Weyl Group Orbit Functions in Image Processing

Author(s):  
Goce Chadzitaskos ◽  
Lenka Háková ◽  
Ondřej Kajínek
2014 ◽  
Vol 05 (03) ◽  
pp. 501-511 ◽  
Author(s):  
Goce Chadzitaskos ◽  
Lenka Háková ◽  
Ondřej Kajínek

2016 ◽  
Vol 56 (3) ◽  
pp. 202 ◽  
Author(s):  
Lenka Háková ◽  
Jiří Hrivnák ◽  
Lenka Motlochová

The aim of this article is to describe several cubature formulas related to the Weyl group orbit functions, i.e. to the special cases of the Jacobi polynomials associated to root systems. The diagram containing the relations among the special functions associated to the Weyl group orbit functions is presented and the link between the Weyl group orbit functions and the Jacobi polynomials is explicitly derived in full generality. The four cubature rules corresponding to these polynomials are summarized for all simple Lie algebras and their properties simultaneously tested on model functions. The Clenshaw-Curtis method is used to obtain additional formulas connected with the simple Lie algebra <em>C</em><sub>2</sub>.


2016 ◽  
Vol 56 (6) ◽  
pp. 440-447
Author(s):  
Lenka Háková ◽  
Agnieszka Tereszkiewicz

Weyl group orbit functions are defined in the context of Weyl groups of simple Lie algebras. They are multivariable complex functions possessing remarkable properties such as (anti)invariance with respect to the corresponding Weyl group, continuous and discrete orthogonality. A crucial tool in their definition are so-called sign homomorphisms, which coincide with one-dimensional irreducible representations. In this work we generalize the definition of orbit functions using characters of irreducible representations of higher dimensions. We describe their properties and give examples for Weyl groups of rank 2 and 3.


1999 ◽  
Vol 14 (14) ◽  
pp. 937-949 ◽  
Author(s):  
O. HASCHKE ◽  
W. RÜHL

Trigonometric invariants are defined for each Weyl group orbit on the root lattice. They are real and periodic on the co-root lattice. Their polynomial algebra is spanned by a basis which is calculated by means of an algorithm. The invariants of the basis can be used as coordinates in any cell of the co-root space and lead to an exactly solvable model of Sutherland type. We apply this construction to the F4 case.


2013 ◽  
Vol 54 (8) ◽  
pp. 083501 ◽  
Author(s):  
Lenka Háková ◽  
Jiří Hrivnák ◽  
Jiří Patera
Keyword(s):  

Author(s):  
Thomas Krämer

Abstract We show that any Weyl group orbit of weights for the Tannakian group of semisimple holonomic 𝒟 {{\mathscr{D}}} -modules on an abelian variety is realized by a Lagrangian cycle on the cotangent bundle. As applications we discuss a weak solution to the Schottky problem in genus five, an obstruction for the existence of summands of subvarieties on abelian varieties, and a criterion for the simplicity of the arising Lie algebras.


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