U {0} asks to find a bijection pi : A -> {1,2, ..., vertical bar A vertical bar} that minimizes/maximizes the total funds Sigma(v is an element of V) P-pi(v). In this paper, we show that both MIN-SFC and MAX-SFC are NP-hard; in particular, MIN-SFC is (I) strongly NP-hard even if G is (i) a multigraph with vertical bar V vertical bar = 2 or (ii) a simple graph with treewidth at most two, and is (II) (not necessarily strongly) NP-hard for simple trees of diameter four, while it is solvable in polynomial time for stars. Also, we identify several polynomial time solvable cases for both problems. (C) 2019 Elsevier B.V. All rights reserved.
  • Hitoshi Hayakawa, Susumu Imai, Kazuko Nakata
    JAPANESE ECONOMIC REVIEW 69 (3) 324 - 339 1352-4739 2018/09 [Refereed]
     
    In this paper, we survey the empirical analysis of brands. The difficulty in this area of research is that even though a brand is easily identifiable, its economic roles are not directly observable. We first discuss methods where the effect of a brand is measured as the unobservable component of sales or price of a product, which researchers recover as a residual of the sales or price regression. We then describe the approaches to estimate the various roles of brands, such as providing information and increasing the utility of consumption. Finally, we provide examples of research that highlight the role of brands in exploiting the irrationality of consumers for profit.
  • Hitoshi Hayakawa
    JOURNAL OF ECONOMIC INTERACTION AND COORDINATION 13 (1) 9 - 50 1860-711X 2018/04 [Refereed][Not invited]
     
    This study investigates whether and how central clearing influences the overall liquidity needs in a network of financial obligations. Utilizing the approach of flow network theory, we show that the effect of adding a central clearing counterparty (CCP) is decomposed into two effects: central routing, and central netting effects. Each effect can produce different liquidity needs according to different liquidity scenarios. The analysis indicates that adding a CCP in times of financial distress successfully reduces the overall liquidity needs if and only if the netting efficiency of the CCP is sufficiently high. Furthermore, once the economy is no longer in financial distress, higher netting efficiency of the CCP could conversely increase the overall liquidity needs. The results have implications for the effectiveness of CCPs in mitigating systemic risk in times of financial distress, and their operating costs once the distress has passed.
  • Hitoshi Hayakawa, Toshimasa Ishii, Hirotaka Ono, Yushi Uno
    Leibniz International Proceedings in Informatics, LIPIcs 92 1868-8969 2017/12/01 [Refereed][Not invited]
     
    In the economic activities, the central bank has an important role to cover payments of banks, when they are short of funds to clear their debts. For this purpose, the central bank timely puts funds so that the economic activities go smooth. Since payments in this mechanism are processed sequentially, the total amount of funds put by the central bank critically depends on the order of the payments. Then an interest goes to the amount to prepare if the order of the payments can be controlled by the central bank, or if it is determined under the worst case scenario. This motivates us to introduce a brand-new problem, which we call the settlement fund circulation problem. The problems are formulated as follows: Let G = (V,A) be a directed multigraph with a vertex set V and an arc set A. Each arc a 2 A is endowed debt d(a) 0, and the debts are settled sequentially under a sequence of arcs. Each vertex v 2 V is put fund in the amount of p(v) 0 under the sequence. The minimum/maximum settlement fund circulation problem (Min-SFC/Max-SFC) in a given graph G with debts d : A ! R+ [ {0} asks to find a bijection : A {1, 2,. . . , |A|} that minimizes/maximizes the total funds P v2V p(v). In this paper, we show that both Min-SFC and Max-SFC are NP-hard in particular, Min-SFC is (I) strongly NP-hard even if G is (i) a multigraph with |V | = 2 or (ii) a simple graph with treewidth at most two, and is (II) (not necessarily strongly) NP-hard for simple trees of diameter four, while it is solvable in polynomial time for stars. Also, we identify several polynomial time solvable cases for both problems.

Research Grants & Projects

  • Institutional Design for Digital Economy
    Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    Date (from‐to) : 2020/04 -2024/03 
    Author : 松島 斉, 尾山 大輔, 萱場 豊, 山本 裕一, 佐野 隆司, 中島 大輔, 安田 洋祐, 早川 仁, 岡崎 哲二
  • 貨幣的一般均衡モデルにおける資産バブルを中心とした分析
    日本学術振興会:科学研究費助成事業 若手研究
    Date (from‐to) : 2020/04 -2024/03 
    Author : 早川 仁

Educational Activities

Teaching Experience

  • Seminar of Modern Economics and Management I
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 経済学院
  • Seminar of Modern Economics and Management II
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 経済学院
  • Special Study of Financial Economics A
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 経済学院
  • Special Study of Financial Economics B
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 経済学院
  • Seminar I
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 経済学部
    キーワード : 貨幣、決済、金融、暗号通貨、銀行システム、バブル、金融危機
  • Seminar II
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 経済学部
    キーワード : 貨幣、決済、金融、暗号通貨、銀行システム、バブル、金融危機
  • Seminar III
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 経済学部
    キーワード : 貨幣、決済、金融、暗号通貨、銀行システム、バブル、金融危機
  • Seminar IV
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 経済学部
    キーワード : 貨幣、決済、金融、暗号通貨、銀行システム、バブル、金融危機
  • Seminar V
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 経済学部
    キーワード : 貨幣、決済、金融、暗号通貨、銀行システム、バブル、金融危機
  • Seminar VI
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 経済学部
    キーワード : 貨幣、決済、金融、暗号通貨、銀行システム、バブル、金融危機
  • Seminar VII
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 経済学部
    キーワード : 貨幣、決済、金融、暗号通貨、銀行システム、バブル、金融危機
  • Seminar VIII
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 経済学部
    キーワード : 貨幣、決済、金融、暗号通貨、銀行システム、バブル、金融危機
  • Modern Japanese Society IID
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 現代日本学プログラム課程
    キーワード : 貨幣、暗号通貨、手形、信用、物価、金利、銀行、中央銀行、決済、金融仲介、金融政策、証券市場、資金調達、バブル、金融危機
  • Topics in Advanced Economic Analysis I
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 経済学部
    キーワード : 貨幣、暗号通貨、手形、信用、物価、金利、銀行、中央銀行、決済、金融仲介、金融政策、証券市場、資金調達、バブル、金融危機
  • English Seminar
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : 貨幣、暗号通貨、Bitcoin, ブロックチェーン、マイニング、Proof of Work
  • Financial Economics
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 経済学部
    キーワード : 貨幣、暗号通貨、手形、信用、物価、金利、銀行、中央銀行、決済、金融仲介、金融政策、証券市場、資金調達、バブル、金融危機
  • Monetary Policy
    開講年度 : 2021
    課程区分 : 専門職大学院
    開講学部 : 公共政策学教育部


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