Abstract.

Given a graph \(H\), we say that an edge-colored graph \(G\) is \(H\)-rainbow saturated if it does not contain a rainbow copy of \(H\), but the addition of any nonedge in any color creates a rainbow copy of \(H\). The rainbow saturation number \(\mathrm{rsat}(n,H)\) is the minimum number of edges among all \(H\)-rainbow saturated edge-colored graphs on \(n\) vertices. We prove that for any nonempty graph \(H\), the rainbow saturation number is linear in \(n\), thus proving a conjecture of Girão, Lewis, and Popielarz. In addition, we give an improved upper bound on the rainbow saturation number of the complete graph, disproving a second conjecture of Girão, Lewis, and Popielarz.

Keywords

  1. saturation
  2. rainbow
  3. edge-coloring

MSC codes

  1. 05C35

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Acknowledgment.

We would like to thank the anonymous referees for their helpful comments.

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Information & Authors

Information

Published In

cover image SIAM Journal on Discrete Mathematics
SIAM Journal on Discrete Mathematics
Pages: 1239 - 1249
ISSN (online): 1095-7146

History

Submitted: 19 April 2023
Accepted: 21 December 2023
Published online: 8 April 2024

Keywords

  1. saturation
  2. rainbow
  3. edge-coloring

MSC codes

  1. 05C35

Authors

Affiliations

Mathematics Institute, University of Warwick, Coventry, CV4 7AL, UK.
School of Mathematics, University of Bristol, Bristol, BS8 1UG, UK, and Heilbronn Institute for Mathematical Research, Bristol, BS8 1UG, UK.
Shoham Letzter
Department of Mathematics, University College London, Gower Street, London, WC1E 6BT, UK.
Natasha Morrison
Department of Mathematics and Statistics, University of Victoria, Victoria V8W 2Y2, BC, Canada.
Shannon Ogden
Department of Mathematics and Statistics, University of Victoria, Victoria V8W 2Y2, BC, Canada.

Funding Information

Funding: The first author’s research was supported by a PIMS postdoctoral fellowship. The third author’s research was supported by the Royal Society. The fourth author’s research was supported by NSERC Discovery Grant RGPIN-2021-02511 and NSERC Early Career Supplement DGECR-2021-00047. The fifth author was supported by NSERC CGS M.

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