--- _id: '433' abstract: - lang: eng text: 'A thrackle is a graph drawn in the plane so that every pair of its edges meet exactly once: either at a common end vertex or in a proper crossing. We prove that any thrackle of n vertices has at most 1.3984n edges. Quasi-thrackles are defined similarly, except that every pair of edges that do not share a vertex are allowed to cross an odd number of times. It is also shown that the maximum number of edges of a quasi-thrackle on n vertices is 3/2(n-1), and that this bound is best possible for infinitely many values of n.' alternative_title: - LNCS author: - first_name: Radoslav full_name: Fulek, Radoslav id: 39F3FFE4-F248-11E8-B48F-1D18A9856A87 last_name: Fulek orcid: 0000-0001-8485-1774 - first_name: János full_name: Pach, János last_name: Pach citation: ama: 'Fulek R, Pach J. Thrackles: An improved upper bound. In: Vol 10692. Springer; 2018:160-166. doi:10.1007/978-3-319-73915-1_14' apa: 'Fulek, R., & Pach, J. (2018). Thrackles: An improved upper bound (Vol. 10692, pp. 160–166). Presented at the GD 2017: Graph Drawing and Network Visualization, Boston, MA, United States: Springer. https://doi.org/10.1007/978-3-319-73915-1_14' chicago: 'Fulek, Radoslav, and János Pach. “Thrackles: An Improved Upper Bound,” 10692:160–66. Springer, 2018. https://doi.org/10.1007/978-3-319-73915-1_14.' ieee: 'R. Fulek and J. Pach, “Thrackles: An improved upper bound,” presented at the GD 2017: Graph Drawing and Network Visualization, Boston, MA, United States, 2018, vol. 10692, pp. 160–166.' ista: 'Fulek R, Pach J. 2018. Thrackles: An improved upper bound. GD 2017: Graph Drawing and Network Visualization, LNCS, vol. 10692, 160–166.' mla: 'Fulek, Radoslav, and János Pach. Thrackles: An Improved Upper Bound. Vol. 10692, Springer, 2018, pp. 160–66, doi:10.1007/978-3-319-73915-1_14.' short: R. Fulek, J. Pach, in:, Springer, 2018, pp. 160–166. conference: end_date: 2017-09-27 location: Boston, MA, United States name: 'GD 2017: Graph Drawing and Network Visualization' start_date: 201-09-25 date_created: 2018-12-11T11:46:27Z date_published: 2018-01-21T00:00:00Z date_updated: 2023-08-24T14:39:32Z day: '21' department: - _id: UlWa doi: 10.1007/978-3-319-73915-1_14 external_id: arxiv: - '1708.08037' intvolume: ' 10692' language: - iso: eng main_file_link: - open_access: '1' url: https://arxiv.org/abs/1708.08037 month: '01' oa: 1 oa_version: Submitted Version page: 160 - 166 publication_status: published publisher: Springer publist_id: '7390' quality_controlled: '1' related_material: record: - id: '5857' relation: later_version status: public scopus_import: 1 status: public title: 'Thrackles: An improved upper bound' type: conference user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 10692 year: '2018' ... --- _id: '9837' abstract: - lang: eng text: Both classical and recent studies suggest that chromosomal inversion polymorphisms are important in adaptation and speciation. However, biases in discovery and reporting of inversions make it difficult to assess their prevalence and biological importance. Here, we use an approach based on linkage disequilibrium among markers genotyped for samples collected across a transect between contrasting habitats to detect chromosomal rearrangements de novo. We report 17 polymorphic rearrangements in a single locality for the coastal marine snail, Littorina saxatilis. Patterns of diversity in the field and of recombination in controlled crosses provide strong evidence that at least the majority of these rearrangements are inversions. Most show clinal changes in frequency between habitats, suggestive of divergent selection, but only one appears to be fixed for different arrangements in the two habitats. Consistent with widespread evidence for balancing selection on inversion polymorphisms, we argue that a combination of heterosis and divergent selection can explain the observed patterns and should be considered in other systems spanning