44,284 research outputs found
Note on Ward-Horadam H(x) - binomials' recurrences and related interpretations, II
We deliver here second new recurrence formula,
were array is appointed by sequence of
functions which in predominantly considered cases where chosen to be
polynomials . Secondly, we supply a review of selected related combinatorial
interpretations of generalized binomial coefficients. We then propose also a
kind of transfer of interpretation of coefficients onto
coefficients interpretations thus bringing us back to
and Donald Ervin Knuth relevant investigation decades
ago.Comment: 57 pages, 8 figure
Why Delannoy numbers?
This article is not a research paper, but a little note on the history of
combinatorics: We present here a tentative short biography of Henri Delannoy,
and a survey of his most notable works. This answers to the question raised in
the title, as these works are related to lattice paths enumeration, to the
so-called Delannoy numbers, and were the first general way to solve Ballot-like
problems. These numbers appear in probabilistic game theory, alignments of DNA
sequences, tiling problems, temporal representation models, analysis of
algorithms and combinatorial structures.Comment: Presented to the conference "Lattice Paths Combinatorics and Discrete
Distributions" (Athens, June 5-7, 2002) and to appear in the Journal of
Statistical Planning and Inference
Toric Genera
Our primary aim is to develop a theory of equivariant genera for stably
complex manifolds equipped with compatible actions of a torus T^k. In the case
of omnioriented quasitoric manifolds, we present computations that depend only
on their defining combinatorial data; these draw inspiration from analogous
calculations in toric geometry, which seek to express arithmetic, elliptic, and
associated genera of toric varieties in terms only of their fans. Our theory
focuses on the universal toric genus \Phi, which was introduced independently
by Krichever and Loeffler in 1974, albeit from radically different viewpoints.
In fact \Phi is a version of tom Dieck's bundling transformation of 1970,
defined on T^k-equivariant complex cobordism classes and taking values in the
complex cobordism algebra of the classifying space. We proceed by combining the
analytic, the formal group theoretic, and the homotopical approaches to genera,
and refer to the index theoretic approach as a recurring source of insight and
motivation. The resultant flexibility allows us to identify several distinct
genera within our framework, and to introduce parametrised versions that apply
to bundles equipped with a stably complex structure on the tangents along their
fibres. In the presence of isolated fixed points, we obtain universal
localisation formulae, whose applications include the identification of
Krichever's generalised elliptic genus as universal amongst genera that are
rigid on SU-manifolds. We follow the traditions of toric geometry by working
with a variety of illustrative examples wherever possible. For background and
prerequisites we attempt to reconcile the literature of east and west, which
developed independently for several decades after the 1960s.Comment: 35 pages, LaTeX. In v2 references made to the index theoretical
approach to genera; rigidity and multiplicativity results improved;
acknowledgements adde
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