From Hilbert’s 13th problem to essential dimension and back

2021 ◽  
pp. 4-15
Author(s):  
Zinovy Reichstein
Keyword(s):  
2021 ◽  
Vol 224 (2) ◽  
pp. S200-S201
Author(s):  
Eran Bornstein ◽  
Yael Eliner ◽  
Moti Gulersen ◽  
Amos Grunebaum ◽  
Erez Lenchner ◽  
...  

2018 ◽  
Vol 62 (1) ◽  
pp. 291-304
Author(s):  
Dave Benson ◽  
Zinovy Reichstein

AbstractWe examine situations, where representations of a finite-dimensionalF-algebraAdefined over a separable extension fieldK/F, have a unique minimal field of definition. Here the base fieldFis assumed to be a field of dimension ≼1. In particular,Fcould be a finite field ork(t) ork((t)), wherekis algebraically closed. We show that a unique minimal field of definition exists if (a)K/Fis an algebraic extension or (b)Ais of finite representation type. Moreover, in these situations the minimal field of definition is a finite extension ofF. This is not the case ifAis of infinite representation type orFfails to be of dimension ≼1. As a consequence, we compute the essential dimension of the functor of representations of a finite group, generalizing a theorem of Karpenko, Pevtsova and the second author.


2011 ◽  
Vol 118 (2, Part 1) ◽  
pp. 357 ◽  
Author(s):  
Nicholas S. Fogelson ◽  
Stuart Fischbein

2016 ◽  
Vol 28 (6) ◽  
pp. 1072-1100 ◽  
Author(s):  
Kun Zhan ◽  
Jicai Teng ◽  
Jinhui Shi ◽  
Qiaoqiao Li ◽  
Mingying Wang

Inspired by gamma-band oscillations and other neurobiological discoveries, neural networks research shifts the emphasis toward temporal coding, which uses explicit times at which spikes occur as an essential dimension in neural representations. We present a feature-linking model (FLM) that uses the timing of spikes to encode information. The first spiking time of FLM is applied to image enhancement, and the processing mechanisms are consistent with the human visual system. The enhancement algorithm achieves boosting the details while preserving the information of the input image. Experiments are conducted to demonstrate the effectiveness of the proposed method. Results show that the proposed method is effective.


Author(s):  
Indranil Biswas ◽  
Ajneet Dhillon ◽  
Nicole Lemire

AbstractWe find upper bounds on the essential dimension of the moduli stack of parabolic vector bundles over a curve. When there is no parabolic structure, we improve the known upper bound on the essential dimension of the usual moduli stack. Our calculations also give lower bounds on the essential dimension of the semistable locus inside the moduli stack of vector bundles of rank r and degree d without parabolic structure.


Humanities ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 17
Author(s):  
Annabelle Dufourcq

This article investigates the meaning of Merleau-Ponty’s concept of the flesh of the world. This concept brings a cosmological tone to existentialist phenomenology and challenges the grim and gnostic approach that prevails in Heidegger’s and Sartre’s works in particular. Is horror the key mood in ontology as argued by Malabou? This article contends that bright metaphors and magic realism are at least as fundamental, but under one condition: ontology must come to terms with what the author has coined as the “Chandos complex”, namely a form of ambivalence and oscillation between Gnosticism and holism that makes both positions fake and hollow. Dreaming of being one with the world and fantasizing an estrangement from nature work hand in hand and are equally staged. Merleau-Ponty’s philosophy occasionally falls prey to the Chandos complex, which makes his concept of the flesh of the world vulnerable to criticism. This article examines the claim put forward by Renaud Barbaras that “the flesh of the world” is a failed metaphor. It argues that this blissful metaphor is ontologically fundamental as soon as its intrinsic paradoxes are recognized and accepted: the Chandos complex then becomes the key to an ontology that recognizes the imaginary as an essential dimension of being. At stake is an essential link between ontology on the one hand and, on the other hand, metaphors as well as myth-building and narrative-building processes.


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