Results 61 to 70 of about 2,909 (193)

Generating transformation semigroups using endomorphisms of preorders, graphs, and tolerances [PDF]

open access: yes, 2010
Let ΩΩ be the semigroup of all mappings of a countably infinite set Ω. If U and V are subsemigroups of ΩΩ, then we write U≈V if there exists a finite subset F of ΩΩ such that the subsemigroup generated by U and F equals that generated by V and F.
Morayne, Michal   +11 more
core   +1 more source

Random assignment and shortest path problems [PDF]

open access: yesDiscrete Mathematics & Theoretical Computer Science, 2006
We explore a similarity between the $n$ by $n$ random assignment problem and the random shortest path problem on the complete graph on $n+1$ vertices. This similarity is a consequence of the proof of the Parisi formula for the assignment problem given by
Johan Wästlund
doaj   +1 more source

Tree Independence Number III. Thetas, Prisms and Stars

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT We prove that for every t ∈ N $t\in {\mathbb{N}}$ there exists τ = τ ( t ) ∈ N $\tau =\tau (t)\in {\mathbb{N}}$ such that every (theta, prism, K 1 , t ${K}_{1,t}$)‐free graph has tree independence number at most τ $\tau $ (where we allow “prisms” to have one path of length zero).
Maria Chudnovsky   +2 more
wiley   +1 more source

Combinatorics' A journey to elementary mathematics education [PDF]

open access: yes, 2003
Combinatorics is a part of discrete mathematics. It is a part of modern mathematics that seem to penetrate into the mathematics subject taught in school. Combinatorics forms an inseparable part of the modernization of elementary mathematics education.
Scholtzová, Iveta
core   +1 more source

Extended Rate, more GFUN [PDF]

open access: yesDiscrete Mathematics & Theoretical Computer Science, 2006
We present a software package that guesses formulas for sequences of, for example, rational numbers or rational functions, given the first few terms.
Martin Rubey
doaj   +1 more source

Quasirandomness in discrete mathematics, additive combinatorics and group theory

open access: yes, 2020
The main objective of this bachelor's thesis will be to present the concept of quasirandomness in various mathematical contexts while proving all the pertinent results. We will introduce the results of Fan Chung and Ronald Graham on quasirandom graphs and quasirandom sets, and the results of Timothy Gowers on quasirandom groups.
openaire   +2 more sources

Saturated Partial Embeddings of Planar Graphs

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT In this work, we study how far one can deviate from optimal behavior when embedding a planar graph. For a planar graph G $G$, we say that a plane subgraph H ⊆ G $H\subseteq G$ is a plane‐saturated subgraph if adding any edge (possibly with new vertices) to H $H$ would either violate planarity or make the resulting graph no longer a subgraph of
Alexander Clifton, Nika Salia
wiley   +1 more source

International Journal of Mathematical Combinatorics, Vol.7A [PDF]

open access: yes, 2013
The International J.Mathematical Combinatorics (ISSN 1937-1055) is a fully refereed international journal, sponsored by the MADIS of Chinese Academy of Sciences and published in USA quarterly comprising 460 pages approx.
Mao, Linfan (Editor-in-Chief)
core   +1 more source

The first ascent of size $d$ or more in compositions [PDF]

open access: yesDiscrete Mathematics & Theoretical Computer Science, 2006
A composition of a positive integer $n$ is a finite sequence of positive integers $a_1, a_2, \ldots, a_k$ such that $a_1+a_2+ \cdots +a_k=n$. Let $d$ be a fixed nonnegative integer.
Charlotte Brennan, Arnold Knopfmacher
doaj   +1 more source

Obstructions for Homomorphisms to Odd Cycles in Series‐Parallel Graphs

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT For a graph H $H$, an H $H$‐colouring of a graph G $G$ is a vertex mapping ϕ : V ( G ) → V ( H ) $\phi :V(G)\to V(H)$ such that adjacent vertices are mapped to adjacent vertices. A graph G $G$ is C 2 k + 1 ${C}_{2k+1}$‐critical if G $G$ has no C 2 k + 1 ${C}_{2k+1}$‐colouring but every proper subgraph of G $G$ has a C 2 k + 1 ${C}_{2k+1 ...
Eun‐Kyung Cho   +3 more
wiley   +1 more source

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