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Chromatic symmetric functions and H-free graphs

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Abstract

Using a graph and its colorings we can define a chromatic symmetric function. Stanley’s celebrated conjecture about the e-positivity of claw-free incomparability graphs has seen several related results, including one showing (\(claw, P_4\))-free graphs are e-positive. Here we extend the claw-free idea to general graphs and consider the e-positivity question for H-free graphs where \(H = \{claw, F\}\) and \(H=\){claw, F, co-F}, where F is a four-vertex graph. We settle the question for all cases except \(H=\){claw, co-diamond}, and we provide some partial results in that case.

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Acknowledgements

This work was supported by the Canadian Tri-Council Research Support Fund. The 1st and 2nd authors (A.M. Hamel and C.T. Hoàng) were each supported by individual NSERC Discovery Grants. The 3rd author (J.E. Tuero) was supported by an NSERC Undergraduate Student Research Award (USRA).

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  1. Department of Physics and Computer Science, Wilfrid Laurier University, Waterloo, ON, Canada

    Angèle M. Hamel, Chính T. Hoàng & Jake E. Tuero

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  1. Angèle M. Hamel
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  2. Chính T. Hoàng
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  3. Jake E. Tuero
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Correspondence to Angèle M. Hamel.

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Hamel, A.M., Hoàng, C.T. & Tuero, J.E. Chromatic symmetric functions and H-free graphs. Graphs and Combinatorics 35, 815–825 (2019). https://doi.org/10.1007/s00373-019-02034-1

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  • DOI: https://doi.org/10.1007/s00373-019-02034-1

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