Incremental optimization of independent sets under the reconfiguration framework

Takehiro Ito, Haruka Mizuta, Naomi Nishimura, Akira Suzuki

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


Suppose that we are given an independent set I of a graph G, and an integer l≥ 0. Then, we are asked to find an independent set of G having the maximum size among independent sets that are reachable from I by either adding or removing a single vertex at a time such that all intermediate independent sets are of size at least l. We show that this problem is PSPACE-hard even for bounded-pathwidth graphs, and remains NP-hard for planar graphs. On the other hand, we give a linear-time algorithm to solve the problem for chordal graphs. We also study the parameterized complexity of the problem with respect to the following three parameters: the degeneracy d of an input graph, a lower bound l on the size of independent sets, and a lower bound s on the size of a solution reachable from I. We show that the problem is fixed-parameter intractable when only one of d, l, or s is taken as a parameter. On the other hand, we give a fixed-parameter algorithm when parameterized by s+ d; this result implies that the problem parameterized only by s is fixed-parameter tractable for planar graphs, and for bounded-treewidth graphs.

Original languageEnglish
Pages (from-to)1264-1279
Number of pages16
JournalJournal of Combinatorial Optimization
Issue number5
Publication statusPublished - 2022 Jul


  • Combinatorial reconfiguration
  • Graph algorithms
  • Independent set

ASJC Scopus subject areas

  • Computer Science Applications
  • Discrete Mathematics and Combinatorics
  • Control and Optimization
  • Computational Theory and Mathematics
  • Applied Mathematics


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