Results 51 to 60 of about 11,862 (202)
On the sub-permutations of pattern avoiding permutations
, 2014 There is a deep connection between permutations and trees. Certain sub-structures of permutations, called sub-permutations, bijectively map to sub-trees of binary increasing trees.
Disanto, Filippo, Wiehe, Thomas
core +1 more source
Bidiagonal Decompositions and Accurate Computations for the Ballot Table and the Fibonacci Matrix
Numerical Linear Algebra with Applications, Volume 33, Issue 1, February 2026.ABSTRACT Riordan arrays include many important examples of matrices. Here we consider the ballot table and the Fibonacci matrix. For finite truncations of these Riordan arrays, we obtain bidiagonal decompositions. Using them, algorithms to solve key linear algebra problems for ballot tables and Fibonacci matrices with high relative accuracy are derived.
Jorge Ballarín +2 more
wiley +1 more source
A tropical approach to rigidity: Counting realisations of frameworks
Journal of the London Mathematical Society, Volume 113, Issue 2, February 2026.Abstract A realisation of a graph in the plane as a bar‐joint framework is rigid if there are finitely many other realisations, up to isometries, with the same edge lengths. Each of these finitely many realisations can be seen as a solution to a system of quadratic equations prescribing the distances between pairs of points.
Oliver Clarke +6 more
wiley +1 more source
Zero‐free regions for the independence polynomial on restricted graph classes
Journal of the London Mathematical Society, Volume 113, Issue 2, February 2026.Abstract Generalising the Heilmann–Lieb theorem from statistical physics, Chudnovsky and Seymour [J. Combin. Theory Ser. B, 97 (2007), no. 3, 350–357] showed that the univariate independence polynomial of any claw‐free graph has all of its zeros on the negative real line. In this paper, we show that for any fixed subdivided claw H$H$ and any Δ$\Delta$,
Mark Jerrum, Viresh Patel
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Schubert varieties, linear codes and enumerative combinatorics
Finite Fields and Their Applications, 2005 We consider linear error correcting codes associated to higher dimensional projective varieties defined over a finite field. The problem of determining the basic parameters of such codes often leads to some interesting and difficult questions in combinatorics and algebraic geometry.
GHORPADE, SR, TSFASMAN, MA
openaire +3 more sources
On Multilevel Energy‐Based Fragmentation Methods
International Journal of Quantum Chemistry, Volume 126, Issue 3, January 30, 2026.We investigate the working equations of energy‐based fragmentation methods and present ML‐SUPANOVA, a Möbius‐inversion‐based multilevel fragmentation scheme that enables adaptive, quasi‐optimal truncations to efficiently approximate Born‐Oppenheimer potentials across hierarchies of electronic‐structure methods and basis sets.
James Barker +2 more
wiley +1 more source
A Refined Graph Container Lemma and Applications to the Hard‐Core Model on Bipartite Expanders
Random Structures &Algorithms, Volume 68, Issue 1, January 2026.ABSTRACT We establish a refined version of a graph container lemma due to Galvin and discuss several applications related to the hard‐core model on bipartite expander graphs. Given a graph G$$ G $$ and λ>0$$ \lambda >0 $$, the hard‐core model on G$$ G $$ at activity λ$$ \lambda $$ is the probability distribution μG,λ$$ {\mu}_{G,\lambda } $$ on ...
Matthew Jenssen +2 more
wiley +1 more source
Counting Independent Sets in Percolated Graphs via the Ising Model
Random Structures &Algorithms, Volume 68, Issue 1, January 2026.ABSTRACT Given a graph G$$ G $$, we form a random subgraph Gp$$ {G}_p $$ by including each edge of G$$ G $$ independently with probability p$$ p $$. We provide an asymptotic expansion of the expected number of independent sets in random subgraphs of regular bipartite graphs satisfying certain vertex‐isoperimetric properties, extending the work of ...
Anna Geisler +3 more
wiley +1 more source
A Survey of Alternating Permutations [PDF]
, 2009 This survey of alternating permutations and Euler numbers includes refinements of Euler numbers, other occurrences of Euler numbers, longest alternating subsequences, umbral enumeration of classes of alternating permutations, and the cd-index of the ...
Stanley, Richard P.
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Journal of the London Mathematical Society, Volume 113, Issue 1, January 2026.Abstract In 1935, Philip Hall published what is often referred to as ‘Hall's marriage theorem’ in a short paper (P. Hall, J. Lond. Math. Soc. (1) 10 (1935), no. 1, 26–30.) This paper has been very influential. I state the theorem and outline Hall's proof, together with some equivalent (or stronger) earlier results, and proceed to discuss some the many ...
Peter J. Cameron
wiley +1 more source