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On Time-Memory Tradeoffs for Maximal Palindromes with Wildcards and k-Mismatches

Authors Amihood Amir , Ayelet Butman, Michael Itzhaki , Dina Sokol

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ACM Subject Classification
  • Theory of computation → Design and analysis of algorithms
Keywords
  • Wildcards
  • Mismatches
  • Palindrome

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Abstract

This paper addresses the problem of identifying palindromic factors in texts that include wildcards - special characters that match all others. These symbols challenge many classical algorithms, as numerous combinatorial properties are not satisfied in their presence. We apply existing wildcard-LCE techniques to obtain a continuous time-memory tradeoff, and present the first non-trivial linear-space algorithm for computing all maximal palindromes with wildcards, improving the best known time-memory product in certain parameter ranges. Our main results are algorithms to find and approximate all maximal palindromes in a given text. We also generalize both methods to the k-mismatches setting, with or without wildcards.

Cite As Get BibTex

Amihood Amir, Ayelet Butman, Michael Itzhaki, and Dina Sokol. On Time-Memory Tradeoffs for Maximal Palindromes with Wildcards and k-Mismatches. In 37th Annual Symposium on Combinatorial Pattern Matching (CPM 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 369, pp. 18:1-18:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026) https://doi.org/10.4230/LIPIcs.CPM.2026.18

Author Details

Amihood Amir
  • Department of Computer Science, Bar-Ilan University, Ramat Gan, Israel
  • College of Computing, Georgia Tech, Atlanta, GA, USA
Ayelet Butman
  • Department of Computer Science, Holon Institute of Technology, Israel
Michael Itzhaki
  • Department of Computer Science, Bar-Ilan University, Ramat Gan, Israel
Dina Sokol
  • Department of Computer and Information Science, Brooklyn College, NY, USA

Funding

  • Amir, Amihood: Partially supported by ISF grant 168/23 and BSF grant 2018-141.
  • Itzhaki, Michael: Partially supported by ISF grant 168/23.

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