Search results for "hierarchy"

Kolmogorov numberings and minimal identification

1995

Identification of programs for computable functions from their graphs by algorithmic devices is a well studied problem in learning theory. Freivalds and Chen consider identification of ‘minimal’ and ‘nearly minimal’ programs for functions from their graphs. To address certain problems in minimal identification for Godel numberings, Freivalds later considered minimal identification in Kolmogorov Numberings. Kolmogorov numberings are in some sense optimal numberings and have some nice properties. We prove certain hierarchy results for minimal identification in every Kolmogorov numbering. In addition we also compare minimal identification in Godel numbering versus minimal identification in Kol…

The Monadic Quantifier Alternation Hierarchy over Grids and Graphs

2002

AbstractThe monadic second-order quantifier alternation hierarchy over the class of finite graphs is shown to be strict. The proof is based on automata theoretic ideas and starts from a restricted class of graph-like structures, namely finite two-dimensional grids. Considering grids where the width is a function of the height, we prove that the difference between the levels k+1 and k of the monadic hierarchy is witnessed by a set of grids where this function is (k+1)-fold exponential. We then transfer the hierarchy result to the class of directed (or undirected) graphs, using an encoding technique called strong reduction. It is notable that one can obtain sets of graphs which occur arbitrar…

Probabilities to Accept Languages by Quantum Finite Automata

1999

We construct a hierarchy of regular languages such that the current language in the hierarchy can be accepted by 1-way quantum finite automata with a probability smaller than the corresponding probability for the preceding language in the hierarchy. These probabilities converge to 1/2.

Minimal nontrivial space complexity of probabilistic one- way turing machines

2005

Languages recognizable in o(log log n) space by probabilistic one — way Turing machines are proved to be regular. This solves an open problem in [4].

The monadic quantifier alternation hierarchy over grids and pictures

1998

The subject of this paper is the expressive power of monadic second-order logic over two-dimensional grids. We give a new, self-contained game-theoretical proof of the nonexpressibility results of Matz and Thomas. As we show, this implies the strictness of the monadic second-order quantifier alternation hierarchy over grids.

Potential implementation of reservoir computing models based on magnetic skyrmions

2018

Reservoir Computing is a type of recursive neural network commonly used for recognizing and predicting spatio-temporal events relying on a complex hierarchy of nested feedback loops to generate a memory functionality. The Reservoir Computing paradigm does not require any knowledge of the reservoir topology or node weights for training purposes and can therefore utilize naturally existing networks formed by a wide variety of physical processes. Most efforts prior to this have focused on utilizing memristor techniques to implement recursive neural networks. This paper examines the potential of skyrmion fabrics formed in magnets with broken inversion symmetry that may provide an attractive phy…

The chemistry of competition: exploitation of heterospecific cues depends on the dominance rank in the community

2014

Interspecific competition is an important ecological mechanism shaping the traits of the interacting species and structuring their communities. Less competitive species benefit from evading direct encounters with aggressive dominants, whereas dominant species could use cues left by subordinates to steal their resources or to chase them off. Here, we studied competitive interactions among five common and syntopic ant species in Central Europe (Formica polyctena, Formica rufibarbis, Lasius niger, Myrmica rubra and Tetramorium caespitum) and investigated their ability to react to heterospecific chemical cues. Using aggression assays, we established a clear dominance hierarchy of these species,…

Attacks of songbirds in mixed‐species flocks by Eurasian Sparrowhawks: strategies of predators and potential prey

2020

Black Grouse leks on ice: Female mate sampling by incitation of male competition?

1995

Male-male competition is assumed to limit female choice of mates, but it may also help females to choose the most vigorous males. We studied the mate sampling behaviour of female black grouse (Tetrao tetrix) at spatially unstable leks on ice-covered lakes. In the absence of territories and site-dependence in outcomes of fights, the male dominance hierarchy is very evident on ice. When being courted by dominant males, females frequently tried to approach other males. This was frequently prevented because (1) the courting male and the approached male were involved in physical fight, or (2) the dominant male followed the female and the approached male escaped and avoided contact with him. Thes…

Integrating sustainability into the multi-criteria assessment of urban dietary patterns

2020

AbstractThis study develops a decision-making procedure to help policymakers compare alternative patterns for sustainable diets by reaching a compromise among three criteria: socio-economic perspective, health and environment (including carbon and water footprints). An Analytical Hierarchy Process (AHP) was performed in several stages. First, a total of 25 stakeholders (members of organizations on the Valencia Food Policy Council) evaluated criteria that are relevant to the sustainability of diets. Secondly, a workshop with 14 experts from different backgrounds evaluated by consensus four dietary alternatives: Mediterranean, flexitarian, pescatarian and vegan. In terms of environment, exper…