منابع مشابه
Perturbed Closed Geodesics Are Periodic Orbits: Index and Transversality
We study the classical action functional SV on the free loop space of a closed, finite dimensional Riemannian manifold M and the symplectic action AV on the free loop space of its cotangent bundle. The critical points of both functionals can be identified with the set of perturbed closed geodesics in M . The potential V ∈ C∞(M × S,R) serves as perturbation and we show that both functionals are ...
متن کاملMULTIPLICATION MODULES THAT ARE FINITELY GENERATED
Let $R$ be a commutative ring with identity and $M$ be a unitary $R$-module. An $R$-module $M$ is called a multiplication module if for every submodule $N$ of $M$ there exists an ideal $I$ of $R$ such that $N = IM$. It is shown that over a Noetherian domain $R$ with dim$(R)leq 1$, multiplication modules are precisely cyclic or isomorphic to an invertible ideal of $R$. Moreover, we give a charac...
متن کاملAre traits that experience reinforcement also under sexual selection?
Where closely related species occur in sympatry, reinforcement may result in the evolution of traits involved in species recognition that are at the same time used for within-species mate choice. Drosophila serrata lives in forested habitat on the east coast of Australia, and over the northern half of its distribution it coexists with a closely related species, Drosophila birchii. Here we show ...
متن کاملOn Generalized Cullen and Woodall Numbers That are Also Fibonacci Numbers
The m-th Cullen number Cm is a number of the form m2 m + 1 and the m-th Woodall number Wm has the form m2 m − 1. In 2003, Luca and Stănică proved that the largest Fibonacci number in the Cullen sequence is F4 = 3 and that F1 = F2 = 1 are the largest Fibonacci numbers in the Woodall sequence. A generalization of these sequences is defined by Cm,s = ms m+1 and Wm,s = ms m−1, for s > 1. In this pa...
متن کاملOn second iterated clique graphs that are also third iterated clique graphs
Iterated clique graphs arise when the clique operator is applied to a graph more than once. Determining whether a graph is a clique graph or an iterated clique graph is usually a difficult task. The fact that being a clique graph and being an iterated clique graph are not equivalent things has been proved recently. However, it is still unknown whether the classes of second iterated clique graph...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Bulletin of the American Mathematical Society
سال: 1960
ISSN: 0002-9904
DOI: 10.1090/s0002-9904-1960-10412-0