Results 41 to 50 of about 776 (182)

Enumerative Combinatorics. Volume 2

open access: yes, 2023
Richard Stanley's two-volume basic introduction to enumerative combinatorics has become the standard guide to the topic for students and experts alike.
Stanley, Richard
core  

Intersection Numbers of the Natural Embedding of the Twisted Triality Hexagon T ( q 3 , q ) in PG ( 7 , q 3 )

open access: yesJournal of Combinatorial Designs, Volume 34, Issue 7, Page 306-329, July 2026.
ABSTRACT In this paper, we study and characterise the natural embedding of the twisted triality hexagon T ( q 3 , q ) in PG ( 7 , q 3 ). We begin by describing the possible intersections of subspaces of PG ( 7 , q 3 ) with T ( q 3 , q ). Then, we provide conditions on a set of lines ℒ, which ensure that ℒ forms the line set of a naturally embedded ...
Sebastian Petit, Geertrui Van de Voorde
wiley   +1 more source

Notes on Counting: An Introduction to Enumerative Combinatorics

open access: yes, 2017
Enumerative combinatorics, in its algebraic and analytic forms, is vital to many areas of mathematics, from model theory to statistical mechanics. This book, which stems from many years' experience of teaching, invites students into the subject and ...
Cameron, Peter J., Peter J. Cameron
core   +1 more source

Is It Easier to Count Communities Than Find Them?

open access: yesRandom Structures &Algorithms, Volume 68, Issue 4, July 2026.
ABSTRACT Random graph models with community structure have been studied extensively in the literature. For both the problems of detecting and recovering community structure, an interesting landscape of statistical and computational phase transitions has emerged. A natural unanswered question is: Might it be possible to infer properties of the community
Cynthia Rush   +3 more
wiley   +1 more source

Maximum Induced Trees and Forests of Bounded Degree in Random Graphs

open access: yesRandom Structures &Algorithms, Volume 68, Issue 4, July 2026.
ABSTRACT The asymptotic behavior of the maximum sizes of induced trees and forests has been studied extensively in the last few decades, though the overall picture is far from being complete. In this paper, we close several significant gaps: (1) We prove 2‐point concentration of the maximum sizes of an induced forest and an induced tree with maximum ...
Margarita Akhmejanova   +2 more
wiley   +1 more source

C-Finite Sequences and Riordan Arrays

open access: yesMathematics
Many prominent combinatorial sequences, such as the Fibonacci, Lucas, Pell, Jacobsthal and Tribonacci sequences, are defined by homogeneous linear recurrence relations with constant coefficients.
Donatella Merlini
doaj   +1 more source

On Dedekind's problem, a sparse version of Sperner's theorem, and antichains of a given size in the Boolean lattice

open access: yesJournal of the London Mathematical Society, Volume 114, Issue 1, July 2026.
Abstract Dedekind's problem, dating back to 1897, asks for the total number ψ(n)$\psi (n)$ of antichains contained in the Boolean lattice Bn$B_n$ on n$n$ elements. We study Dedekind's problem using a recently developed method based on the cluster expansion from statistical physics, and as a result, obtain several new results on the number and typical ...
Matthew Jenssen   +2 more
wiley   +1 more source

Two‐Round Ramsey Games on Random Graphs

open access: yesRandom Structures &Algorithms, Volume 68, Issue 3, May 2026.
ABSTRACT Motivated by the investigation of sharpness of thresholds for Ramsey properties in random graphs, Friedgut, Kohayakawa, Rödl, Ruciński and Tetali introduced two variants of a single‐player game whose goal is to colour the edges of a random graph, in an online fashion, so as not to create a monochromatic triangle.
Yahav Alon   +2 more
wiley   +1 more source

Heights of Butterfly Trees

open access: yesRandom Structures &Algorithms, Volume 68, Issue 3, May 2026.
ABSTRACT Binary search trees (BSTs) are fundamental data structures whose performance is largely governed by tree height. We introduce a block model for constructing BSTs by embedding internal BSTs into the nodes of an external BST—a structure motivated by parallel data architectures—corresponding to composite permutations formed via Kronecker or ...
John Peca‐Medlin, Chenyang Zhong
wiley   +1 more source

A categorification of combinatorial Auslander–Reiten quivers

open access: yesJournal of the London Mathematical Society, Volume 113, Issue 5, May 2026.
Abstract We provide a categorification of Oh and Suh's combinatorial Auslander–Reiten quivers in the simply laced case. We work within the perfectly valued derived category pvd(ΠQ)$\mathrm{pvd}(\Pi _Q)$ of the 2‐dimensional Ginzburg dg algebra of a Dynkin quiver Q$Q$.
Ricardo Canesin
wiley   +1 more source

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