environmental gradients. article_processing_charge: No author: - first_name: Rui full_name: Faria, Rui last_name: Faria - first_name: Pragya full_name: Chaube, Pragya last_name: Chaube - first_name: Hernán E. full_name: Morales, Hernán E. last_name: Morales - first_name: Tomas full_name: Larsson, Tomas last_name: Larsson - first_name: Alan R. full_name: Lemmon, Alan R. last_name: Lemmon - first_name: Emily M. full_name: Lemmon, Emily M. last_name: Lemmon - first_name: Marina full_name: Rafajlović, Marina last_name: Rafajlović - first_name: Marina full_name: Panova, Marina last_name: Panova - first_name: Mark full_name: Ravinet, Mark last_name: Ravinet - first_name: Kerstin full_name: Johannesson, Kerstin last_name: Johannesson - first_name: Anja M full_name: Westram, Anja M id: 3C147470-F248-11E8-B48F-1D18A9856A87 last_name: Westram orcid: 0000-0003-1050-4969 - first_name: Roger K. full_name: Butlin, Roger K. last_name: Butlin citation: ama: 'Faria R, Chaube P, Morales HE, et al. Data from: Multiple chromosomal rearrangements in a hybrid zone between Littorina saxatilis ecotypes. 2018. doi:10.5061/dryad.72cg113' apa: 'Faria, R., Chaube, P., Morales, H. E., Larsson, T., Lemmon, A. R., Lemmon, E. M., … Butlin, R. K. (2018). Data from: Multiple chromosomal rearrangements in a hybrid zone between Littorina saxatilis ecotypes. Dryad. https://doi.org/10.5061/dryad.72cg113' chicago: 'Faria, Rui, Pragya Chaube, Hernán E. Morales, Tomas Larsson, Alan R. Lemmon, Emily M. Lemmon, Marina Rafajlović, et al. “Data from: Multiple Chromosomal Rearrangements in a Hybrid Zone between Littorina Saxatilis Ecotypes.” Dryad, 2018. https://doi.org/10.5061/dryad.72cg113.' ieee: 'R. Faria et al., “Data from: Multiple chromosomal rearrangements in a hybrid zone between Littorina saxatilis ecotypes.” Dryad, 2018.' ista: 'Faria R, Chaube P, Morales HE, Larsson T, Lemmon AR, Lemmon EM, Rafajlović M, Panova M, Ravinet M, Johannesson K, Westram AM, Butlin RK. 2018. Data from: Multiple chromosomal rearrangements in a hybrid zone between Littorina saxatilis ecotypes, Dryad, 10.5061/dryad.72cg113.' mla: 'Faria, Rui, et al. Data from: Multiple Chromosomal Rearrangements in a Hybrid Zone between Littorina Saxatilis Ecotypes. Dryad, 2018, doi:10.5061/dryad.72cg113.' short: R. Faria, P. Chaube, H.E. Morales, T. Larsson, A.R. Lemmon, E.M. Lemmon, M. Rafajlović, M. Panova, M. Ravinet, K. Johannesson, A.M. Westram, R.K. Butlin, (2018). date_created: 2021-08-09T12:46:39Z date_published: 2018-10-09T00:00:00Z date_updated: 2023-08-24T14:50:26Z day: '09' department: - _id: NiBa doi: 10.5061/dryad.72cg113 main_file_link: - open_access: '1' url: https://doi.org/10.5061/dryad.72cg113 month: '10' oa: 1 oa_version: Published Version publisher: Dryad related_material: record: - id: '6095' relation: used_in_publication status: public status: public title: 'Data from: Multiple chromosomal rearrangements in a hybrid zone between Littorina saxatilis ecotypes' type: research_data_reference user_id: 6785fbc1-c503-11eb-8a32-93094b40e1cf year: '2018' ... --- _id: '10864' abstract: - lang: eng text: We prove that every congruence distributive variety has directed Jónsson terms, and every congruence modular variety has directed Gumm terms. The directed terms we construct witness every case of absorption witnessed by the original Jónsson or Gumm terms. This result is equivalent to a pair of claims about absorption for admissible preorders in congruence distributive and congruence modular varieties, respectively. For finite algebras, these absorption theorems have already seen significant applications, but until now, it was not clear if the theorems hold for general algebras as well. Our method also yields a novel proof of a result by P. Lipparini about the existence of a chain of terms (which we call Pixley terms) in varieties that are at the same time congruence distributive and k-permutable for some k. acknowledgement: The second author was