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IEICE TRANSACTIONS on Information

DAG-Pathwidth: Graph Algorithmic Analyses of DAG-Type Blockchain Networks

Shoji KASAHARA, Jun KAWAHARA, Shin-ichi MINATO, Jumpei MORI

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Summary :

This paper analyzes a blockchain network forming a directed acyclic graph (DAG), called a DAG-type blockchain, from the viewpoint of graph algorithm theory. To use a DAG-type blockchain, NP-hard graph optimization problems on the DAG are required to be solved. Although various problems for undirected and directed graphs can be efficiently solved by using the notions of graph parameters, these currently known parameters are meaningless for DAGs, which implies that it is hopeless to design efficient algorithms based on the parameters for such problems. In this work, we propose a novel graph parameter for directed graphs called a DAG-pathwidth, which represents the closeness to a directed path. This is an extension of the pathwidth, a well-known graph parameter for undirected graphs. We analyze the features of the DAG-pathwidth and prove that computing the DAG-pathwidth of a DAG (directed graph in general) is NP-complete. Finally, we propose an efficient algorithm for a variant of the maximum k-independent set problem for the DAG-type blockchain when the DAG-pathwidth of the input graph is small.

Publication
IEICE TRANSACTIONS on Information Vol.E106-D No.3 pp.272-283
Publication Date
2023/03/01
Publicized
2022/12/22
Online ISSN
1745-1361
DOI
10.1587/transinf.2022FCP0007
Type of Manuscript
Special Section PAPER (Special Section on Foundations of Computer Science — Foundations of Computer Science Supporting the Information Society —)
Category

Authors

Shoji KASAHARA
  Nara Institute of Science and Technology
Jun KAWAHARA
  Kyoto University
Shin-ichi MINATO
  Kyoto University
Jumpei MORI
  Kyoto University

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