A graph G = (V,E) is a k-leaf power if there is a tree T whose leaves are the vertices of G, with the property that a pair of distinct leaves u and v share an edge in G if and only if they are distance at most k apart in T. For k ≤ 4, it is known that there exists a finite set F_k of graphs such that the class ℒ(k) of k-leaf power graphs is characterized as the set of strongly chordal graphs that do not contain any graph in F_k as an induced subgraph. We prove no such characterization holds for k ≥ 5. That is, for any k ≥ 5, there is no finite set F_k of graphs such that ℒ(k) is equivalent to the set of strongly chordal graphs that do not contain as an induced subgraph any graph in F_k.
@InProceedings{duprelatour_et_al:LIPIcs.ICALP.2025.72, author = {Dupr\'{e} la Tour, Max and Lafond, Manuel and Ndiaye, Ndiam\'{e} and Vetta, Adrian}, title = {{k-Leaf Powers Cannot Be Characterized by a Finite Set of Forbidden Induced Subgraphs for k ≥ 5}}, booktitle = {52nd International Colloquium on Automata, Languages, and Programming (ICALP 2025)}, pages = {72:1--72:17}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-372-0}, ISSN = {1868-8969}, year = {2025}, volume = {334}, editor = {Censor-Hillel, Keren and Grandoni, Fabrizio and Ouaknine, Jo\"{e}l and Puppis, Gabriele}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICALP.2025.72}, URN = {urn:nbn:de:0030-drops-234499}, doi = {10.4230/LIPIcs.ICALP.2025.72}, annote = {Keywords: Leaf Powers, Forbidden Graph Characterizations, Strongly Chordal Graphs} }
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