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Perspesctivas da complexidade aplicadas à gestão de empresas.; Perspectives of complexity applied to management.

Borgatti Neto, Ricardo
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 28/03/2008 PT
Relevância na Pesquisa
36.41%
O presente trabalho explora como duas abordagens gerais da complexidade - ciências da complexidade e pensamento complexo - estão influenciando e podem vir a influenciar a gestão de sistemas organizacionais produtivos. Constata-se um aumento de publicações que relacionam a Complexidade à Gestão. Por meio de análise de conteúdo de trabalhos acadêmicos internacionais e nacionais identifica-se uma diminuição na ênfase inicial sobre teoria do caos e fractais e uma tendência recente na exploração da dinâmica de redes, ao mesmo tempo em que modelos baseados em agentes são cada vez mais explorados (associados à idéia de sistemas adaptativos complexos - SAC). Na produção nacional nota-se também a presença de idéias de cunho mais filosófico relacionadas à complexidade, notoriamente as do pensamento complexo do francês Edgar Morin. Com base na história do pensamento científico são identificados fundamentos do paradigma mecanicista dominante e fatores que estão contribuindo para transição de fase desse paradigma, relacionados ao aumento de complexidade na ciência e ao surgimento das ciências da complexidade. Estas ciências são caracterizadas como um processo evolutivo da Teoria Geral de Sistemas e possuem uma diversidade de contribuições em evolução...

Utilização das horas de enfermagem em salas de operações, segundo a complexidade do paciente e do procedimento anestésico-cirúrgico; The utilization of nursing hours in operating rooms, according to the patient's complexity and the surgical anesthetic procedure

Mattia, Ana Lucia De
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 04/12/2002 PT
Relevância na Pesquisa
36.45%
Esta pesquisa é um estudo de caso, com natureza exploratória, descritiva e comparativa de campo, transversal e com abordagem quantitativa. Tem como objetivo classificar as cirurgias em categorias, segundo a necessidade de horas de enfermagem em salas de operações, subsidiando o dimensionamento de pessoal de enfermagem em centro cirúrgico. Foi realizada em um Hospital geral, de grande porte, da rede privada da cidade de São Paulo. A amostra foi constituída de 140 pacientes, divididos em 14 grupos, sendo 10 pacientes em cada grupo. Para a formação dos grupos foi considerado a condição física do paciente, segundo Americam Society of Anestesiologists (ASA), o porte anestésico segundo a Associação Médica Brasileira (AMB), o tipo de procedimento anestésico-cirúrgico, invasivo ou minimamente invasivo (MI) e cirurgias eletivas. Quanto à condição física do paciente, os grupos foram formados com ASA1, ASA2 e ASA3; a ASA4 foi excluída por não apresentar casos, ASA 5 e 6 foram excluídos por serem cirurgias de urgência ou emergência. Quanto ao porte anestésico, as cirurgias foram classificadas em pequeno porte, médio porte, grande porte e porte especial. Desta forma os grupos ficaram simbolizados como: 1P, 1M, 1G, 1E...

Análise formal da complexidade de algoritmos genéticos; Formal analysis of genetic algorithms complexity

Aguiar, Marilton Sanchotene de
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
36.4%
O objetivo do trabalho é estudar a viabilidade de tratar problemas de otimização, considerados intratáveis, através de Algoritmos Genéticos, desenvolvendo critérios para a avaliação qualitativa de um Algoritmo Genético. Dentro deste tema, abordam-se estudos sobre complexidade, classes de problemas, análise e desenvolvimento de algoritmos e Algoritmos Genéticos, este ultimo sendo objeto central do estudo. Como produto do estudo deste tema, é proposto um método de desenvolvimento de Algoritmos Genéticos, utilizando todo o estudo formal de tipos de problemas, desenvolvimento de algoritmos aproximativos e análise da complexidade. O fato de um problema ser teoricamente resolvível por um computador não é suficiente para o problema ser na prática resolvível. Um problema é denominado tratável se no pior caso possui um algoritmo razoavelmente eficiente. E um algoritmo é dito razoavelmente eficiente quando existe um polinômio p tal que para qualquer entrada de tamanho n o algoritmo termina com no máximo p(n) passos [SZW 84]. Já que um polinômio pode ser de ordem bem alta, então um algoritmo de complexidade polinomial pode ser muito ineficiente. Genéticos é que se pode encontrar soluções aproximadas de problemas de grande complexidade computacional mediante um processo de evolução simulada[LAG 96]. Como produto do estudo deste tema...

