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On the edge-colouring problem for unions of complete uniform hypergraphs
1981
Discrete Mathematics
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We now heave -2k+3~1-(k+$n-l:~)sDs -&IL -I-1.) s k -2, and on the other hand D'= C n,(h-2)>--k;l (;)>y&n+2k+3.
The edge-colouring problem for uni&as of complete hypergraphs Lemma 1. ...
(Again we find b + 2c = g f 1 (moo h' and b -t 2c < j12, SO b +2c = g + The edge-co&wing probiem for unions of complete &re.rgmpk~ 12 2k + 1; but by (2j b + c =G k, which is impossible.) ...
doi:10.1016/0012-365x(81)90003-0
fatcat:jhqxurlm6zg5focfmcxogd3cyi
Hypergraph Colouring and Degeneracy
[article]
2014
arXiv
pre-print
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Moreover, the hypergraph is triangle-free, where a "triangle" in an r-uniform hypergraph consists of three edges whose union is a set of r+1 vertices. ...
A hypergraph is "d-degenerate" if every subhypergraph has a vertex of degree at most d. A greedy algorithm colours every such hypergraph with at most d+1 colours. ...
Acknowledgement Thanks to an anonymous referee for pointing out an error in an earlier version of this paper. ...
arXiv:1310.2972v3
fatcat:cl7ylos2a5b7fibfld4eaj2ixm
Ramsey numbers of sparse hypergraphs
2009
Random structures & algorithms (Print)
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Our methods also allow us to prove quite sharp results on the Ramsey number of hypergraphs with at most m edges. r(G) ≤ c(∆)n. ...
We give a short proof that any k-uniform hypergraph H on n vertices with bounded degree ∆ has Ramsey number at most c(∆, k)n, for an appropriate constant c(∆, k). ...
For k-uniform hypergraphs H 1 , . . . , H q , the multicolour Ramsey number r(H 1 , . . . , H q ) is the minimum N such that, in any q-colouring of the edges of the complete k-uniform hypergraph K (k) ...
doi:10.1002/rsa.20260
fatcat:zyafoiymkba7poneyvqvl4zqmy
Ramsey numbers of sparse hypergraphs
[article]
2007
arXiv
pre-print
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Our methods also allows us to prove quite sharp results on the Ramsey number of hypergraphs with at most m edges. ...
We give a short proof that any k-uniform hypergraph H on n vertices with bounded degree Δ has Ramsey number at most c(Δ, k)n, for an appropriate constant c(Δ, k). ...
We would like to thank Jan Hladky for finding several typos in an earlier version of this paper. ...
arXiv:0710.0027v2
fatcat:t6ofknn4hzelxhcdnm3vbirc2e
Hedgehogs are not colour blind
[article]
2015
arXiv
pre-print
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This is the first example of a class of hypergraphs whose Ramsey numbers show a strong dependence on the number of colours. ...
We exhibit a family of 3-uniform hypergraphs with the property that their 2-colour Ramsey numbers grow polynomially in the number of vertices, while their 4-colour Ramsey numbers grow exponentially. ...
One of the main outstanding problems in Ramsey theory is to decide whether the Ramsey number for complete 3-uniform hypergraphs is double exponential. ...
arXiv:1511.00563v1
fatcat:q333shfe4neezdajhevrqmag74
The NP-completeness of finding A-trails in Eulerian graphs and of finding spanning trees in hypergraphs
1995
Discrete Applied Mathematics
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We prove, by a different reduction, that the problem remains NP-complete for simple, 3-connected, plane Eulerian graphs for which all face boundaries are 3-cycles or 4-cycles. ...
We then apply this result to show that it is NP-complete to decide whether a linear hypergraph which is regular of degree 3 has a spanning tree. ...
Acknowledgement The authors wish to thank Carsten Thomassen for his permission to include Theorem 4 and its proof, and to thank Steffen L. Lauritzen for helpful discussions. ...
doi:10.1016/0166-218x(95)80001-k
fatcat:ymtqpxxwvzdolgflhnumveuqx4
Hedgehogs are not colour blind
2017
Journal of Combinatorics
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This is the first example of a class of hypergraphs whose Ramsey numbers show a strong dependence on the number of colours. ...
We exhibit a family of 3-uniform hypergraphs with the property that their 2-colour Ramsey numbers grow polynomially in the number of vertices, while their 4-colour Ramsey numbers grow exponentially. ...
One of the main outstanding problems in Ramsey theory is to decide whether the Ramsey number for complete 3-uniform hypergraphs is double exponential. ...
doi:10.4310/joc.2017.v8.n3.a4
fatcat:p2xzlfxvhvbcdbp2wu5hx2l6yy
Loose Hamilton Cycles in Random 3-Uniform Hypergraphs
[article]
2010
arXiv
pre-print
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In the random hypergraph H=H(n,p;3) each possible triple appears independently with probability p. A loose Hamilton cycle can be described as a sequence of edges x_i,y_i,x_i+1} for i=1,2,...,n/2. ...
