Search results for "circle"

Small $C^1$ actions of semidirect products on compact manifolds

2020

Let $T$ be a compact fibered $3$--manifold, presented as a mapping torus of a compact, orientable surface $S$ with monodromy $\psi$, and let $M$ be a compact Riemannian manifold. Our main result is that if the induced action $\psi^*$ on $H^1(S,\mathbb{R})$ has no eigenvalues on the unit circle, then there exists a neighborhood $\mathcal U$ of the trivial action in the space of $C^1$ actions of $\pi_1(T)$ on $M$ such that any action in $\mathcal{U}$ is abelian. We will prove that the same result holds in the generality of an infinite cyclic extension of an arbitrary finitely generated group $H$, provided that the conjugation action of the cyclic group on $H^1(H,\mathbb{R})\neq 0$ has no eige…

On compactness of the difference of composition operators

2004

Abstract Let φ and ψ be analytic self-maps of the unit disc, and denote by C φ and C ψ the induced composition operators. The compactness and weak compactness of the difference T = C φ − C ψ are studied on H p spaces of the unit disc and L p spaces of the unit circle. It is shown that the compactness of T on H p is independent of p ∈[1,∞). The compactness of T on L 1 and M (the space of complex measures) is characterized, and examples of φ and ψ are constructed such that T is compact on H 1 but non-compact on L 1 . Other given results deal with L ∞ , weakly compact counterparts of the previous results, and a conjecture of J.E. Shapiro.

Iterative construction of Dupin cyclides characteristic circles using non-stationary Iterated Function Systems (IFS)

2012

International audience; A Dupin cyclide can be defined, in two different ways, as the envelope of an one-parameter family of oriented spheres. Each family of spheres can be seen as a conic in the space of spheres. In this paper, we propose an algorithm to compute a characteristic circle of a Dupin cyclide from a point and the tangent at this point in the space of spheres. Then, we propose iterative algorithms (in the space of spheres) to compute (in 3D space) some characteristic circles of a Dupin cyclide which blends two particular canal surfaces. As a singular point of a Dupin cyclide is a point at infinity in the space of spheres, we use the massic points defined by J.C. Fiorot. As we su…

Actions de IR et courbure de ricci du Fibré unitaire tangent des surfaces

1986

Characterisation of 2-dimensional Riemannian manifolds (M, g) (in particular, of surfaces with constant gaussian curvatureK=1/c2, o,−1/c2, respectively) whose tangent circle bundle (TcM, gs) (gs=Sasaki metric) admit an «almost-regular» vector field belonging to an eigenspace of the Ricci operator.

Singular levels and topological invariants of Morse Bott integrable systems on surfaces

2016

Abstract We classify up to homeomorphisms closed curves and eights of saddle points on orientable closed surfaces. This classification is applied to Morse Bott foliations and Morse Bott integrable systems allowing us to define a complete invariant. We state also a realization Theorem based in two transformations and one generator (the foliation of the sphere with two centers).

Tangent lines and Lipschitz differentiability spaces

2015

We study the existence of tangent lines, i.e. subsets of the tangent space isometric to the real line, in tangent spaces of metric spaces. We first revisit the almost everywhere metric differentiability of Lipschitz continuous curves. We then show that any blow-up done at a point of metric differentiability and of density one for the domain of the curve gives a tangent line. Metric differentiability enjoys a Borel measurability property and this will permit us to use it in the framework of Lipschitz differentiability spaces. We show that any tangent space of a Lipschitz differentiability space contains at least $n$ distinct tangent lines, obtained as the blow-up of $n$ Lipschitz curves, whe…

Sobolev homeomorphic extensions onto John domains

2020

Abstract Given the planar unit disk as the source and a Jordan domain as the target, we study the problem of extending a given boundary homeomorphism as a Sobolev homeomorphism. For general targets, this Sobolev variant of the classical Jordan-Schoenflies theorem may admit no solution - it is possible to have a boundary homeomorphism which admits a continuous W 1 , 2 -extension but not even a homeomorphic W 1 , 1 -extension. We prove that if the target is assumed to be a John disk, then any boundary homeomorphism from the unit circle admits a Sobolev homeomorphic extension for all exponents p 2 . John disks, being one sided quasidisks, are of fundamental importance in Geometric Function The…

A continuous circle of pseudo-arcs filling up the annulus

1999

We prove an early announcement by Knaster on a decomposition of the plane. Then we establish an announcement by Anderson saying that the plane annulus admits a continlous decomposition into pseudo-arcs such that the quotient space is a simple closed curve. This provides a new plane curve, "a selectible circle of pseudo-aics", and answers some questions of Lewis.

PLANE CURVE DIAGRAMS AND GEOMETRICAL APPLICATIONS

2007

Pircēju rīcību ietekmējošie faktori izvēloties degvielas uzpildes staciju SIA ''Circle K Latvia''.

2021

Bakalaura darba tēma “Pircēju rīcību ietekmējošie faktori, izvēloties degvielas uzpildes staciju SIA “Circle K Latvia”. Bakalaura darba mērķis ir pamatojoties uz pircēju rīcības teorētiskajiem aspektiem, kā arī pētījuma rezultātiem, izanalizēt pircēju rīcību ietekmējošos faktorus, izvēloties degvielas uzpildes staciju SIA “Circle K Latvia”, atklāt nepilnības un izstrādāt priekšlikumus uzņēmuma darbības pilnveidošanai. Bakalaura darbs sastāv no trijām nodaļām. Pirmajā nodaļā ir pētīti teorētiskie aspekti par pircēju rīcību ietekmējošiem faktoriem un lēmuma pieņemšanas procesu. Otrajā nodaļā aprakstīta uzņēmuma darbība un pircēju raksturojums. Trešajā nodaļā tiek analizēti aptaujas anketas re…