The effects of habitat complexity and hydraulic conditions on the establishment of benthic stream macroalgae

Tonetto, Aurelio Fajar; Cardoso-Leite, Ricardo; Peres, Cleto K.; Bispo, Pitagoras da Conceição; Branco, Ciro Cesar Zanini
Fonte: Wiley-Blackwell Publicador: Wiley-Blackwell
Tipo: Artigo de Revista Científica Formato: 1687-1694
ENG
Relevância na Pesquisa
36.43%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Processo FAPESP: 07/52608-1; Processo FAPESP: 12/21196-8; Processo FAPESP: 10/17563-0; 1. Habitat complexity is thought to play an important role in various ecological communities, but its role under variable natural conditions is not well understood, particularly in lotic habitats where the complexity of the substratum influences the diversity and abundance of the benthic community.2. We investigated the effects of the habitat complexity of the substratum, as represented by fractal structure, on the establishment of stream macroalgae. We also analysed the influence of hydraulic conditions associated with variations in the fractal dimension of the substratum. We hypothesised that habitats with higher surface complexity would have higher macroalgal abundance and that hydraulic conditions would affect macroalgal establishment differently on surfaces of differing complexity.3. We designed a field experiment to elucidate the role of habitat complexity (represented by the fractal dimension and density of roughness elements) and consequent hydraulic conditions (assessed by the Reynolds number and drag forces) on algal growth. Sterile artificial substrata with five levels of complexity were placed in four unshaded streams. After 60 days of complete submergence...

Advice for Semifeasible Sets and the Complexity-Theoretic Cost(lessness) of Algebraic Properties

Hemaspaandra, Lane A.
Fonte: University of Rochester. Computer Science Department. Publicador: University of Rochester. Computer Science Department.
Tipo: Relatório
ENG
Relevância na Pesquisa
36.42%
This paper provides a tutorial overview of the advice complexity of the semifeasible sets---informally put, the class of sets having a polynomial-time algorithm that, given as input any two strings of which at least one belongs to the set, will choose one that does belong to the set. No previous familiarity with either the semifeasible sets or advice complexity will assumed, and when we include proofs we will try to make the material as accessible as possible via providing intuitive, informal presentations. Karp and Lipton (1980) introduced advice complexity about a quarter of a century ago. Advice complexity asks, for a given power of interpreter, how many bits of ``help' suffice to accept a given set. Thus, this is a notion that contains aspects both of informational complexity and of computational complexity. We will see that for some powers of interpreter the (worst-case) complexity of the semifeasible sets is known right down to the bit (and beyond), but that for the most central power of interpreter---deterministic polynomial time---the complexity is currently known only to be at least linear and at most quadratic. While overviewing the advice complexity of the semifeasible sets, we will stress also the issue of whether the functions at the core of semifeasibility---so-called selector functions---can without cost be chosen to possess such algebraic properties as commutativity and associativity. We will see that this is relevant...

Communication Complexity

Hauser, George J.
Fonte: University of Rochester. Computer Science Department. Publicador: University of Rochester. Computer Science Department.
Tipo: Relatório
ENG
Relevância na Pesquisa
36.4%
Ph.D. Thesis, Computer Science Dept., U. Rochester, Gary L. Peterson, thesis advisor; simultaneously published in the Technical Reprt series; A complete and formal model of computation for a network of two communicating processes is presented which uses an extension of the Turing Machine called a Communicating Turing Machine (CTM). The resources of number of symbols exchanged and maximum amount of local storage used between messages are identified and referred to as the communication time and communication space respectively. As a pair of processors, each with its own input, a fortiori accepts a set of pairs of strings, some consideration must be given to the mapping of problems to CTM inputs. A model parameter is this input mapping function. In addition to consideration of the usual partition mapping, we introduce a distribution mapping which bounds only the number of fragments into which an input is divided, and all partitions with this fragmentation are allowed. Complexity classes for each input mapping function are identified. A full, dense hierarchy is shown to exist in communication space and time from constant up to linear. For distribution input mappings, it is shown that the constant complexity classes are exactly the regular languages and that there is a gap between constant and log log n in the space hierarchy. For fair partition input mappings most of the structure of standard TM complexity obtains for Communication Complexity. An upper bound is given for the communication space complexity of Context Free languages and it is shown that the bound is met for bounded-fragmentation partitions. Example languages demonstrate that most complexity class relationships under fair partitions cannot be improved. An algorithm is presented that optimizes the communication time complexity of an existing communication protocol for a finite language. A new lower bound for communication complexity is presented which uses the number of equivalence classes of strings induced by the language and the input mapping function independently. It is shown that this lower bound is within a constant factor of the required minimum for communication time on fixed-cut partition input mappings.

