<?xml version="1.0" encoding="UTF-8"?>
<OAI-PMH xmlns="http://www.openarchives.org/OAI/2.0/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/ http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd">
  <responseDate>2026-08-15T16:20:00Z</responseDate>
  <request identifier="23191" metadataPrefix="oai_dc" verb="GetRecord">https://drops.dagstuhl.de/oai</request>
  <GetRecord>
    <record>
      <header>
        <identifier>oai:drops-oai.dagstuhl.de:23191</identifier>
        <datestamp>2025-10-02T12:42:29Z</datestamp>
        <setSpec>ddc:004</setSpec>
        <setSpec>open_access</setSpec>
      </header>
      <metadata>
        <oai_dc:dc xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
          <dc:title>Tiling with Three Polygons Is Undecidable</dc:title>
          <dc:creator>Demaine, Erik D.</dc:creator>
          <dc:creator>Langerman, Stefan</dc:creator>
          <dc:subject>plane tilings</dc:subject>
          <dc:subject>polygons</dc:subject>
          <dc:subject>undecidability</dc:subject>
          <dc:subject>co-RE</dc:subject>
          <dc:description>We prove that the following problem is co-RE-complete and thus undecidable: given three simple polygons, is there a tiling of the plane where every tile is an isometry of one of the three polygons (either allowing or forbidding reflections)? This result improves on the best previous construction which requires five polygons.</dc:description>
          <dc:publisher>Schloss Dagstuhl – Leibniz-Zentrum für Informatik</dc:publisher>
          <dc:contributor>Erik D. Demaine and Stefan Langerman</dc:contributor>
          <dc:date>2025</dc:date>
          <dc:relation>Is Part Of LIPIcs, Volume 332, 41st International Symposium on Computational Geometry (SoCG 2025)</dc:relation>
          <dc:type>InProceedings</dc:type>
          <dc:type>Text</dc:type>
          <dc:type>doc-type:ResearchArticle</dc:type>
          <dc:type>publishedVersion</dc:type>
          <dc:format>application/pdf</dc:format>
          <dc:identifier>doi:10.4230/LIPIcs.SoCG.2025.39</dc:identifier>
          <dc:identifier>urn:nbn:de:0030-drops-231913</dc:identifier>
          <dc:identifier>https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SoCG.2025.39</dc:identifier>
          <dc:language>eng</dc:language>
          <dc:rights>https://creativecommons.org/licenses/by/4.0/legalcode</dc:rights>
        </oai_dc:dc>
      </metadata>
    </record>
  </GetRecord>
</OAI-PMH>
