Search results for "REPRESENTATION"
showing 10 items of 1710 documents
La rappresentazione digitale per l’accessibilità al patrimonio culturale
2021
Da diversi anni, la rappresentazione digitale ha assunto un ruolo fondamentale nel campo della valorizzazione del patrimonio culturale, introducendo nuove modalità operative. Allo stesso tempo e con frequenza sempre maggiore siti monumentali, musei e istituzioni culturali si avvalgono di applicazioni e installazioni che, grazie all’impiego di tecnologie di uso comune, adoperano il linguaggio multimediale per consentire l’accessibilità virtuale ai Beni Culturali. Questo contributo racconta brevemente alcuni esempi di approcci e applicazioni pensati per assicurare accessibilità tattile, sonora o virtuale a un’utenza ampia e variegata. Sono qui analizzati approcci differenti che favoriscono il…
Sparse Image Representation by Directionlets
2010
Despite the success of the standard wavelet transform (WT) in image processing in recent years, the efficiency and sparsity of its representation are limited by the spatial symmetry and separability of its basis functions built in the horizontal and vertical directions. One-dimensional discontinuities in images (edges or contours), which are important elements in visual perception, intersect too many wavelet basis functions and lead to a non-sparse representation. To capture efficiently these elongated structures characterized by geometrical regularity along different directions (not only the horizontal and vertical), a more complex multidirectional (M-DIR) and asymmetric transform is requi…
Using discourse segmentation to account for the polyfunctionality of discourse markers:The case of well
2021
Abstract A large number of studies describe the many different functions of polyfunctional discourse markers like well in different contexts and from different theoretical perspectives. In the current paper, we propose to systematize the many different uses identified based on their position with respect to the discourse units they are associated with. Not only can previous findings on well be integrated into a single coherent representation of its uses and functions, but the positions with respect to the discourse units can also be associated with specific functions, thus shedding light on how the polyfunctionality of well is brought about.
Simple and semisimple Lie algebras and codimension growth
1999
Irreducible finitary Lie algebras over fields of positive characteristic
2000
A Lie subalgebra L of [gfr ][lfr ][ ](V) is said to be finitary if it consists of elements of finite rank. We study the situation when L acts irreducibly on the infinite-dimensional vector space V and show: if Char [ ] > 7, then L has a unique minimal ideal I. Moreover I is simple and L/I is solvable.
Rough Set Algebras as Description Domains
2009
Study of the so called knowledge ordering of rough sets was initiated by V.W. Marek and M. Truszczynski at the end of 90-ies. Under this ordering, the rough sets of a fixed approximation space form a domain in which every set ↓ is a Boolean algebra. In the paper, an additional operation inversion on rough set domains is introduced and an abstract axiomatic description of obtained algebras of rough set is given. It is shown that the resulting class of algebras is essentially different from those traditional in rough set theory: it is not definable, for instance, in the class of regular double Stone algebras, and conversely.
On the number of constituents of products of characters
2022
It has been conjectured that if the number of distinct irreducible constituents of the product of two faithful irreducible characters of a finite p-group, for p ≥ 5, is bigger than (p + 1)/2, then it is at least p. We give a counterexample to this conjecture.
Varieties of Codes and Kraft Inequality
2007
Decipherability conditions for codes are investigated by using the approach of Guzman, who introduced in [7] the notion of variety of codes and established a connection between classes of codes and varieties of monoids. The class of Uniquely Decipherable (UD) codes is a special case of variety of codes, corresponding to the variety of all monoids. It is well known that the Kraft inequality is a necessary condition for UD codes, but it is not sufficient, in the sense that there exist codes that are not UD and that satisfy the Kraft inequality. The main result of the present paper states that, given a variety V of codes, if all the elements of V satisfy the Kraft inequality, then V is the var…
Varieties of Codes and Kraft Inequality
2005
Decipherability conditions for codes are investigated by using the approach of Guzman, who introduced in [7] the notion of variety of codes and established a connection between classes of codes and varieties of monoids. The class of Uniquely Decipherable (UD) codes is a special case of variety of codes, corresponding to the variety of all monoids. It is well known that the Kraft inequality is a necessary condition for UD codes, but it is not sufficient, in the sense that there exist codes that are not UD and that satisfy the Kraft inequality. The main result of the present paper states that, given a variety $\mathcal{V}$ of codes, if all the elements of $\mathcal{V}$ satisfy the Kraft inequ…
Invariant characters and coprime actions on finite nilpotent groups
2000
Suppose that a group A acts via automorphisms on a nilpotent group G having coprime order. Given an A-invariant character \(\chi \in {\rm Irr}(G)\), we show that the A-primitive irreducible characters that induce \(\chi \) from an A-invariant subgroup of G all have equal degree. We use this result to obtain some information about the characters of groups of p-length 1.