Hirotsugu Kakugawa’s research while affiliated with Ryukoku University and other places

What is this page?


This page lists works of an author who doesn't have a ResearchGate profile or hasn't added the works to their profile yet. It is automatically generated from public (personal) data to further our legitimate goal of comprehensive and accurate scientific recordkeeping. If you are this author and want this page removed, please let us know.

Publications (151)


A Visibility vs. Memory Trade-Off for Stand-Up Indulgent Gathering on Lines
  • Chapter

May 2025

·

Hirotsugu Kakugawa

·

·

[...]

·

Sébastien Tixeuil

Examples of IS, MIS and 1‐MIS. (A) Not IS. (B) IS. (C) MIS. (D) 1‐MIS.
A state‐flip transaction in SS1MISD3. (A) Ready to initiate. (B) Rule A4 by Pi$$ {P}_i $$. (C) Rule A6 by Pj$$ {P}_j $$. (D) Rule A6 by Pj′$$ {P}_{j^{\prime }} $$. (E) Rule A5 by Pi$$ {P}_i $$.
1‐MIS (Va$$ {V}_a $$) and the maximum IS (Vb$$ {V}_b $$) of K2,n−2$$ {K}_{2,n-2} $$.
A self‐stabilizing distributed algorithm for the 1‐MIS problem under the distance‐3 model
  • Article
  • Publisher preview available

September 2024

·

3 Reads

Fault‐tolerance and self‐organization are critical properties in modern distributed systems. Self‐stabilization is a class of fault‐tolerant distributed algorithms which has the ability to recover from any kind and any finite number of transient faults and topology changes. In this article, we propose a self‐stabilizing distributed algorithm for the 1‐MIS problem under the unfair central daemon assuming the distance‐3 model. Here, in the distance‐3 model, each process can refer to the values of local variables of processes within three hops. Intuitively speaking, the 1‐MIS problem is a variant of the maximal independent set (MIS) problem with improved local optimizations. The time complexity (convergence time) of our algorithm is O(n) O(n) steps and the space complexity is O(logn)O(logn) O\left(\log n\right) bits, where n n is the number of processes. Finally, we extend the notion of 1‐MIS to p p ‐MIS for each nonnegative integer p p , and compare the set sizes of p p ‐MIS (p=0,1,2,…p=0,1,2, p=0,1,2,\dots ) and the maximum independent set.

View access options



Examples of minimal minus (L,K,Z)$$ \left(L,K,Z\right) $$‐dominating functions. (The parenthesized number is the local summation of f$$ f $$.)
A self‐stabilizing distributed algorithm for the bounded lattice domination problems under the distance‐2 model

September 2023

·

26 Reads

The domination problem is one of the fundamental graph problems, and there are many variations. In this article, we propose a new problem called the minus (L,K,Z)(L,K,Z) \left(L,K,Z\right) ‐domination problem where L,K L,K , and Z Z are integers such that L≤−1L1 L\le -1 , K≥1K1 K\ge 1 , and Z≥1Z1 Z\ge 1 . The problem is to assign a value from L,L+1,…,0,…,K−1,KL,L+1,,0,,K1,K L,L+1,\dots, 0,\dots, K-1,K for each vertex in a graph such that the local summation of values is greater than or equal to Z Z . We also propose a framework named the bounded lattice domination for a class of domination problems, including the minus (L,K,Z)(L,K,Z) \left(L,K,Z\right) ‐domination problem. Then, we present a self‐stabilizing distributed algorithm under the distance‐2 model for the bounded lattice domination. Here, self‐stabilization is a class of fault‐tolerant distributed algorithms that tolerate transient faults. The time complexity for convergence is O(n) O(n) , where n n is the number of processes in a network if the cardinality of the domain of process values is finite and constant. Otherwise, the time complexity for convergence is O(n2)O(n2) O\left({n}^2\right) .



Invited Paper: One Bit Agent Memory is Enough for Snap-Stabilizing Perpetual Exploration of Cactus Graphs with Distinguishable Cycles

November 2022

·

12 Reads

Lecture Notes in Computer Science

This paper considers perpetual exploration of anonymous cactus graphs with distinguishable cycles by a single mobile agent under the restriction that nodes have no storage (e.g., whiteboards or token places). A cactus with distinguishable cycles allows the agent to distinguish at each node the two incident edges contained in each cycle from other incident edges. This paper introduces the concept of snap-stabilization into the perpetual exploration and shows that snap-stabilizing perpetual exploration is possible when the agent has one-bit persistent memory. The exploration time of the presented algorithm exactly matches a trivial lower bound. This paper also shows the necessity of one-bit agent memory by showing that any oblivious (or memory-less) agent cannot explore a cactus graph even when it has only a single distinguishable cycle. Finally, this paper shows that snap-stabilizing perpetual exploration by an oblivious agent is possible when a cactus graph with distinguishable cycles has a sense of direction.KeywordsMobile agentGraph explorationCactus graphSnap-stabilization




A Self-Stabilizing Distributed Algorithm for the Generalized Dominating Set Problem With Safe Convergence

March 2022

·

10 Reads

·

2 Citations

The Computer Journal

A self-stabilizing distributed algorithm is guaranteed eventually to reach and stay at a legitimate configuration regardless of the initial configuration of a distributed system. In this paper, we propose the generalized dominating set problem, which is a generalization of the dominating set and k-redundant dominating set problems. In the generalized dominating set we propose in this paper, each node PiP_{i} is given its set of domination wish sets, and a generalized dominating set is a set of nodes such that each node is contained in the set or has a wish set in which all its members are in the set. We propose a self-stabilizing distributed algorithm for finding a minimal generalized dominating set in an arbitrary network under the unfair distributed daemon. The proposed algorithm converges in O(n3m)O(n^{3}m) steps and O(n) rounds, where n (resp., m) is the number of nodes (resp., edges). Furthermore, it has the safe convergence property with safe convergence time in O(1) rounds. The space complexity of the proposed algorithm is O(Δlogn)O(\Delta \log n) bits per node, where Δ\Delta is the maximum degree of nodes.


