Equivariant Euler–Poincaré characteristic in sheaf cohomology

Let X be a Hausdorff space equipped with a continuous action of a finite group G and a G-stable family of supports \({\Phi}\). Fix a number field F with ring of integers R. We study the class \({\chi = \sum_j (-1)^j [H^j_\Phi (X, \mathcal{E}) \otimes_R F]}\) in the character group of G over F for any flat G-sheaf \({\mathcal{E}}\) of R-modules over X. Under natural cohomological finiteness conditions we give a formula for \({\chi}\) with respect to the basis given by the irreducible characters of G. We discuss applications of our result concerning the cohomology of arithmetic groups.     

Mineyev–Dicks proof of the HN-conjecture and the Euler–Poincaré characteristic

A proof of the Hanna Neumann conjecture (HN-conjecture) based on the ideas of Mineyev andDicks is presented. The new ingredients are theQuillen formula for the Euler–Poincaré characteristic and the “abstract HN-conjecture.”     

Lelong–Poincaré formula in symplectic and almost complex geometry

In this paper, we present two applications of the theory of singular connections developed by Harvey and Lawson (1993). The first one is a version of the Lelong–Poincaré formula with estimates for sections of vector bundles over an almost complex manifold. The second one is a convergence theorem for divisors associated to a general family of symplectic submanifolds constructed by Donaldson (1996) (the case of hypersurfaces) and by Auroux in (1997) (for arbitrary dimensional submanifolds).     

Well-posedness and analytic solutions of the two-component Euler–Poincaré system

We first establish the local well-posedness for the Cauchy problem of the two-component Euler–Poincaré system in nonhomogeneous Besov spaces. Then, we derive a blow-up criterion for strong solutions to the system. Finally, we prove the existence of analytic solutions to the system.     

A Poincaré Cone Condition in the Poincaré Group

Ben Arous and Gradinaru (Potential Anal 8(3):217–258, 1998) described the singularity of the Green function of a general sub-elliptic diffusion. In this article we first adapt their proof to the more general context of a hypoelliptic diffusion. In a second time, we deduce a Wiener criterion and a Poincaré cone condition for a relativistic diffusion with values in the Poincaré group (i.e the group of affine direct isometries of the Minkowski space-time).     

Euler–Goursat-like formula via Laplace–Borel duality

The Goursat formula for the hypergeometric function extends the Euler–Gauss relation to the case of logarithmic singularities.     

Poincaré transformations in nonholonomic mechanics

We report on the application of the Poincaré transformation (from the theory of adaptive geometric integrators) to nonholonomic systems—mechanical systems with non-integrable velocity constraints. We prove that this transformation can be used to express the dynamics of certain nonholonomic systems at a fixed energy value in Hamiltonian form; examples and potential applications are also discussed.     

A Fractional Orlicz–Sobolev Poincaré Inequality in John Domains

Let n ≥ 2, β∈(0, n) and ■ Rnbe a bounded domain. Support that φ : [0, ∞) → [0, ∞)is a Young function which is doubling and satisfies ■If Ω is a John domain, then we show that it supports a(φ~(n/(n-β)), φ)β-Poincaré inequality. Conversely,assume that Ω is simply connected domain when n = 2 or a bounded domain which is quasiconformally equivalent to some uniform domain when n ≥ 3. If Ω supports a((φ~(n/(n-β)), φ)β-Poincaré inequality,then we show that it is a John domain.     

Strong Poincaré recurrence theorem in MV-algebras

The classical Poincaré strong recurrence theorem states that for any probability space (Ω, ℒ, P), any P-measure preserving transformation T, and any A ∈ ℒ, almost all points of A return to A infinitely many times. In the present paper the Poincaré theorem is proved when the σ-algebra ℒ is substituted by an MV-algebra of a special type. Another approach is used in [RIEČAN, B.: Poincaré recurrence theorem in MV-algebras. In: Proc. IFSA-EUSFLAT 2009 (To appear)], where the weak variant of the theorem is proved, of course, for arbitrary MV-algebras. Such generalizations were already done in the literature, e.g. for quantum logic, see [DVUREČENSKIJ, A.: On some properties of transformations of a logic, Math. Slovaca 26 (1976), 131–137.     

Poincaré duality isomorphisms in tensor categories

If for a vector space V of dimension g over a characteristic zero field we denote by ${\wedge }^{i}V$ its alternating powers, and by $V^{\vee }$ its linear dual, then there are natural Poincaré isomorphisms:

${\wedge }^i{V}^{\vee }?{\wedge }^{g?i}V.$

We describe an analogous result for objects in rigid pseudo-abelian $\mathbb{Q}$-linear ACU tensor categories.     

Chebyshev-Type Polynomials Arising in Poincaré Limit Inequalities

Mathematical Notes -     

Best constant in a three-parameter Poincaré inequality

We study the problem of finding the best constant in the generalized Poincaré inequality

A Remark on the Steklov–Poincaré Inequality

Mathematical Notes - In an $$n$$ -dimensional bounded domain $$\Omega_n$$ , $$n\ge 2$$ , we prove the Steklov–Poincaré inequality with the best constant in the case where $$\Omega_n$$ is...     

On a Poincaré type formula for solutions of singular and degenerate elliptic equations

We provide a geometric Poincaré type formula for stable solutions of ?Δ _p (u) = f(u). From this, we derive a symmetry result in the plane. This work is a refinement of previous results obtained by the authors under further integrability and regularity assumptions.