supported by National Science Center grant DEC-2011-/01/B/ST6/01006. article_processing_charge: No author: - first_name: Alexandr full_name: Kazda, Alexandr id: 3B32BAA8-F248-11E8-B48F-1D18A9856A87 last_name: Kazda - first_name: Marcin full_name: Kozik, Marcin last_name: Kozik - first_name: Ralph full_name: McKenzie, Ralph last_name: McKenzie - first_name: Matthew full_name: Moore, Matthew last_name: Moore citation: ama: 'Kazda A, Kozik M, McKenzie R, Moore M. Absorption and directed Jónsson terms. In: Czelakowski J, ed. Don Pigozzi on Abstract Algebraic Logic, Universal Algebra, and Computer Science. Vol 16. OCTR. Cham: Springer Nature; 2018:203-220. doi:10.1007/978-3-319-74772-9_7' apa: 'Kazda, A., Kozik, M., McKenzie, R., & Moore, M. (2018). Absorption and directed Jónsson terms. In J. Czelakowski (Ed.), Don Pigozzi on Abstract Algebraic Logic, Universal Algebra, and Computer Science (Vol. 16, pp. 203–220). Cham: Springer Nature. https://doi.org/10.1007/978-3-319-74772-9_7' chicago: 'Kazda, Alexandr, Marcin Kozik, Ralph McKenzie, and Matthew Moore. “Absorption and Directed Jónsson Terms.” In Don Pigozzi on Abstract Algebraic Logic, Universal Algebra, and Computer Science, edited by J Czelakowski, 16:203–20. OCTR. Cham: Springer Nature, 2018. https://doi.org/10.1007/978-3-319-74772-9_7.' ieee: 'A. Kazda, M. Kozik, R. McKenzie, and M. Moore, “Absorption and directed Jónsson terms,” in Don Pigozzi on Abstract Algebraic Logic, Universal Algebra, and Computer Science, vol. 16, J. Czelakowski, Ed. Cham: Springer Nature, 2018, pp. 203–220.' ista: 'Kazda A, Kozik M, McKenzie R, Moore M. 2018.Absorption and directed Jónsson terms. In: Don Pigozzi on Abstract Algebraic Logic, Universal Algebra, and Computer Science. vol. 16, 203–220.' mla: Kazda, Alexandr, et al. “Absorption and Directed Jónsson Terms.” Don Pigozzi on Abstract Algebraic Logic, Universal Algebra, and Computer Science, edited by J Czelakowski, vol. 16, Springer Nature, 2018, pp. 203–20, doi:10.1007/978-3-319-74772-9_7. short: A. Kazda, M. Kozik, R. McKenzie, M. Moore, in:, J. Czelakowski (Ed.), Don Pigozzi on Abstract Algebraic Logic, Universal Algebra, and Computer Science, Springer Nature, Cham, 2018, pp. 203–220. date_created: 2022-03-18T10:30:32Z date_published: 2018-03-21T00:00:00Z date_updated: 2023-09-05T15:37:18Z day: '21' department: - _id: VlKo doi: 10.1007/978-3-319-74772-9_7 editor: - first_name: J full_name: Czelakowski, J last_name: Czelakowski external_id: arxiv: - '1502.01072' intvolume: ' 16' language: - iso: eng main_file_link: - open_access: '1' url: https://arxiv.org/abs/1502.01072 month: '03' oa: 1 oa_version: Preprint page: 203-220 place: Cham publication: Don Pigozzi on Abstract Algebraic Logic, Universal Algebra, and Computer Science publication_identifier: eisbn: - '9783319747729' eissn: - 2211-2766 isbn: - '9783319747712' issn: - 2211-2758 publication_status: published publisher: Springer Nature quality_controlled: '1' scopus_import: '1' series_title: OCTR status: public title: Absorption and directed Jónsson terms type: book_chapter user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1 volume: 16 year: '2018' ... --- _id: '184' abstract: - lang: eng text: We prove that for every d ≥ 2, deciding if a pure, d-dimensional, simplicial complex is shellable is NP-hard, hence NP-complete. This resolves a question raised, e.g., by Danaraj and Klee in 1978. Our reduction also yields that for every d ≥ 2 and k ≥ 0, deciding if a pure, d-dimensional, simplicial complex is k-decomposable is NP-hard. For d ≥ 3, both problems remain NP-hard when restricted to contractible pure d-dimensional complexes. acknowledgement: 'Partially supported by the project EMBEDS II (CZ: 7AMB17FR029, FR: 38087RM) of Czech-French collaboration.' alternative_title: - Leibniz International Proceedings in Information, LIPIcs author: - first_name: Xavier full_name: Goaoc, Xavier last_name: Goaoc - first_name: Pavel full_name: Paták, Pavel