A graph class 𝒞 is monadically dependent if one cannot interpret all graphs in colored graphs from 𝒞 using a fixed first-order interpretation. We prove that monadically dependent classes can be exactly characterized by the following property, which we call flip-separability: for every r ∈ ℕ, ε > 0, and every graph G ∈ 𝒞 equipped with a weight function on vertices, one can apply a bounded (in terms of 𝒞,r,ε) number of flips (complementations of the adjacency relation on a subset of vertices) to G so that in the resulting graph, every radius-r ball contains at most an ε-fraction of the total weight. On the way to this result, we introduce a robust toolbox for working with various notions of local separations in monadically dependent classes.
@InProceedings{bonnet_et_al:LIPIcs.ICALP.2025.147, author = {Bonnet, \'{E}douard and Braunfeld, Samuel and Eleftheriadis, Ioannis and Geniet, Colin and M\"{a}hlmann, Nikolas and Pilipczuk, Micha{\l} and Przybyszewski, Wojciech and Toru\'{n}czyk, Szymon}, title = {{Separability Properties of Monadically Dependent Graph Classes}}, booktitle = {52nd International Colloquium on Automata, Languages, and Programming (ICALP 2025)}, pages = {147:1--147:19}, 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.2025.147}, URN = {urn:nbn:de:0030-drops-235246}, doi = {10.4230/LIPIcs.ICALP.2025.147}, annote = {Keywords: Structural graph theory, Monadic dependence} }
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