Using Randomness to Characterize the Complexity of Computation

Hemachandra, Lane A. ; Wechsung, Gerd
Fonte: University of Rochester. Computer Science Department. Publicador: University of Rochester. Computer Science Department.
Tipo: Relatório
ENG
Relevância na Pesquisa
36.41%
extends Cornell Computer Science Dept. TR86-795; Kolmogorov complexity-the study of the randomness of strings-has developed into a fundamental tool in proving lower bounds in computation and in constructing oracles separating complexity classes. In this paper, we show that Kolmogorov complexity is a central tool in the understanding of deterministic and nondeterministic complexity classes and hierarchies; we show that many collapses of computational complexity classes can be completely characterized in terms of Kolmogorov complexity. We discuss P, NP, unique polynomial time, the polynomial hierarchy, and the exponential hierarchy. We show that, for many complexity classes C, C equals a smaller complexity class unless some language in C is accepted only by machines whose execution creates computational structures with a non-trivial degree of randomness. Our fundamental proof technique is a divide and conquer scheme on the tree of potential computational structures.

Economic complexity, regime transition and sectoral forces: the impact of trade unions on democratization in Zimbabwe, South Africa and Zambia

McCorley, Ciara
Fonte: University of Limerick Publicador: University of Limerick
Tipo: info:eu-repo/semantics/doctoralThesis; all_ul_research; ul_published_reviewed; ul_theses_dissertations
ENG
Relevância na Pesquisa
36.44%
peer-reviewed; This thesis interrogates uncertainty in transitional politics in South Africa, Zambia, and Zimbabwe. It questions why some countries transition to democracy and some stagnate or revert to authoritarianism. To address the dual nature of political contingency and structural formations in transitional politics, it adopts a conceptual framework based on economic complexity, to ascertain the relationship between economic structures and the results of regime transition. This study engages with the extensive literature linking economic development and democracy throughout the world, to see if it can be applied to the recent and on-going transitional events across Africa. It identified trade union confederations as economically important actors whose political contingency was directly affected by the sectoral composition of each country’s economy. In other world regions, trade unions have been of import in determining transitional outcomes, and this thesis interrogated whether the same was true in three African countries. The concept of economic complexity was developed to offer a conceptual framework through which to understand transitional politics. It was argued that the more complex the economy, the more likely democracy was to emerge following transition because there would be more factors in play in the political-economic arena that could erode a regime’s relative power and thus bestow power onto other actors who could utilize it for regime change. In terms of indicators...

Information Complexity Density and Simulation of Protocols

Tyagi, Himanshu; Venkatakrishnan, Shaileshh; Viswanath, Pramod; Watanabe, Shun
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.44%
A simulation of an interactive protocol entails the use of interactive communication to produce the output of the protocol to within a fixed statistical distance $\epsilon$. Recent works have proposed that the information complexity of the protocol plays a central role in characterizing the minimum number of bits that the parties must exchange for a successful simulation, namely the distributional communication complexity of simulating the protocol. Several simulation protocols have been proposed with communication complexity depending on the information complexity of the simulated protocol. However, in the absence of any general lower bounds for distributional communication complexity, the conjectured central role of information complexity is far from settled. We fill this gap and show that the distributional communication complexity of $\epsilon$-simulating a protocol is bounded below by the $\epsilon$-tail $\lambda_\epsilon$ of the information complexity density, a random variable with information complexity as its expected value. For protocols with bounded number of rounds, we give a simulation protocol that yields a matching upper bound. Thus, it is not information complexity but $\lambda_\epsilon$ that governs the distributional communication complexity. As applications of our bounds...

