Search results for " complexity."

Upper bound on the communication complexity of private information retrieval

1997

We construct a scheme for private information retrieval with k databases and communication complexity O(n 1/(2k−1) ).

A Neural Network model for the Evaluation of Text Complexity in Italian Language: a Representation Point of View

2018

Abstract The goal of a text simplification system (TS) is to create a new text suited to the characteristics of a reader, with the final goal of making it more understandable.The building of an Automatic Text Simplification System (ATS) cannot be separated from a correct evaluation of the text complexity. In fact the ATS must be capable of understanding if a text should be simplified for the target reader or not. In a previous work we have presented a model capable of classifying Italian sentences based on their complexity level. Our model is a Long Short Term Memory (LSTM) Neural Network capable of learning the features of easy-to-read and complex-to-read sentences autonomously from a anno…

Effect of substrate and seagrass habitat complexity on detritus colonization and decomposition in a Mediterranean coastal lagoon (Thau Lagoon, France…

2019

Living and Not-living Matter: Complexity and Self-Organisation in Kauffman

2016

Which is the relation between the living and not-living matter? In this paper I’ll try to give this question an answer and to explore the underlying framework. I think that the theoretical biologist Stuart Kauffman develops an outstanding and interesting approach, which is formulated within the research field of the non-equilibrium chaotic systems dynamics, the theory of complexity and self-organization and the recent debate on the evolution. Therefore, my aim is to show the way in which Kauffman employs the concept of self-organization to build a not reductionist model that may account for the issues concerning the living and not-living matter by integrating physics with biology. In genera…

Complexity Selection of the Self-Organizing Map

2002

This paper describes how the complexity of the Self-Organizing Map can be selected using the Minimum Message Length principle. The use of the method in textual data analysis is also demonstrated.

Explicit Granger causality in kernel Hilbert spaces

2020

Granger causality (GC) is undoubtedly the most widely used method to infer cause-effect relations from observational time series. Several nonlinear alternatives to GC have been proposed based on kernel methods. We generalize kernel Granger causality by considering the variables cross-relations explicitly in Hilbert spaces. The framework is shown to generalize the linear and kernel GC methods, and comes with tighter bounds of performance based on Rademacher complexity. We successfully evaluate its performance in standard dynamical systems, as well as to identify the arrow of time in coupled R\"ossler systems, and is exploited to disclose the El Ni\~no-Southern Oscillation (ENSO) phenomenon f…

Forbidden Factors and Fragment Assembly

2002

In this paper we approach the fragment assembly problem by using the notion of minimal forbidden factors introduced in previous paper. Denoting by M(w) the set of minimal forbidden factors of a word w, we first focus on the evaluation of the size of elements in M(w) and on designing of an algorithm to recover the word w from M(w). Actually we prove that for a word w randomly generated by a memoryless source with identical symbol probabilities, the maximal length m(w) of words in M(w) is logarithmic and that the reconstruction algorithm runs in linear time. These results have an interesting application to the fragment assembly problem, i.e. reconstruct a word w from a given set I of substrin…

Reducing Local Alphabet Size in Recognizable Picture Languages

2021

A recognizable picture language is defined as the projection of a local picture language defined by a set of two-by-two tiles, i.e. by a strictly-locally-testable (SLT) language of order 2. The family of recognizable picture languages is also defined, using larger k by k tiles, \(k>2\), by the projection of the corresponding SLT language. A basic measure of the descriptive complexity of a picture language is given by the size of the SLT alphabet using two-by-two tiles, more precisely by the so-called alphabetic ratio of sizes: SLT-alphabet/picture-alphabet. We study how the alphabetic ratio changes moving from two to larger tile sizes, and we obtain the following result: any recognizable pi…

An Introduction to Computational Complexity

2016

This chapter is not strictly about algebra. However, this chapter offers a set of mathematical and computational instruments that will allow us to introduce several concepts in the following chapters. Moreover, the contents of this chapter are related to algebra as they are ancillary concepts that help (and in some cases allow) the understanding of algebra.

First assessment of the vermetid reefs along the coasts of Favignana Island (Southern Tyrrhenian Sea)

2015

Intertidal vermetid reefs, particularly vulnerable to environmental changes and human activities, are now experiencing high mortality in several areas of the Mediterranean Sea. Since the increase of knowledge on this habitat is important for conservation purposes, we provide a first baseline assessment of the vermetid reefs along the coasts of the Favignana Island (Marine Protected Area “Egadi Islands”). Preliminary results showed the presence of a true reef, similar to a fringing reef, displaying at least three local patterns, distinguishable for width (from 2.3 to 15.5 m), height of the outer and of the inner margin (from 5.6 to 18 cm and from 8.3 to 26 cm, respectively) and number, width…