last_name: Paták - first_name: Zuzana full_name: Patakova, Zuzana id: 48B57058-F248-11E8-B48F-1D18A9856A87 last_name: Patakova orcid: 0000-0002-3975-1683 - first_name: Martin full_name: Tancer, Martin id: 38AC689C-F248-11E8-B48F-1D18A9856A87 last_name: Tancer orcid: 0000-0002-1191-6714 - first_name: Uli full_name: Wagner, Uli id: 36690CA2-F248-11E8-B48F-1D18A9856A87 last_name: Wagner orcid: 0000-0002-1494-0568 citation: ama: 'Goaoc X, Paták P, Patakova Z, Tancer M, Wagner U. Shellability is NP-complete. In: Vol 99. Schloss Dagstuhl - Leibniz-Zentrum für Informatik; 2018:41:1-41:16. doi:10.4230/LIPIcs.SoCG.2018.41' apa: 'Goaoc, X., Paták, P., Patakova, Z., Tancer, M., & Wagner, U. (2018). Shellability is NP-complete (Vol. 99, p. 41:1-41:16). Presented at the SoCG: Symposium on Computational Geometry, Budapest, Hungary: Schloss Dagstuhl - Leibniz-Zentrum für Informatik. https://doi.org/10.4230/LIPIcs.SoCG.2018.41' chicago: Goaoc, Xavier, Pavel Paták, Zuzana Patakova, Martin Tancer, and Uli Wagner. “Shellability Is NP-Complete,” 99:41:1-41:16. Schloss Dagstuhl - Leibniz-Zentrum für Informatik, 2018. https://doi.org/10.4230/LIPIcs.SoCG.2018.41. ieee: 'X. Goaoc, P. Paták, Z. Patakova, M. Tancer, and U. Wagner, “Shellability is NP-complete,” presented at the SoCG: Symposium on Computational Geometry, Budapest, Hungary, 2018, vol. 99, p. 41:1-41:16.' ista: 'Goaoc X, Paták P, Patakova Z, Tancer M, Wagner U. 2018. Shellability is NP-complete. SoCG: Symposium on Computational Geometry, Leibniz International Proceedings in Information, LIPIcs, vol. 99, 41:1-41:16.' mla: Goaoc, Xavier, et al. Shellability Is NP-Complete. Vol. 99, Schloss Dagstuhl - Leibniz-Zentrum für Informatik, 2018, p. 41:1-41:16, doi:10.4230/LIPIcs.SoCG.2018.41. short: X. Goaoc, P. Paták, Z. Patakova, M. Tancer, U. Wagner, in:, Schloss Dagstuhl - Leibniz-Zentrum für Informatik, 2018, p. 41:1-41:16. conference: end_date: 2018-06-14 location: Budapest, Hungary name: 'SoCG: Symposium on Computational Geometry' start_date: 2018-06-11 date_created: 2018-12-11T11:45:04Z date_published: 2018-06-11T00:00:00Z date_updated: 2023-09-06T11:10:57Z day: '11' ddc: - '516' - '000' department: - _id: UlWa doi: 10.4230/LIPIcs.SoCG.2018.41 file: - access_level: open_access checksum: d12bdd60f04a57307867704b5f930afd content_type: application/pdf creator: dernst date_created: 2018-12-17T16:35:02Z date_updated: 2020-07-14T12:45:18Z file_id: '5725' file_name: 2018_LIPIcs_Goaoc.pdf file_size: 718414 relation: main_file file_date_updated: 2020-07-14T12:45:18Z has_accepted_license: '1' intvolume: ' 99' language: - iso: eng license: https://creativecommons.org/licenses/by/4.0/ month: '06' oa: 1 oa_version: Published Version page: 41:1 - 41:16 publication_status: published publisher: Schloss Dagstuhl - Leibniz-Zentrum für Informatik publist_id: '7736' quality_controlled: '1' related_material: record: - id: '7108' relation: later_version status: public scopus_import: 1 status: public title: Shellability is NP-complete tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: conference user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 99 year: '2018' ... --- _id: '285' abstract: - lang: eng text: In graph theory, as well as in 3-manifold topology, there exist several width-type parameters to describe how "simple" or "thin" a given graph or 3-manifold is. These parameters, such as pathwidth or treewidth for graphs, or the concept of thin position for 3-manifolds, play an important role when studying algorithmic problems; in particular, there is a variety of problems in computational 3-manifold topology - some of them known to be computationally hard in general - that become solvable in polynomial time as soon as the dual graph of the input triangulation has bounded treewidth. In view of these algorithmic results, it is natural to ask whether every 3-manifold admits a triangulation of bounded treewidth. We show that this is not the case, i.e., that there