Communication complexity of promise problems and their applications to finite automata

Gruska, Jozef; Qiu, Daowen; Zheng, Shenggen
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 30/09/2013
Relevância na Pesquisa
36.43%
Equality and disjointness are two of the most studied problems in communication complexity. They have been studied for both classical and also quantum communication and for various models and modes of communication. Buhrman et al. [Buh98] proved that the exact quantum communication complexity for a promise version of the equality problem is ${\bf O}(\log {n})$ while the classical deterministic communication complexity is $n+1$ for two-way communication, which was the first impressively large (exponential) gap between quantum and classical (deterministic and probabilistic) communication complexity. If an error is tolerated, both quantum and probabilistic communication complexities for equality are ${\bf O}(\log {n})$. However, even if an error is tolerated, the gaps between quantum (probabilistic) and deterministic complexity are not larger than quadratic for the disjointness problem. It is therefore interesting to ask whether there are some promise versions of the disjointness problem for which bigger gaps can be shown. We give a positive answer to such a question. Namely, we prove that there exists an exponential gap between quantum (even probabilistic) communication complexity and classical deterministic communication complexity of some specific versions of the disjointness problem. Klauck [Kla00] proved...

Approximation for the Path Complexity of Binary Search Tree

Doshi, Nishant
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 18/04/2014
Relevância na Pesquisa
36.43%
The complexity of an algorithm is an important parameter to determine its effi-ciency. They are of different types viz. Time complexity, Space complexity, etc. However, none of them consider the execution path as a complexity measure. Ashok et al, firstly proposed the notion of the Path Complexity of a pro-gram/algorithm, which defined based on the number of execution paths as a function of the input size. However, the notion of path complexity of the pro-gram, cannot apply to the object-oriented environment. Therefore, Anupam et al, has extended the notion of path complexity to the class as follows. The notion of the state of the class is defined based on structural representation (aka state) of the class. The class contains data members and data operations. It considers only those data operations that change the state of the class. The path complexity of the class is defined to be the number of valid input sequences, each of them con-taining valid data operations. Anupam et al, had applied this notion to the class Stack. However, the stack is basic and simple data structures. Therefore, in this research we have used a more complex class to understand the path complexity behavior in the object oriented environment. Binary Search Tree (BST) is one of the well known (and more complex too) data structure...

Query complexity in expectation

Kaniewski, Jedrzej; Lee, Troy; de Wolf, Ronald
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 26/11/2014
Relevância na Pesquisa
36.44%
We study the query complexity of computing a function f:{0,1}^n-->R_+ in expectation. This requires the algorithm on input x to output a nonnegative random variable whose expectation equals f(x), using as few queries to the input x as possible. We exactly characterize both the randomized and the quantum query complexity by two polynomial degrees, the nonnegative literal degree and the sum-of-squares degree, respectively. We observe that the quantum complexity can be unboundedly smaller than the classical complexity for some functions, but can be at most polynomially smaller for functions with range {0,1}. These query complexities relate to (and are motivated by) the extension complexity of polytopes. The linear extension complexity of a polytope is characterized by the randomized communication complexity of computing its slack matrix in expectation, and the semidefinite (psd) extension complexity is characterized by the analogous quantum model. Since query complexity can be used to upper bound communication complexity of related functions, we can derive some upper bounds on psd extension complexity by constructing efficient quantum query algorithms. As an example we give an exponentially-close entrywise approximation of the slack matrix of the perfect matching polytope with psd-rank only 2^{n^{1/2+epsilon}}. Finally...

Partition Arguments in Multiparty Communication Complexity

Draisma, Jan; Kushilevitz, Eyal; Weinreb, Enav
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 30/09/2009
Relevância na Pesquisa
36.43%
Consider the "Number in Hand" multiparty communication complexity model, where k players holding inputs x_1,...,x_k in {0,1}^n communicate to compute the value f(x_1,...,x_k) of a function f known to all of them. The main lower bound technique for the communication complexity of such problems is that of partition arguments: partition the k players into two disjoint sets of players and find a lower bound for the induced two-party communication complexity problem. In this paper, we study the power of partition arguments. Our two main results are very different in nature: (i) For randomized communication complexity, we show that partition arguments may yield bounds that are exponentially far from the true communication complexity. Specifically, we prove that there exists a 3-argument function f whose communication complexity is Omega(n), while partition arguments can only yield an Omega(log n) lower bound. The same holds for nondeterministic communication complexity. (ii) For deterministic communication complexity, we prove that finding significant gaps between the true communication complexity and the best lower bound that can be obtained via partition arguments, would imply progress on a generalized version of the "log-rank conjecture" in communication complexity. We conclude with two results on the multiparty "fooling set technique"...

