Query-Competitive Sorting with Uncertainty

We study the problem of sorting under incomplete information, when queries are used to resolve uncertainties. Each of n data items has an unknown value, which is known to lie in a given interval. We can pay a query cost to learn the actual value, and we may allow an error threshold in the sorting. The goal is to find a nearly-sorted permutation by performing a minimum-cost set of queries. We show that an offline optimum query set can be found in polynomial time, and that both oblivious and adaptive problems have simple query-competitive algorithms. The query-competitiveness for the oblivious problem is n for uniform query costs, and unbounded for arbitrary costs; for the adaptive problem, the ratio is 2. We then present a unified adaptive strategy for uniform query costs that yields: (i) a 3/2-query-competitive randomized algorithm; (ii) a 5/3-query-competitive deterministic algorithm if the dependency graph has no 2-components after some preprocessing, which has query-competitive ratio 3/2 + O(1/k) if the components obtained have size at least k; (iii) an exact algorithm if the intervals constitute a laminar family. The first two results have matching lower bounds, and we have a lower bound of 7/5 for large components. We also show that the advice complexity of the adaptive problem is floor[n/2] if no error threshold is allowed, and ceil[n/3 * lg 3] for the general case

Learning-Augmented Query Policies for Minimum Spanning Tree with Uncertainty

We study how to utilize (possibly erroneous) predictions in a model for computing under uncertainty in which an algorithm can query unknown data. Our aim is to minimize the number of queries needed to solve the minimum spanning tree problem, a fundamental combinatorial optimization problem that has been central also to the research area of explorable uncertainty. For all integral ? ? 2, we present algorithms that are ?-robust and (1+1/?)-consistent, meaning that they use at most ?OPT queries if the predictions are arbitrarily wrong and at most (1+1/?)OPT queries if the predictions are correct, where OPT is the optimal number of queries for the given instance. Moreover, we show that this trade-off is best possible. Furthermore, we argue that a suitably defined hop distance is a useful measure for the amount of prediction error and design algorithms with performance guarantees that degrade smoothly with the hop distance. We also show that the predictions are PAC-learnable in our model. Our results demonstrate that untrusted predictions can circumvent the known lower bound of 2, without any degradation of the worst-case ratio. To obtain our results, we provide new structural insights for the minimum spanning tree problem that might be useful in the context of query-based algorithms regardless of predictions. In particular, we generalize the concept of witness sets - the key to lower-bounding the optimum - by proposing novel global witness set structures and completely new ways of adaptively using those

Round-competitive algorithms for uncertainty problems with parallel queries

In computing with explorable uncertainty, one considers problems where the values of some input elements are uncertain, typically represented as intervals, but can be obtained using queries. Previous work has considered query minimization in the settings where queries are asked sequentially (adaptive model) or all at once (non-adaptive model). We introduce a new model where k queries can be made in parallel in each round, and the goal is to minimize the number of query rounds. Using competitive analysis, we present upper and lower bounds on the number of query rounds required by any algorithm in comparison with the optimal number of query rounds for the given instance. Given a set of uncertain elements and a family of m subsets of that set, we study the problems of sorting all m subsets and of determining the minimum value (or the minimum element(s)) of each subset. We also study the selection problem, i.e., the problem of determining the i-th smallest value and identifying all elements with that value in a given set of uncertain elements. Our results include 2-round-competitive algorithms for sorting and selection and an algorithm for the minimum value problem that uses at most (2 + ε) · optk + O 1 ε · lg m query rounds for every 0 < ε < 1, where optk is the optimal number of query round

Sorting and Hypergraph Orientation under Uncertainty with Predictions

Learning-augmented algorithms have been attracting increasing interest, but have only recently been considered in the setting of explorable uncertainty where precise values of uncertain input elements can be obtained by a query and the goal is to minimize the number of queries needed to solve a problem. We study learning-augmented algorithms for sorting and hypergraph orientation under uncertainty, assuming access to untrusted predictions for the uncertain values. Our algorithms provide improved performance guarantees for accurate predictions while maintaining worst-case guarantees that are best possible without predictions. For hypergraph orientation, for any $\gamma \geq 2$, we give an algorithm that achieves a competitive ratio of $1+1/\gamma$ for correct predictions and $\gamma$ for arbitrarily wrong predictions. For sorting, we achieve an optimal solution for accurate predictions while still being $2$-competitive for arbitrarily wrong predictions. These tradeoffs are the best possible. We also consider different error metrics and show that the performance of our algorithms degrades smoothly with the prediction error in all the cases where this is possible.Comment: arXiv admin note: text overlap with arXiv:2011.0738

