{"@context":"https:\/\/schema.org\/","@type":"ScholarlyArticle","@id":"#article11060","name":"On the Probe Complexity of Local Computation Algorithms","abstract":"In the Local Computation Algorithms (LCA) model, the algorithm is asked to compute a part of the output by reading as little as possible from the input. For example, an LCA for coloring a graph is given a vertex name (as a \"query\"), and it should output the color assigned to that vertex after inquiring about some part of the graph topology using \"probes\"; all outputs must be consistent with the same coloring. LCAs are useful when the input is huge, and the output as a whole is not needed simultaneously. Most previous work on LCAs was limited to bounded-degree graphs, which seems inevitable because probes are of the form \"what vertex is at the other end of edge i of vertex v?\". In this work we study LCAs for unbounded-degree graphs. In particular, such LCAs are expected to probe the graph a number of times that is significantly smaller than the maximum, average, or even minimum degree. We show that there are problems that have very efficient LCAs on any graph - specifically, we show that there is an LCA for the weak coloring problem (where a coloring is legal if every vertex has a neighbor with a different color) that uses log^* n+O(1) probes to reply to any query. As another way of dealing with large degrees, we propose a more powerful type of probe which we call a strong probe: given a vertex name, it returns a list of its neighbors. Lower bounds for strong probes are stronger than ones in the edge probe model (which we call weak probes). Our main result in this model is that roughly Omega(sqrt{n}) strong probes are required to compute a maximal matching.\nOur findings include interesting separations between closely related problems. For weak probes, we show that while weak 3-coloring can be done with probe complexity log^* n+O(1), weak 2-coloring has probe complexity Omega(log n\/log log n). For strong probes, our negative result for maximal matching is complemented by an LCA for (1-epsilon)-approximate maximum matching on regular graphs that uses O(1) strong probes, for any constant epsilon>0.","keywords":["Local computation algorithms","sublinear algorithms"],"author":[{"@type":"Person","name":"Feige, Uriel","givenName":"Uriel","familyName":"Feige","affiliation":"Weizmann Institute of Science, Rehovot, Israel","funding":"Supported in part by the Israel Science Foundation (grant No. 1388\/16). Work partly done in Microsoft Research, Herzeliya, Israel."},{"@type":"Person","name":"Patt-Shamir, Boaz","givenName":"Boaz","familyName":"Patt-Shamir","affiliation":"Tel Aviv University, Tel Aviv, Israel","funding":"Supported in part by the Israel Science Foundation (grant No. 1444\/14)."},{"@type":"Person","name":"Vardi, Shai","givenName":"Shai","familyName":"Vardi","affiliation":"California Institute of Technology, Pasadena, CA, USA","funding":"Supported in part by the I-CORE in Algorithms Postdoctoral Fellowship, the Linde Foundation and NSF grants CNS-1254169 and CNS-1518941. Part of the research was carried out when Shai was a postdoctoral researcher at the Weizmann Institute of Science."}],"position":50,"pageStart":"50:1","pageEnd":"50:14","dateCreated":"2018-07-04","datePublished":"2018-07-04","isAccessibleForFree":true,"license":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/legalcode","copyrightHolder":[{"@type":"Person","name":"Feige, Uriel","givenName":"Uriel","familyName":"Feige","affiliation":"Weizmann Institute of Science, Rehovot, Israel","funding":"Supported in part by the Israel Science Foundation (grant No. 1388\/16). Work partly done in Microsoft Research, Herzeliya, Israel."},{"@type":"Person","name":"Patt-Shamir, Boaz","givenName":"Boaz","familyName":"Patt-Shamir","affiliation":"Tel Aviv University, Tel Aviv, Israel","funding":"Supported in part by the Israel Science Foundation (grant No. 1444\/14)."},{"@type":"Person","name":"Vardi, Shai","givenName":"Shai","familyName":"Vardi","affiliation":"California Institute of Technology, Pasadena, CA, USA","funding":"Supported in part by the I-CORE in Algorithms Postdoctoral Fellowship, the Linde Foundation and NSF grants CNS-1254169 and CNS-1518941. Part of the research was carried out when Shai was a postdoctoral researcher at the Weizmann Institute of Science."}],"copyrightYear":"2018","accessMode":"textual","accessModeSufficient":"textual","creativeWorkStatus":"Published","inLanguage":"en-US","sameAs":"https:\/\/doi.org\/10.4230\/LIPIcs.ICALP.2018.50","publisher":"Schloss Dagstuhl \u2013 Leibniz-Zentrum f\u00fcr Informatik","citation":["http:\/\/arxiv.org\/abs\/1402.3796","http:\/\/arxiv.org\/abs\/1703.07734","http:\/\/dx.doi.org\/10.1017\/S0963548309990186","http:\/\/dx.doi.org\/10.1145\/2956584","http:\/\/users.cms.caltech.edu\/~plondon\/loco.pdf"],"isPartOf":{"@type":"PublicationVolume","@id":"#volume6310","volumeNumber":107,"name":"45th International Colloquium on Automata, Languages, and Programming (ICALP 2018)","dateCreated":"2018-07-04","datePublished":"2018-07-04","editor":[{"@type":"Person","name":"Chatzigiannakis, Ioannis","givenName":"Ioannis","familyName":"Chatzigiannakis"},{"@type":"Person","name":"Kaklamanis, Christos","givenName":"Christos","familyName":"Kaklamanis"},{"@type":"Person","name":"Marx, D\u00e1niel","givenName":"D\u00e1niel","familyName":"Marx"},{"@type":"Person","name":"Sannella, Donald","givenName":"Donald","familyName":"Sannella"}],"isAccessibleForFree":true,"publisher":"Schloss Dagstuhl \u2013 Leibniz-Zentrum f\u00fcr Informatik","hasPart":"#article11060","isPartOf":{"@type":"Periodical","@id":"#series116","name":"Leibniz International Proceedings in Informatics","issn":"1868-8969","isAccessibleForFree":true,"publisher":"Schloss Dagstuhl \u2013 Leibniz-Zentrum f\u00fcr Informatik","hasPart":"#volume6310"}}}