Results 61 to 70 of about 144,275 (215)
Combinatorics of Positroids [PDF]
Discrete Mathematics & Theoretical Computer Science, 2009 Recently Postnikov gave a combinatorial description of the cells in a totally-nonnegative Grassmannian. These cells correspond to a special class of matroids called positroids.
Suho Oh
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Incidence combinatorics of resolutions
, 2000 We introduce notions of combinatorial blowups, building sets, and nested sets for arbitrary meet-semilattices. This gives a common abstract framework for the incidence combinatorics occurring in the context of De Concini-Procesi models of subspace ...
Dmitry, Eva-maria Feichtner, N. Kozlov
core +4 more sources
Discrete Mathematics, 2006 zbMATH Open Web Interface contents unavailable due to conflicting licenses.
Ryan B. Hayward, Jack van Rijswijck
openaire +1 more source
Colourings of Uniform Group Divisible Designs and Maximum Packings
Journal of Combinatorial Designs, EarlyView.ABSTRACT A weak c $c$‐colouring of a design is an assignment of colours to its points from a set of c $c$ available colours, such that there are no monochromatic blocks. A colouring of a design is block‐equitable, if for each block, the number of points coloured with any available pair of colours differ by at most one.
Andrea C. Burgess +6 more
wiley +1 more source
On Coloring of Fractional Powers of Star, Wheel, Friendship, and Fan Graphs
Indonesian Journal of CombinatoricsLet G be a simple, connected, and undirected graph. For m, n ∈ ℕ, the fractional power Gm/n = (G1/n)m of G is constructed by taking the n-subdivision of G (replacing each edge by a path of length n), and then raising the resulting graph to the m-th power
Farisan Hafizh +4 more
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Extremal skew energy of digraphs with no even cycles [PDF]
Transactions on Combinatorics, 2014 Let $D$ be a digraph with skew-adjacency matrix $S(D)$. Then the skew energy of $D$ is defined to be the sum of the norms of all eigenvalues of $S(D)$. Denote by $mathcal{O}_n$ the class of digraphs on order $n$ with no even cycles, and by $mathcal{O ...
Jing Li, Xueliang Li, Huishu Lian
doaj
Graphs with 3-Rainbow Index n − 1 and n − 2
Discussiones Mathematicae Graph Theory, 2015 Let G = (V (G),E(G)) be a nontrivial connected graph of order n with an edge-coloring c : E(G) → {1, 2, . . . , q}, q ∈ N, where adjacent edges may be colored the same. A tree T in G is a rainbow tree if no two edges of T receive the same color.
Li Xueliang +3 more
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The generalized 3-connectivity of Lexicographic product graphs [PDF]
Discrete Mathematics & Theoretical Computer Science, 2014 Graph ...
Xueliang Li, Yaping Mao
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Transforming Solutions for the Oberwolfach Problem into Solutions for the Spouse‐Loving Variant
Journal of Combinatorial Designs, EarlyView.ABSTRACT The Oberwolfach problem OP ( F ) $\mathrm{OP}(F)$, for a 2‐factor F $F$ of K n ${K}_{n}$, asks whether there exists a 2‐factorization of K n ${K}_{n}$ (if n $n$ is odd) or K n − I ${K}_{n}-I$ (if n $n$ is even) where each 2‐factor is isomorphic to F $F$. Here, I $I$ denotes any 1‐factor of K n ${K}_{n}$. For even n $n$, the problem OP( F ) $(F)
Maruša Lekše, Mateja Šajna
wiley +1 more source
Statistics of Feynman amplitudes in ϕ 4-theory
Journal of High Energy Physics, 2023 The amplitude of subdivergence-free logarithmically divergent Feynman graphs in ϕ 4-theory in 4 spacetime dimensions is given by a single number, the Feynman period. We numerically compute the periods of 1.3 million completed graphs, this represents more
Paul-Hermann Balduf
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