A Complementaridade entre Capacidade de Adaptação e Capacidades Dinâmicas

Objetivo – O objetivo desse estudo é evidenciar que a capacidade de adaptação das organizações depende de capacidades dinâmicas, ou seja, ambas as capacidades são complementares. Metodologia – A abordagem metodológica adotada foi quantitativa. Como coleta de dados, optou-se pela realização de uma pesquisa survey, cuja uma amostra final foi de 172 respondentes de empresas dos Estados Unidos e da Alemanha. Para testar a hipótese central de que “A capacidade de adaptação da empresa depende do desenvolvimento de capacidades dinâmicas”, utilizou-se como técnica de análise a modelagem de equações estruturais, por meio do método PLS e da ferramenta Smart PLS 3.0. Foi realizada também uma análise multigrupo para verificar eventuais diferenças entre os países estudados.Originalidade/Relevância – A relevância desta pesquisa consiste em apontar que a capacidade de adaptação depende das capacidades dinâmicas, e que ambas não devem ser confundidas como sinônimos.Principais resultados – Os resultados permitiram identificar que, tanto para empresas dos Estados Unidos quanto da Alemanha, a capacidade de adaptação se distingue das capacidades dinâmicas, e que as capacidades dinâmicas influenciam na capacidade de adaptação das empresas. Em outras palavras, foi possível constatar que desenvolvimento de capacidades de adaptação de uma organização está associado positivamente ao desenvolvimento de capacidades dinâmicas.Contribuições – Do ponto de vista teórico, este estudo contribuiu para a visão baseada em capacidades, enquanto do ponto de vista gerencial, recomenda-se que os gestores desenvolvam mais as capacidades dinâmicas em suas organizações para uma adaptabilidade mais eficiente e que permita maior competitividade de longo prazo

A PERSPECTIVA DO “NÓS” HEGELIANO NA CRÍTICA DE MARX À ECONOMIA POLÍTICA

The guiding thread of this work will be the common points contained within Hegel's Phenomenology of Spirit, and youth at the maturity of Marx's works. Basically, we will try to address the influence of the Hegelian "We" perspective contained in the Phenomenology of the Spirit in the project of criticism of the presuppositions of the political economy undertaken by Marx, and how the aspect of the socio-historical mediation proposed by Hegel determines the milestones of the Marxian philosophical project.O fio condutor deste trabalho serão os pontos comuns contidos dentro da Fenomenologia do Espírito, de Hegel, e da juventude à maturidade das obras de Marx. Basicamente, procuraremos abordar a influência da perspectiva do “Nós” hegeliano contido na Fenomenologia do Espírito no projeto de crítica aos pressupostos da economia política empreendida por Marx, e como o aspecto da mediação sócio histórica proposta por Hegel determina os marcos do projeto filosófico marxiano.Â

The rediscovery of Pimelodella longipinnis (Borodin, 1927), an enigmatic Atlantic Rainforest catfish species from Southeastern Brazil (Siluriformes: Heptapteridae)

This article is a redescription of Pimelodella longipinnis, an enigmatic catfish previously known only from its holotype and with uncertain type locality. The species is redescribed based on recently collected materials from streams of the Mata Atlântica bioregion, in Santos municipality, São Paulo State, Brazil. Pimelodella longipinnis is assigned to a putatively monophyletic group, the Pimelodella leptosoma-group, diagnosed by the presence of a supraoccipital process not reaching the anterior nuchal plate, with a gap of ca. 20-25% of the supraoccipital process total length, and whose tip notably surpasses the midpoint of the complex vertebra in dorsal view. We also present a list of fish species described from a shipping sent to the American Museum of Natural History from the former Museu Paulista (now Museu de Zoologia da Universidade de São Paulo), of which P. longipinnis was part

Byzantine Failure Detection for Dynamic Distributed Systems

Byzantine failure detectors provide an elegant abstraction for implementing Byzantine fault tolerance. However, as far as we know, there is no general solution for this problem in a dynamic distributed system over wireless networks with unknown membership. This paper presents thus a first Byzantine failure detector for this context. The protocol has the interesting feature to be time-free, that is, it does not rely on timers to detect omission failures. This characteristic favors its scalability and help to deal with the dynamics and unpredictability of those networks.Les détecteurs de défaillances Byzantines offrent une abstraction élégante pour implanter la tolérance aux fautes Byzantines. Cependant, à notre connaissance, il n'existe pas de solution générale pour ce problème dans un système réparti dynamique. Cet article présente un premier détecteur de défaillance Byzantin pour ce type d'environnement. Le protocole proposé est asynchrone dans le sens où les processus n'utilisent pas de temporisateur pour détecter les fautes. Cette caractéristique rend le protocole extensible et adaptable