Citations (52)


... To reflect that transfers may be realized using different agreement mechanisms (e.g., a blockchain or a payment channel built on-top of a blockchain), we say that an ATG specifies atomic transfers in a heterogenous blockchain ecosystem (short HBE). Such general ATGs serve as a specification format for applications beyond multi-hop payments, including crowdfunding [7], [8], where several users atomically fund a certain receiver; rebalancing in PCNs [9]- [14], where a cycle payment is used to redistribute balances among the involved PCs; or atomic swaps [15]- [21], where users intent to atomically exchange several assets of their interest held at different cryptocurrencies; and beyond. ...

Reference:

Atomic Transfer Graphs: Secure-by-design Protocols for Heterogeneous Blockchain Ecosystems
Atomic Cross-Chain Swaps with Improved Space, Time and Local Time Complexities
  • Citing Article
  • April 2023

Information and Computation

... An algorithm that works on general networks is proposed by Tanaka et al. 10 under the weakly-fair distributed daemon. Their algorithm uses the loop composition 11 to simplify the design and verification of their algorithm. ...

A Self-stabilizing 1-maximal Independent Set Algorithm
  • Citing Article
  • January 2021

Journal of Information Processing

... While all the above work on the total gathering problem and the g-partial gathering problem are considered in static graphs where a network topology does not change during an execution, recently many problems involving agents have been studied in dynamic graphs, where a topology changes during an execution. For example, the total gathering problem [19], the exploration problem [20,21], the compact configuration problem [22], the patrolling problem [23], and the uniform deployment problem [24] are considered in dynamic graphs. In [19], Luna et al. considered the total gathering problem in 1-interval connected rings, that is, one of the links in a ring may be missing at each time step. ...

Exploration of dynamic tori by multiple agents
  • Citing Article
  • January 2021

Theoretical Computer Science

... The state-of-the-art results discussed in the previous two paragraphs were the culmination of the long series of work [1,3,4,6,10,15,17,16,18,20,21,22,24,26,31,32,34]. The majority of works considered the faulty-free case, except [4,27,28] which considered Byzantine faults (where agents might act arbitrarily) and [3,4,6,29] considered crash faults (where some agents might stop working permanently at any time). ...

Efficient Dispersion of Mobile Agents without Global Knowledge
  • Citing Chapter
  • November 2020

Lecture Notes in Computer Science

... Simultaneously, Alistarh and Gelashvili [4] presented a protocol using O(log 3 n) states and achieving O(log 3 n) expected time (ICALP 2015). Subsequent work [1,13,2,23,24,31] successively improved these upper bounds from 2017 to 2019. Finally, Berenbrink, Giakkoupis, and Kling [12] presented an O(log log n)-state and O(log n)-expected-time protocol (STOC 2020). ...

Time-Optimal Leader Election in Population Protocols

IEEE Transactions on Parallel and Distributed Systems

... As related work, Shibata et al. considered the g-partial gathering problem in rings [14,15,16], trees [17], and arbitrary networks [18]. In [14,15], they considered it in unidirectional ring networks with whiteboards (or memory spaces that agents can read and write) at nodes. ...

Move-optimal partial gathering of mobile agents without identifiers or global knowledge in asynchronous unidirectional rings
  • Citing Article
  • April 2020

Theoretical Computer Science

... While the majority work on population protocols studies the setting where every pair of agents can interact, quite a few studies deal with a more general setting: interactions may occur between restricted pairs of agents, introducing a interaction graph G = (V, E), where V represents the set of agents and E the set of interactable pairs. SS-LE and its weaken variant have been also studied in rings [21,17,36,37], regular graphs [18], and general graphs [21,33,32,35,26]. ...

Loosely Stabilizing Leader Election on Arbitrary Graphs in Population Protocols without Identifiers or Random Numbers
  • Citing Article
  • March 2020

IEICE Transactions on Information and Systems

... Recently, Poudel and Sharma 13 improved the time complexity of uniform deployment on grids for robots without light colors (i.e., oblivious robots). A separate research track considered the uniform deployment problem in ring networks for another mobile entity called mobile agents, [17][18][19] which have persistent memory but cannot observe others' positions unless they are located on the same node. Like the aforementioned works, although uniform deployment has been considered in various settings, to the best of our knowledge, it was not considered in graphs other than rings or grids. ...

Space-efficient uniform deployment of mobile agents in asynchronous unidirectional rings
  • Citing Article
  • February 2020

Theoretical Computer Science

... Self-stabilizing distributed algorithms for the local (group) mutual exclusion problem are proposed in [6][7][8]. Various generalized versions of mutual exclusion have been studied extensively, e.g., l-mutual exclu-sion [16,17], mutual inclusion [18], 1 l-mutual inclusion [18], and critical section problem [19,20]. ...

A self‐stabilizing distributed algorithm for the local (1,|Ni|)‐critical section problem