R\'enyi Information Complexity and an Information Theoretic Characterization of the Partition Bound

Prabhakaran, Manoj M.; Prabhakaran, Vinod M.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 25/11/2015
Relevância na Pesquisa
36.46%
We introduce a new information-theoretic complexity measure $IC_\infty$ for 2-party functions which is a lower-bound on communication complexity, and has the two leading lower-bounds on communication complexity as its natural relaxations: (external) information complexity ($IC$) and logarithm of partition complexity ($\text{prt}$) which have so far appeared conceptually quite different from each other. $IC_\infty$ is an external information complexity based on R\'enyi mutual information of order infinity. In the definition of $IC_\infty$, relaxing the order of R\'enyi mutual information from infinity to 1 yields $IC$, while $\log \text{prt}$ is obtained by replacing protocol transcripts with what we term "pseudotranscripts," which omits the interactive nature of a protocol, but only requires that the probability of any transcript given the inputs $x$ and $y$ to the two parties, factorizes into two terms which depend on $x$ and $y$ separately. Further understanding $IC_\infty$ might have consequences for important direct-sum problems in communication complexity, as it lies between communication complexity and information complexity. We also show that applying both the above relaxations simultaneously to $IC_\infty$ gives a complexity measure that is lower-bounded by the (log of) relaxed partition complexity...

On Arthur Merlin Games in Communication Complexity

Klauck, Hartmut
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 03/01/2011
Relevância na Pesquisa
36.41%
We show several results related to interactive proof modes of communication complexity. First we show lower bounds for the QMA-communication complexity of the functions Inner Product and Disjointness. We describe a general method to prove lower bounds for QMA-communication complexity, and show how one can 'transfer' hardness under an analogous measure in the query complexity model to the communication model using Sherstov's pattern matrix method. Combining a result by Vereshchagin and the pattern matrix method we find a communication problem with AM-communication complexity $O(\log n)$, PP-communication complexity $\Omega(n^{1/3})$, and QMA-communication complexity $\Omega(n^{1/6})$. Hence in the world of communication complexity noninteractive quantum proof systems are not able to efficiently simulate co-nondeterminism or interaction. These results imply that the related questions in Turing machine complexity theory cannot be resolved by 'algebrizing' techniques. Finally we show that in MA-protocols there is an exponential gap between one-way protocols and two-way protocols (this refers to the interaction between Alice and Bob). This is in contrast to nondeterministic, AM-, and QMA-protocols, where one-way communication is essentially optimal.; Comment: 19 pages

Separations in Query Complexity Based on Pointer Functions

Ambainis, Andris; Balodis, Kaspars; Belovs, Aleksandrs; Lee, Troy; Santha, Miklos; Smotrovs, Juris
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.45%
In 1986, Saks and Wigderson conjectured that the largest separation between deterministic and zero-error randomized query complexity for a total boolean function is given by the function $f$ on $n=2^k$ bits defined by a complete binary tree of NAND gates of depth $k$, which achieves $R_0(f) = O(D(f)^{0.7537\ldots})$. We show this is false by giving an example of a total boolean function $f$ on $n$ bits whose deterministic query complexity is $\Omega(n/\log(n))$ while its zero-error randomized query complexity is $\tilde O(\sqrt{n})$. We further show that the quantum query complexity of the same function is $\tilde O(n^{1/4})$, giving the first example of a total function with a super-quadratic gap between its quantum and deterministic query complexities. We also construct a total boolean function $g$ on $n$ variables that has zero-error randomized query complexity $\Omega(n/\log(n))$ and bounded-error randomized query complexity $R(g) = \tilde O(\sqrt{n})$. This is the first super-linear separation between these two complexity measures. The exact quantum query complexity of the same function is $Q_E(g) = \tilde O(\sqrt{n})$. These two functions show that the relations $D(f) = O(R_1(f)^2)$ and $R_0(f) = \tilde O(R(f)^2)$ are optimal...