exists an infinite family of closed 3-manifolds not admitting triangulations of bounded pathwidth or treewidth (the latter implies the former, but we present two separate proofs). We derive these results from work of Agol and of Scharlemann and Thompson, by exhibiting explicit connections between the topology of a 3-manifold M on the one hand and width-type parameters of the dual graphs of triangulations of M on the other hand, answering a question that had been raised repeatedly by researchers in computational 3-manifold topology. In particular, we show that if a closed, orientable, irreducible, non-Haken 3-manifold M has a triangulation of treewidth (resp. pathwidth) k then the Heegaard genus of M is at most 48(k+1) (resp. 4(3k+1)). acknowledgement: Research of the second author was supported by the Einstein Foundation (project “Einstein Visiting Fellow Santos”) and by the Simons Foundation (“Simons Visiting Professors” program). alternative_title: - LIPIcs article_number: '46' article_processing_charge: No author: - first_name: Kristóf full_name: Huszár, Kristóf id: 33C26278-F248-11E8-B48F-1D18A9856A87 last_name: Huszár orcid: 0000-0002-5445-5057 - first_name: Jonathan full_name: Spreer, Jonathan last_name: Spreer - first_name: Uli full_name: Wagner, Uli id: 36690CA2-F248-11E8-B48F-1D18A9856A87 last_name: Wagner orcid: 0000-0002-1494-0568 citation: ama: 'Huszár K, Spreer J, Wagner U. On the treewidth of triangulated 3-manifolds. In: Vol 99. Schloss Dagstuhl - Leibniz-Zentrum für Informatik; 2018. doi:10.4230/LIPIcs.SoCG.2018.46' apa: 'Huszár, K., Spreer, J., & Wagner, U. (2018). On the treewidth of triangulated 3-manifolds (Vol. 99). Presented at the SoCG: Symposium on Computational Geometry, Budapest, Hungary: Schloss Dagstuhl - Leibniz-Zentrum für Informatik. https://doi.org/10.4230/LIPIcs.SoCG.2018.46' chicago: Huszár, Kristóf, Jonathan Spreer, and Uli Wagner. “On the Treewidth of Triangulated 3-Manifolds,” Vol. 99. Schloss Dagstuhl - Leibniz-Zentrum für Informatik, 2018. https://doi.org/10.4230/LIPIcs.SoCG.2018.46. ieee: 'K. Huszár, J. Spreer, and U. Wagner, “On the treewidth of triangulated 3-manifolds,” presented at the SoCG: Symposium on Computational Geometry, Budapest, Hungary, 2018, vol. 99.' ista: 'Huszár K, Spreer J, Wagner U. 2018. On the treewidth of triangulated 3-manifolds. SoCG: Symposium on Computational Geometry, LIPIcs, vol. 99, 46.' mla: Huszár, Kristóf, et al. On the Treewidth of Triangulated 3-Manifolds. Vol. 99, 46, Schloss Dagstuhl - Leibniz-Zentrum für Informatik, 2018, doi:10.4230/LIPIcs.SoCG.2018.46. short: K. Huszár, J. Spreer, U. Wagner, in:, Schloss Dagstuhl - Leibniz-Zentrum für Informatik, 2018. conference: end_date: 2018-06-14 location: Budapest, Hungary name: 'SoCG: Symposium on Computational Geometry' start_date: 2018-06-11 date_created: 2018-12-11T11:45:37Z date_published: 2018-06-01T00:00:00Z date_updated: 2023-09-06T11:13:41Z day: '01' ddc: - '516' - '000' department: - _id: UlWa doi: 10.4230/LIPIcs.SoCG.2018.46 external_id: arxiv: - '1712.00434' file: - access_level: open_access checksum: 530d084116778135d5bffaa317479cac content_type: application/pdf creator: dernst date_created: 2018-12-17T15:32:38Z date_updated: 2020-07-14T12:45:51Z file_id: '5713' file_name: 2018_LIPIcs_Huszar.pdf file_size: 642522 relation: main_file file_date_updated: 2020-07-14T12:45:51Z has_accepted_license: '1' intvolume: ' 99' language: - iso: eng month: '06' oa: 1 oa_version: Submitted Version publication_identifier: issn: - '18688969' publication_status: published publisher: Schloss Dagstuhl - Leibniz-Zentrum für Informatik publist_id: '7614' quality_controlled: '1' related_material: record: - id: '7093' relation: later_version status: public scopus_import: 1 status: public title: On the treewidth of triangulated 3-manifolds tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: conference user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 99 year: '2018' ...