{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,26]],"date-time":"2026-03-26T20:10:22Z","timestamp":1774555822193,"version":"3.50.1"},"reference-count":0,"publisher":"The Electronic Journal of Combinatorics","issue":"1","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Electron. J. Combin."],"abstract":"<jats:p>For an integer $t\\geq 4$, a $t$-sun is a graph obtained from a $t$-vertex cycle $C$ by adding a degree-one neighbor for each vertex of $C$. Trotignon asked whether every triangle-free graph of sufficiently large chromatic number has an induced subgraph that is a $t$-sun for some $t\\geq 4$. This remains open, but we show that every triangle-free graph of chromatic number at least $48$ has an induced subgraph that is either a $t$-sun for some $t\\geq 5$, or a $4$-sun with a single degree-one vertex deleted. In fact, we prove that for all $\\ell\\geq 5$, there exists $c=c(\\ell)\\in \\mathbb{N}$ such that every triangle-free graph of chromatic number at least $c$ has an induced subgraph that is either a $t$-sun for some $t\\geq \\ell$, or a $4$-sun with a single degree-one vertex deleted.<\/jats:p>","DOI":"10.37236\/14443","type":"journal-article","created":{"date-parts":[[2026,3,26]],"date-time":"2026-03-26T19:48:25Z","timestamp":1774554505000},"source":"Crossref","is-referenced-by-count":0,"title":["Suns in Triangle-Free Graphs of Large Chromatic Number"],"prefix":"10.37236","volume":"33","author":[{"given":"Sepehr","family":"Hajebi","sequence":"first","affiliation":[]},{"given":"Sophie","family":"Spirkl","sequence":"additional","affiliation":[]}],"member":"23455","published-online":{"date-parts":[[2026,3,27]]},"container-title":["The Electronic Journal of Combinatorics"],"original-title":[],"link":[{"URL":"https:\/\/www.combinatorics.org\/ojs\/index.php\/eljc\/article\/download\/v33i1p55\/pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/www.combinatorics.org\/ojs\/index.php\/eljc\/article\/download\/v33i1p55\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,3,26]],"date-time":"2026-03-26T19:48:25Z","timestamp":1774554505000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.combinatorics.org\/ojs\/index.php\/eljc\/article\/view\/v33i1p55"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,3,27]]},"references-count":0,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2026,1,9]]}},"URL":"https:\/\/doi.org\/10.37236\/14443","relation":{},"ISSN":["1077-8926"],"issn-type":[{"value":"1077-8926","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,3,27]]},"article-number":"P1.55"}}