Sample Complexity Bounds on Differentially Private Learning via Communication Complexity

Feldman, Vitaly; Xiao, David
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.42%
In this work we analyze the sample complexity of classification by differentially private algorithms. Differential privacy is a strong and well-studied notion of privacy introduced by Dwork et al. (2006) that ensures that the output of an algorithm leaks little information about the data point provided by any of the participating individuals. Sample complexity of private PAC and agnostic learning was studied in a number of prior works starting with (Kasiviswanathan et al., 2008) but a number of basic questions still remain open, most notably whether learning with privacy requires more samples than learning without privacy. We show that the sample complexity of learning with (pure) differential privacy can be arbitrarily higher than the sample complexity of learning without the privacy constraint or the sample complexity of learning with approximate differential privacy. Our second contribution and the main tool is an equivalence between the sample complexity of (pure) differentially private learning of a concept class $C$ (or $SCDP(C)$) and the randomized one-way communication complexity of the evaluation problem for concepts from $C$. Using this equivalence we prove the following bounds: 1. $SCDP(C) = \Omega(LDim(C))$, where $LDim(C)$ is the Littlestone's (1987) dimension characterizing the number of mistakes in the online-mistake-bound learning model. Known bounds on $LDim(C)$ then imply that $SCDP(C)$ can be much higher than the VC-dimension of $C$. 2. For any $t$...

Nearly optimal separations between communication (or query) complexity and partitions

Kothari, Robin
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 03/12/2015
Relevância na Pesquisa
36.43%
We show a nearly quadratic separation between deterministic communication complexity and the logarithm of the partition number, which is essentially optimal. This improves upon a recent power 1.5 separation of G\"o\"os, Pitassi, and Watson (FOCS 2015). In query complexity, we establish a nearly quadratic separation between deterministic (and even randomized) query complexity and subcube partition complexity, which is also essentially optimal. We also establish a nearly power 1.5 separation between quantum query complexity and subcube partition complexity, the first superlinear separation between the two measures. Lastly, we show a quadratic separation between quantum query complexity and one-sided subcube partition complexity. Our query complexity separations use the recent cheat sheet framework of Aaronson, Ben-David, and the author. Our query functions are built up in stages by alternating function composition with the cheat sheet construction. The communication complexity separation follows from lifting the query separation to communication complexity.; Comment: 13 pages

Lower Bounds on the Oracle Complexity of Nonsmooth Convex Optimization via Information Theory

Braun, Gábor; Guzmán, Cristóbal; Pokutta, Sebastian
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 19/07/2014
Relevância na Pesquisa
36.43%
We present an information-theoretic approach to lower bound the oracle complexity of nonsmooth black box convex optimization, unifying previous lower bounding techniques by identifying a combinatorial problem, namely string guessing, as a single source of hardness. As a measure of complexity we use distributional oracle complexity, which subsumes randomized oracle complexity as well as worst-case oracle complexity. We obtain strong lower bounds on distributional oracle complexity for the box $[-1,1]^n$, as well as for the $L^p$-ball for $p \geq 1$ (for both low-scale and large-scale regimes), matching worst-case lower bounds, and hence we close the gap between distributional complexity, and in particular, randomized complexity, and worst-case complexity. Furthermore, the bounds remain essentially the same for high-probability and bounded-error oracle complexity, and even for combination of the two, i.e., bounded-error high-probability oracle complexity. This considerably extends the applicability of known bounds.

Economic complexity, regime transition and sectoral forces: the impact of trade unions on democratization in Zimbabwe, South Africa and Zambia

McCorley, Ciara
Fonte: University of Limerick Publicador: University of Limerick
Tipo: info:eu-repo/semantics/doctoralThesis; all_ul_research; ul_published_reviewed; ul_theses_dissertations
ENG
Relevância na Pesquisa
36.44%
peer-reviewed; This thesis interrogates uncertainty in transitional politics in South Africa, Zambia, and Zimbabwe. It questions why some countries transition to democracy and some stagnate or revert to authoritarianism. To address the dual nature of political contingency and structural formations in transitional politics, it adopts a conceptual framework based on economic complexity, to ascertain the relationship between economic structures and the results of regime transition. This study engages with the extensive literature linking economic development and democracy throughout the world, to see if it can be applied to the recent and on-going transitional events across Africa. It identified trade union confederations as economically important actors whose political contingency was directly affected by the sectoral composition of each country’s economy. In other world regions, trade unions have been of import in determining transitional outcomes, and this thesis interrogated whether the same was true in three African countries. The concept of economic complexity was developed to offer a conceptual framework through which to understand transitional politics. It was argued that the more complex the economy, the more likely democracy was to emerge following transition because there would be more factors in play in the political-economic arena that could erode a regime’s relative power and thus bestow power onto other actors who could utilize it for regime change. In terms of indicators...