Search results for "Dimension"
showing 10 items of 2766 documents
Algebras with intermediate growth of the codimensions
2006
AbstractLet F be a field of characteristic zero and let A be an F-algebra. The polynomial identities satisfied by A can be measured through the asymptotic behavior of the sequence of codimensions and the sequence of colengths of A. For finite dimensional algebras we show that the colength sequence of A is polynomially bounded and the codimension sequence cannot have intermediate growth. We then prove that for general nonassociative algebras intermediate growth of the codimensions is allowed. In fact, for any real number 0<β<1, we construct an algebra A whose sequence of codimensions grows like nnβ.
Asymptotics for Capelli polynomials with involution
2021
Let F be the free associative algebra with involution ∗ over a field F of characteristic zero. We study the asymptotic behavior of the sequence of ∗- codimensions of the T-∗-ideal Γ∗ M+1,L+1 of F generated by the ∗-Capelli polynomials Cap∗ M+1[Y, X] and Cap∗ L+1[Z, X] alternanting on M + 1 symmetric variables and L + 1 skew variables, respectively. It is well known that, if F is an algebraic closed field of characteristic zero, every finite dimensional ∗-simple algebra is isomorphic to one of the following algebras: · (Mk(F ), t) the algebra of k × k matrices with the transpose involution; · (M2m(F ), s) the algebra of 2m × 2m matrices with the symplectic involution; · (Mh(F ) ⊕ Mh(F )op, e…
Healthcare trajectory mining by combining multidimensional component and itemsets
2012
Sequential pattern mining is aimed at extracting correlations among temporal data. Many different methods were proposed to either enumerate sequences of set valued data (i.e., itemsets) or sequences containing multidimensional items. However, in real-world scenarios, data sequences are described as events of both multidimensional items and set valued information. These rich heterogeneous descriptions cannot be exploited by traditional approaches. For example, in healthcare domain, hospitalizations are defined as sequences of multi-dimensional attributes (e.g. Hospital or Diagnosis) associated with two sets, set of medical procedures (e.g. $ \lbrace $ Radiography, Appendectomy $\rbrace$) and…
Does service quality matter in measuring the performance of water utilities?
2008
Abstract Quality is a dimension of water services that has been repeatedly omitted in the study of performance of water utilities. In this paper, Data Envelopment Analysis techniques are used to compute both conventional quantity-based and quality-adjusted scores of technical efficiency for a sample of Spanish water utilities. The key assumptions are that a lack of quality (bad quality) can be regarded as a bad output and the existence of a trade-off between quantity and quality. Our main results indicate that quality matters in measuring technical efficiency, the difference between conventional and quality-adjusted evaluations representing the opportunity cost of maintaining quality. Avera…
Semidirect products of internal groupoids
2010
We give a characterization of those finitely complete categories with initial object and pushouts of split monomorphisms that admit categorical semidirect products. As an application we examine the case of groupoids with fixed set of objects. Further, we extend this to the internal case. (C) 2010 Elsevier B.V. All rights reserved.
Extraction of Endmembers from Spectral Mixtures
1999
Abstract Linear spectral mixture modeling (LSMM) divides each ground resolution element into its constituent materials using endmembers which represent the spectral characteristics of the cover types. However, it is difficult to identify and estimate the spectral signature of pure components or endmembers which form the scene, since they vary with the scale and purpose of the study. We propose three different methods to estimate the spectra of pure components from a set of unknown mixture spectra. Two of the methods consist in different optimization procedures based on objective functions defined from the coordinate axes of the dominant factors. The third one consists in the design of a neu…
A Novel Multidimensional Scaling Technique for Mapping Word-Of-Mouth Discussions
2009
The techniques which utilize Multidimensional Scaling (MDS) as a fundamental statistical tool have been well developed since the late 1970’s. In this paper we show how anMDS scheme can be enhanced by incorporating into it a Stochastic Point Location (SPL) strategy (one which optimizes the former’s gradient descent learning phase) and a new Stress function. The enhanced method, referred to as MDS SPL, has been used in conjunction with a combination of the TF-IDF and Cosine Similarities on a very noisy Word-Of-Mouth (WoM) discussion set consisting of postings concerning mobile phones, yielding extremely satisfying results.
Existence of a traveling wave solution in a free interface problem with fractional order kinetics
2021
Abstract In this paper we consider a system of two reaction-diffusion equations that models diffusional-thermal combustion with stepwise ignition-temperature kinetics and fractional reaction order 0 α 1 . We turn the free interface problem into a scalar free boundary problem coupled with an integral equation. The main intermediary step is to reduce the scalar problem to the study of a non-Lipschitz vector field in dimension 2. The latter is treated by qualitative topological methods based on the Poincare-Bendixson Theorem. The phase portrait is determined and the existence of a stable manifold at the origin is proved. A significant result is that the settling time to reach the origin is fin…
L'etichettatura dei prodotti agroalimentari nella percezione della qualità secondo i consumatori.
2014
Le informazioni sulle certificazioni di qualità o sulla filiera di produzione, confezionamento e vendita sono, per i consumatori, elementi importanti per individuare prodotti ritenuti sicuri. Tali informazioni, se riportate in etichetta, sono determinanti nelle scelte d’acquisto di taluni segmenti di mercato. L’obiettivo di questo studio è conoscere in che misura la rintracciabilità dei prodotti alimentari, rivelata ai consumatori attraverso le etichette, possa essere considerata un elemento rappresentativo della qualità e della sicurezza, anche attraverso l’utilizzo di strumenti innovativi quale il QR code. Sono stati individuati due Capoluoghi italiani, sulla base della suddivisione ISTAT…
Dimensione degli acini e caratteristiche qualitative della cv Syrah
2010
Sono stati studiati nell’ambito della variabilità naturale riscontrata in un vigneto della cv Syrah, gli effetti della dimensione degli acini e dell’esposizione dei grappoli sui componenti dell’acino e sulla qualità dell’uva. Da entrambe le pareti della chioma (est ed ovest) sono stati pesati gli acini di 45 grappoli suddivisi in tre repliche in modo da determinare quattro classi di diverso peso (1. inferiore o uguale a 1,5 g; 2. tra 1,51 e 2,00 g; 3. tra 2,01 e 2,50 g; 4. maggiore di 2,50 g). Il rapporto peso buccia/peso acino non è variato all’aumentare della dimensione degli acini mentre è variato il rapporto peso semi/peso acino. Gli antociani totali sono stati determinati per via spett…