Search results for "algebra"

Translation as a measure of literary domination: the case of Quebec literature translated in Spain (1975-2004)

2010

Recent literary manifestos claim that “the center is no longer the center” (Le Devoir 2007). Indeed, it is generally admitted that Quebec literature has been more or less independent from the French field since the 1970’s. However, the analysis of the translation of this literature –its international circulation, and the almost compulsory stopover in France before being selected for translation by the agents of other literary fields– reveals various mechanisms through which the French symbolic center still exerts its power. Drawing on the application of Pierre Bourdieu’s sociology of culture to the international space (Casanova 1999; Sapiro 2007, 2008; etc.), this article argues that transl…

An Outline of Morpho-Constructional Analysis

1991

A concept of morpho-constructional analysis is outlined which describes functions of organic features in terms of transformation of energy input into effect output on the strength of physical principles. The dependence of effect outputs on constructional parameters, such as geometrical configurations and material properties, is illustrated in a vector model. It shows that performances of organisms, on principle, can be provided in equivalent manner by different constructional solutions. Options exist in regards to (1) how constructional parameters can be provided by an organism, (2) how particular effects or performances can be produced, and (3) how organizational units can be constrained b…

On the coupling between agent internal and agent/ environmental dynamics: Development of spatial representations in evolving autonomous robots

2008

In this article we describe how a population of evolving robots can autonomously develop forms of spatial representation which allow them to self-localize and to discriminate different locations of their environment by integrating sensory-motor information over time. The evolving robots also display a remarkable ability to generalize their skill in new environmental conditions that they have never experienced before. The analysis of the obtained results indicates that the evolved robots come up with simple and robust solutions that exploit quasi-periodic limit cycle dynamics emerging from the coupling between the robot/environmental dynamics and a robot's internal dynamics. More specifical…

Highly transitive actions of free products

2013

We characterize free products admitting a faithful and highly transitive action. In particular, we show that the group $\PSL_2(\Z)\simeq (\Z/2\Z)*(\Z/3\Z)$ admits a faithful and highly transitive action on a countable set.

Algebraic (2, 2)-transformation groups

2009

This paper contains the more significant part of the article with the same title that will appear in the Volume 12 of Journal of Group Theory (2009). In this paper we determine all algebraic transformation groups $G$, defined over an algebraically closed field $\sf k$, which operate transitively, but not primitively, on a variety $\Omega$, provided the following conditions are fulfilled. We ask that the (non-effective) action of $G$ on the variety of blocks is sharply 2-transitive, as well as the action on a block $\Delta$ of the normalizer $G_\Delta$. Also we require sharp transitivity on pairs $(X,Y)$ of independent points of $\Omega$, i.e. points contained in different blocks.

Tame dynamics and robust transitivity chain-recurrence classes versus homoclinic classes

2014

Partially hyperbolic diffeomorphisms on Heisenberg nilmanifolds and holonomy maps

2014

Abstract In this note we show that all partially hyperbolic automorphisms on a 3-dimensional non-Abelian nilmanifold can be C 1 -approximated by structurally stable C ∞ -diffeomorphisms, whose chain recurrent set consists of one attractor and one repeller. In particular, all these partially hyperbolic automorphisms are not robustly transitive. As a corollary, the holonomy maps of the stable and unstable foliations of the approximating diffeomorphisms are twisted quasiperiodically forced circle homeomorphisms, which are transitive but non-minimal and satisfy certain fiberwise regularity properties.

A generalized transitive closure for relational queries

1988

We augment relational algebra with a generalized transitive closure operator that allows for the efficient evaluation of a subclass of recursive queries. The operator is based on a composition operator which is as general as possible when the operator is required to be associative and when only relational algebra operators are used in its definition. The closure of such a composition can be computed using the well-known efficient algorithms designed for the computation of the usual transitive closure. Besides the case in which complete materialization of recursive relations are required, our strategy also yields an efficient solution in the case in which a selection is applied to the closur…

Towards efficient inductive synthesis: Rapid construction of local regularities

2006

Given several input/output examples of some function we can state the problem: what is the “simplest” function which complies with these examples. This problem is well studied and is known to be very hard in the general case. In this paper we address a special case of the problem, when the target function can be expressed as a simple composition of known functions. We propose a new inductive synthesis algorithm for this case and show that it is efficient enough to synthesize complex geometry formulas.

A relational model for unstructured documents

1987

The logical structure of a document is usually a tree in which the order of the nodes is important at least at some level of the tree. We call a document unstructured if its structure is a single-level ordered tree. The purpose of this paper is to present a many-sorted algebra for handling unstructured documents. The documents in the model are represented by relations. An algebra for handling documents of one type can be extended to an algebra for handling documents of several types. Further, an algebra for handling documents can be extended by the relational algebra for handling documents and relations in a common algebra. The model of this paper can be regarded as a part of a general docu…