Acknowledgement I am grateful to Michael Krivelevich and Oleg Pikhurko for their comments. ...
We say that a k-uniform sub-hypergraph C of H is a Hamilton cycle of type ℓ, for some 1 ≤ ℓ ≤ k, if there exists a cyclic ordering of the vertices V such that every edge consists of k consecutive vertices ...
arXiv:1003.5817v1
fatcat:a7juufprtfh7rlyiranzdlnkcm
Loose Hamilton Cycles in Random 3-Uniform Hypergraphs
2010
Electronic Journal of Combinatorics
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A loose Hamilton cycle can be described as a sequence of edges $\{x_i,y_i,x_{i+1}\}$ for $i=1,2,\ldots,n/2$ where $x_1,x_2,\ldots,x_{n/2},y_1,y_2,\ldots,y_{n/2}$ are all distinct. ...
In the random hypergraph $H=H_{n,p;3}$ each possible triple appears independently with probability $p$. ...
Acknowledgement I am grateful to Andrzej Dudek, Michael Krivelevich, Oleg Pikhurko and Andrzej Ruciński for their comments. ...
doi:10.37236/477
fatcat:cgaeiux4qvbshldktghdwiwzay
Monochromatic paths in 2-edge coloured graphs and hypergraphs
[article]
2022
arXiv
pre-print
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Further, we give a lower bound for the number of tight paths needed to partition any 2-edge-coloured complete k-partite k-uniform hypergraph, and show that any 2-edge coloured bipartite graph has a partition ...
We answer a question of Gyárfás and Sárközy from 2013 by showing that every 2-edge-coloured complete 3-uniform hypergraph can be partitioned into two monochromatic tight paths of different colours. ...
For any n ∈ N, and any colouring of the edges of the 3-uniform complete hypergraph K n , there is a spanning bicolored tight path. ...
arXiv:2204.12464v1
fatcat:wyiy5koju5e45ndvm4qmanl34u
Quasi-Eulerian Hypergraphs
2017
Electronic Journal of Combinatorics
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We provide necessary and sufficient conditions for the existence of an Euler family in an arbitrary hypergraph, and in particular, we show that every 3-uniform hypergraph without cut edges admits an Euler ...
triple systems, as well as recent results by Lonc and Naroski, who showed that the problem of existence of an Euler tour in a hypergraph is NP-complete. ...
Acknowledgements The first author wishes to thank the Department of Mathematics and Statistics, University of Ottawa, for its hospitality during his postdoctoral fellowship, when this research was conducted ...
doi:10.37236/6361
fatcat:4kqzraw3jvbo5ktmm773xwktz4
Page 6438 of Mathematical Reviews Vol. , Issue 95k
[page]
1995
Mathematical Reviews
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For a finite hypergraph H, let P(A) be the number of proper vertex colourings of H in A colours. ...
What is the smallest number of edges in a 3-chromatic 4-uniform hypergraph? ...
Near Perfect Coverings in Graphs and Hypergraphs
1985
European journal of combinatorics (Print)
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Then there exists a collection of (I + 0(1))(2)/(2) induced subgraphs of gil on v vertices, isomorphic to CO and such that each edge (non-edge) of gil is covered by an edge (non-edge) of a graph in the ...
Then there exists a collection of (I + 0(1)) x G)/(~) k-subsets of an n-set so that each r-subset is contained in at least one member of the collection. ...
We denote by ;;(d (n, p) the random d-uniform hypergraph with each edge having probability p for being chosen. Also, K~ denotes the complete d-uniform hypergraph on n vertices. THEOREM 3.1. ...
doi:10.1016/s0195-6698(85)80045-7
fatcat:adqr2ty7qree7px3oefjykddei
Covering numbers for graphs and hypergraphs
[article]
2012
arXiv
pre-print
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2010 pre-print arXiv:1009.5893v1 fatcat:lza3a7y7ivhupnoo5rn6rg3wcq
Consider the edge set E ′ consisting of edges with colour k + 1 or k + 2. Every vertex of H is incident with 1 or 2 edges from E ′ , so E ′ is a union of paths and cycles. ...
Thus f (r, k) is the smallest d such that every d-uniform, r-regular hypergraph has a k-colouring in which every edge has a vertex of every colour. ...
arXiv:1009.5893v2
fatcat:egxo65ohwndujo2rerek4affd4
Graph properties and hypergraph colourings
1991
Discrete Mathematics
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Given a graph property P, graph G and integer k 20, a P k-colouring of G is a function Jr:V(G)+ (1,. . ) k} such that the subgraph induced by each colour class has property P. ...
In particular, we build vertex critical hypergraphs that are not edge critical, construct uniquely colourable hypergraphs with few edges and find graph-to-hypergraph transformations that preserve chromatic ...
The order and size of a hypergraph H are IV(H)1 and [E(H)1 respectively, We remark that Abbott [l] used Ramsey's Theorem on edge colourings of complete hypergraphs to prove the existence of k-chromatic ...
doi:10.1016/0012-365x(91)90034-y
fatcat:33nesuvxsbgshiupw2xrbcx4zi
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