Search Results - "Kral, Daniel"
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1
Planar graph with twin-width seven
Published in European journal of combinatorics (01-01-2025)“…We construct a planar graph with twin-width equal to seven…”
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Characterization of matrices with bounded Graver bases and depth parameters and applications to integer programming
Published in Mathematical programming (2024)“…An intensive line of research on fixed parameter tractability of integer programming is focused on exploiting the relation between the sparsity of a constraint…”
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Steinberg's Conjecture is false
Published in Journal of combinatorial theory. Series B (01-01-2017)“…Steinberg conjectured in 1976 that every planar graph with no cycles of length four or five is 3-colorable. We disprove this conjecture…”
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Permutations with fixed pattern densities
Published in Random structures & algorithms (01-01-2020)“…We study scaling limits of random permutations (“permutons”) constrained by having fixed densities of a finite number of patterns. We show that the limit…”
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On the number of pentagons in triangle-free graphs
Published in Journal of combinatorial theory. Series A (01-04-2013)“…Using the formalism of flag algebras, we prove that every triangle-free graph G with n vertices contains at most (n/5)5 cycles of length five. Moreover, the…”
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Three-coloring triangle-free graphs on surfaces VI. 3-colorability of quadrangulations
Published in Journal of combinatorial theory. Series B (01-01-2024)Get full text
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Three-coloring triangle-free graphs on surfaces V. Coloring planar graphs with distant anomalies
Published in Journal of combinatorial theory. Series B (01-09-2021)“…We settle a problem of Havel by showing that there exists an absolute constant d such that if G is a planar graph in which every two distinct triangles are at…”
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Three-coloring triangle-free graphs on surfaces VII. A linear-time algorithm
Published in Journal of combinatorial theory. Series B (01-01-2022)“…We give a linear-time algorithm to decide 3-colorability of a triangle-free graph embedded in a fixed surface, and a quadratic-time algorithm to output a…”
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Three-coloring triangle-free graphs on surfaces IV. Bounding face sizes of 4-critical graphs
Published in Journal of combinatorial theory. Series B (01-09-2021)“…Let G be a 4-critical graph with t triangles, embedded in a surface of genus g. Let c be the number of 4-cycles in G that do not bound a 2-cell face. We prove…”
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Density Maximizers of Layered Permutations
Published in The Electronic journal of combinatorics (09-09-2022)“…A permutation is layered if it contains neither $231$ nor $312$ as a pattern.It is known that, if $\sigma$ is a layered permutation, then the density of…”
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A problem of Erdős and Sós on 3-graphs
Published in Israel journal of mathematics (01-02-2016)“…We show that for every ɛ > 0 there exist δ > 0 and n 0 ∈ ℕ such that every 3-uniform hypergraph on n ≥ n 0 vertices with the property that every k -vertex…”
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Non-Bipartite K-Common Graphs
Published in Combinatorica (Budapest. 1981) (01-02-2022)“…A graph H is k -common if the number of monochromatic copies of H in a k -edge-coloring of K n is asymptotically minimized by a random coloring. For every k ,…”
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Weak regularity and finitely forcible graph limits
Published in Transactions of the American Mathematical Society (01-06-2018)“…Graphons are analytic objects representing limits of convergent sequences of graphs. Lovász and Szegedy conjectured that every finitely forcible graphon, i.e.,…”
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Cycles of a given length in tournaments
Published in Journal of combinatorial theory. Series B (01-01-2023)“…We study the asymptotic behavior of the maximum number of directed cycles of a given length in a tournament: let c(ℓ) be the limit of the ratio of the maximum…”
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15
Quasirandom Latin squares
Published in Random structures & algorithms (01-09-2022)“…We prove a conjecture by Garbe et al. [arXiv:2010.07854] by showing that a Latin square is quasirandom if and only if the density of every 2×3 pattern is…”
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First order convergence of matroids
Published in European journal of combinatorics (01-01-2017)“…The model theory based notion of the first order convergence unifies the notions of the left-convergence for dense structures and the Benjamini–Schramm…”
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Toward characterizing locally common graphs
Published in Random structures & algorithms (01-01-2023)“…A graph H$$ H $$ is common if the number of monochromatic copies of H$$ H $$ in a 2‐edge‐coloring of the complete graph is asymptotically minimized by the…”
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Finitely forcible graphons and permutons
Published in Journal of combinatorial theory. Series B (01-01-2015)“…We investigate when limits of graphs (graphons) and permutations (permutons) are uniquely determined by finitely many densities of their substructures, i.e.,…”
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Maximum edge-cuts in cubic graphs with large girth and in random cubic graphs
Published in Random structures & algorithms (01-12-2012)“…We show that for every cubic graph Gwith sufficiently large girth there exists a probability distribution on edge‐cuts in Gsuch that each edge is in a randomly…”
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Decomposition width of matroids
Published in Discrete Applied Mathematics (01-04-2012)“…Hliněný [P. Hliněný, Branch-width, parse trees, and monadic second-order logic for matroids, J. Combin. Theory Ser. B 96 (2006), 325–351] showed that every…”
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