Results 81 to 90 of about 46,626 (239)

Combinatorics of Explicit Substitutions [PDF]

open access: yesProceedings of the 20th International Symposium on Principles and Practice of Declarative Programming, 2018
$λ\upsilon$ is an extension of the $λ$-calculus which internalises the calculus of substitutions. In the current paper, we investigate the combinatorial properties of $λ\upsilon$ focusing on the quantitative aspects of substitution resolution. We exhibit an unexpected correspondence between the counting sequence for $λ\upsilon$-terms and famous Catalan
Bendkowski, Maciej, Lescanne, Pierre
openaire   +3 more sources

Hodge theory in combinatorics [PDF]

open access: yes, 2017
George Birkhoff proved in 1912 that the number of proper colorings of a finite graph G with n colors is a polynomial in n, called the chromatic polynomial of G.
M. Baker
semanticscholar   +1 more source

Orientations of Graphs With at Most One Directed Path Between Every Pair of Vertices

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT Given a graph G $G$, we say that an orientation D $D$ of G $G$ is a KT orientation if, for all u , v ∈ V ( D ) $u,v\in V(D)$, there is at most one directed path (in any direction) between u $u$ and v $v$. Graphs that admit such orientations have been used to construct graphs with large chromatic number and small clique number that served as ...
Barbora Dohnalová   +3 more
wiley   +1 more source

Combinatorics of Positroids [PDF]

open access: yesDiscrete 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
doaj   +1 more source

On the Hardness of Switching to a Small Number of Edges

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT Seidel's switching is a graph operation which makes a given vertex adjacent to precisely those vertices to which it was non‐adjacent before, while keeping the rest of the graph unchanged. Two graphs are called switching‐equivalent if one can be made isomorphic to the other one by a sequence of switches. Jelínková et al. [DMTCS 13, no. 2, 2011]
Vít Jelínek   +2 more
wiley   +1 more source

A note on global existence for boundary value problems

open access: yesInternational Journal of Mathematics and Mathematical Sciences, 1989
Upper and lower solutions are used in establlsning global existence results for certain two–point boundary value problems for y‴=f(x,y,y′,y″) and y(n)=f(x,y,y′,...,y(n−1)).
Chuan J. Chyan, Johnny Henderson
doaj   +1 more source

Hex and combinatorics

open access: yesDiscrete Mathematics, 2006
zbMATH Open Web Interface contents unavailable due to conflicting licenses.
Ryan B. Hayward, Jack van Rijswijck
openaire   +1 more source

An introduction to Smarandache multi-spaces and mathematical combinatorics [PDF]

open access: yes, 2007
These Smarandache spaces are right theories for objectives by logic. However, the mathematical combinatorics is a combinatorial theory for branches in classical mathematics motivated by a combinatorial speculation.
Linfan Mao, Mao. Linfan
core   +1 more source

Linear Versus Centred Colouring via Pseudogrids

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT A centred colouring of a graph is a vertex colouring in which every connected subgraph contains a vertex whose colour is unique and a linear colouring is a vertex colouring in which every (not‐necessarily induced) path contains a vertex whose colour is unique. For a graph G $G$, the centred chromatic number χ cen ( G ) ${\chi }_{\text{cen}}(G)$
Prosenjit Bose   +4 more
wiley   +1 more source

On Coloring of Fractional Powers of Star, Wheel, Friendship, and Fan Graphs

open access: yesIndonesian Journal of Combinatorics
Let 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
doaj   +1 more source

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