156 research outputs found
Free group representations from vector-valued multiplicative functions, II
No full textLet (Formula presented.) be a non-commutative free group on finitely many generators. In a previous work two of the authors have constructed the class of multiplicative representations of (Formula presented.) and proved them irreducible as representation of (Formula presented.). In this paper we analyze multiplicative representations as representations of (Formula presented.) and we prove a criterium for irreducibility based on the growth of their matrix coefficients
Littlewood–Paley Theory for Triangle Buildings
No full textFor the natural two-parameter filtration (Formula presented.) on the boundary of a triangle building, we define a maximal function and a square function and show their boundedness on (Formula presented.) for (Formula presented.). At the end, we consider (Formula presented.) boundedness of martingale transforms. If the building is of (Formula presented.), then (Formula presented.) can be identified with p-adic Heisenberg group
X-Ray spectra background fitting by projection onto convex sets
No full textAn X-ray spectrum is constituted by a set of peaks superimposed to a background (continuum). If a quantitative estimate of the peak areas is required, then the background must be separated from the spectrum. Several algorithms have been proposed in the literature. These algorithms will generally work well when the amplitudes of the peaks are much more intense than the background. We propose a novel method, based on projections onto convex sets. The algorithm have been tested over a large set of spectra, real and simulated. Some of the results obtained in these tests are reported here and are compared to a widely used continuum estimation method, i.e. the orthogonal polynomial decomposition
- …
