A Garside monoid is a cancellative monoid with a finite lattice generating set; a Garside group is the group of fractions of a Garside monoid. The family of Garside groups contains the Artin-Tits groups of spherical type. We generalise the well-known notion of a parabolic subgroup of an Artin-Tits group into that of a parabolic subgroup of a Garside group. We also define the more general notion...

We define the notion of preGarside group slightly lightening the definition of Garside group so that all Artin-Tits groups are preGarside groups. This paper intends to give a first basic study on these groups. Firstly, we introduce the notion of parabolic subgroup, we prove that any preGarside group has a (partial) complemented presentation, and we characterize the parbolic subgroups in terms o...

This is an expanded version of a series of lectures delivered at the 25th Winter School “Geometry and Physics” in Srni. After a short introduction to Cartan geometries and parabolic geometries, we give a detailed description of the equivalence between parabolic geometries and underlying geometric structures. The second part of the paper is devoted to constructions which relate parabolic geometr...

Let Cg be a smooth projective irreducible curve over C of genus g ≥ 1 and let {p1, p2, . . . , ps} be a set of distinct points on Cg. We fix a nonnegative integer l and denote by Mg(p, λ) the moduli space of parabolic semistable vector bundles of rank r with trivial determinant and fixed parabolic structure of type λ = (λ1, λ2, . . . , λs) at p = (p1, p2, . . . , ps), where each weight λi is in...

In order to extend the blow-up criterion of solutions to the Euler equations, Kozono and Taniuchi [12] have proved a logarithmic Sobolev inequality by means of isotropic (elliptic) BMO norm. In this paper, we show a parabolic version of the Kozono-Taniuchi inequality by means of anisotropic (parabolic) BMO norm. More precisely we give an upper bound for the L∞ norm of a function in terms of its...

The paper suggests a modification of the contracting mapping method for non-linear and non-local parabolic equations. This modification is based on weighted in time energy estimates for the L2-norm of the solution of a parabolic equation via a weighted version of the H−1-norm of the free term such that the inverse matrix of the higher order coefficients of the parabolic equation is included int...

On the rectangular space-time domain G = D (0; T ] with the boundary S = GnG, where D = (0; d), we consider the Dirichlet problem for the singularly perturbed parabolic equation: " 2 @ @x a(x; t) @ @x u(x; t) ! ? c(x; t)u(x; t) ? p(x; t) @ @t u(x; t) = f(x; t); (1a) The perturbation parameter " may take any small positive value, say " 2 (0; 1]. If " = 0, the parabolic equation (1a) degenerates ...

The DeGiorgi-Nash-Moser estimate plays a crucial role in the study of quasilinear elliptic and parabolic equations. In the present paper we shall show that this fundamental estimate holds for solutions of a linear parabolic Volterra inte-grodiierential equation: @u @t = @ @x i a ij (x; t) @u @x j + Z t 0 @ @x i b ij (x; t;) @u @x j dd; where fa ij g and fb ij g are only assumed to be measurable...

The paper is concerned with Lp error analysis of semi-discrete Galerkin FEMs for nonlinear parabolic equations. The classical energy approach relies heavily on the strong regularity assumption of the diffusion coefficient, which may not be satisfied in many physical applications. Here we focus our attention on a general nonlinear parabolic equation (or system) in a convex polygon or polyhedron ...

We analyze the interplay of nonlinearity and dispersion in a dispersion-decreasing photonic bandgap Bragg fiber as a new platform for generating parabolic pulses. A suitably designed linearly tapered, low-index-contrast, solid-core Bragg fiber – amenable to fabrication by conventional modified chemical vapor deposition technology – is shown to yield stable parabolic pulses. The fiber design was...