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A study of the Exponentiated Gradient +/- algorithm for stochastic optimization of neural networks
No full textExponentiated Gradient +/- (abbr. EG+-) is a gradient update algorithmdrawn from work by Manfred Warmuth (Kivinen and Warmuth, 1997) in theonline learning setting. This thesis ports the algorithm into the context of deepneural networks and analyses its fitness in that context compared to the currentstate of the art gradient update methods. Existing methods employ an additiveupdate scheme whereby some fraction of the gradient is added to the weightvalues to update them at each iteration in the gradient descent algorithm. EG+-provides a multiplicative update scheme whereby a proportion of the gradientis multiplied into the original weight value, and then normalized to update theweight. EG+- is motivated by using a relative entropy regularization. This thesisanalyzes various properties and experimental results of the algorithm in comparisonto other update methods, and analyzes EG+- in the context of state of theart residual networks and challenging vision problems. Three published implementationsare experimented with, and demonstrate that EG+- performs betterthan SGD when there are many noisy features, and that it compares well withcommonly used state-of-the art gradient descent optimization methods. EG+-also performs better than most SGD based optimizers on black-box adversarialattacks, with the exception of non momentum based SGD with which it performssimilarly
Manipulating derivation forests by scheduling techniques
No full textAbstractThis paper continues the investigation into k-parallel rewritting begun in (Gonczarowski/Shamir, 1985) and (Gonczarowski/Warmuth, 1985). This rewritting mechanism is a generalization of context-free rewriting; instead of applying a single production (or, alternatively, arbitrarily many productions) at each derivation step, exactly k productions are applied. In the works mentioned above, polynomial dynamic programming algorithms were presented which require constant k and propagating grammars. We solve the various membership problems left open in (Gonczarowski/Warmuth, 1985), for arbitrary grammars, using Scheduling Theory. We develop various kinds of pumping, obtaining bounds on the sizes of k-derivations and k-derivation forests. A polynomial dynamic programming membership algorithm is presented for arbitrary (i.e., possibly nonpropagating) grammars, for fixed k. If k is a variable of the problem, then membership is in NP and, hence, by (Gonczarowski/Warmuth, 1985), NP-complete. For unary alphabets, the latter problem is polynomial. Similarly, membership is polynomial in the size of k if only k is variable
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Religiöse Symbolisierung und kulturelle Codierung von Geschlecht
No full textWinkel H. Religiöse Symbolisierung und kulturelle Codierung von Geschlecht. In: Rendtorff B, Mahs C, Warmuth A-D, eds. Geschlechterverwirrungen. Was wir wissen, was wir glauben und was nicht stimmt. Frankfurt am Main: Campus Verlag; 2020: 39-46
A new riparian Mantidactylus (Brygoomantis) frog from the Tsaratanana and Manongarivo Massifs in northern Madagascar
No full textVences, Miguel, Hildenbrand, Andrea, Warmuth, Katharina M., Andreone, Franco, Glaw, Frank (2018): A new riparian Mantidactylus (Brygoomantis) frog from the Tsaratanana and Manongarivo Massifs in northern Madagascar. Zootaxa 4486 (4): 575-588, DOI: 10.11646/zootaxa.4486.4.1
Batch and on-line parameter estimation of Gaussian mixtures based on the joint entropy
No full textWe describe a new iterative method for parameter estimation of Gaussian mixtures. The new method is based on a framework developed by Kivinen and Warmuth for supervised on-line learning. In contrast to gradient descent and EM, which estimate the mixture’s covariance matrices, the proposed method estimates the inverses of the covariance matrices. Furthermore, the new parameter estimation procedure can be applied in both on-line and batch settings. We show experimentally that it is typically faster than EM, and usually requires about half as many iterations as EM. We also describe experiments with digit recognition that demonstrate the merits of the on-line version
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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