Search results for " Complexity"
showing 10 items of 623 documents
Random Feature Approximation for Online Nonlinear Graph Topology Identification
2021
Online topology estimation of graph-connected time series is challenging, especially since the causal dependencies in many real-world networks are nonlinear. In this paper, we propose a kernel-based algorithm for graph topology estimation. The algorithm uses a Fourier-based Random feature approximation to tackle the curse of dimensionality associated with the kernel representations. Exploiting the fact that the real-world networks often exhibit sparse topologies, we propose a group lasso based optimization framework, which is solve using an iterative composite objective mirror descent method, yielding an online algorithm with fixed computational complexity per iteration. The experiments con…
Inference of Spatio-Temporal Functions over Graphs via Multi-Kernel Kriged Kalman Filtering
2018
Inference of space-time varying signals on graphs emerges naturally in a plethora of network science related applications. A frequently encountered challenge pertains to reconstructing such dynamic processes, given their values over a subset of vertices and time instants. The present paper develops a graph-aware kernel-based kriged Kalman filter that accounts for the spatio-temporal variations, and offers efficient online reconstruction, even for dynamically evolving network topologies. The kernel-based learning framework bypasses the need for statistical information by capitalizing on the smoothness that graph signals exhibit with respect to the underlying graph. To address the challenge o…
Energy Efficiency Optimization for Multi-cell Massive MIMO : Centralized and Distributed Power Allocation Algorithms
2021
This paper investigates the energy efficiency (EE) optimization in downlink multi-cell massive multiple-input multiple-output (MIMO). In our research, the statistical channel state information (CSI) is exploited to reduce the signaling overhead. To maximize the minimum EE among the neighbouring cells, we design the transmit covariance matrices for each base station (BS). Specifically, optimization schemes for this max-min EE problem are developed, in the centralized and distributed ways, respectively. To obtain the transmit covariance matrices, we first find out the closed-form optimal transmit eigenmatrices for the BS in each cell, and convert the original transmit covariance matrices desi…
A fast recursive algorithm to compute local axial moments
2001
The paper describes a fast algorithm to compute local axial moments used in the algorithm of discrete symmetry transform (DST). The basic idea is grounded on fast recursive implementation of respective linear filters by using the so-called primitive kernel functions since the moment computation can be performed in the framework of linear filtering. The main result is that the computation of the local axial moments is independent of the kernel size, i.e. of the order O(1) per data point (pixel). This result is of relevance whenever the DST is used to face with real time computer vision problems. The experimental results confirm the time complexity predicted by the theory.
Correlations among Game of Thieves and other centrality measures in complex networks
2021
Social Network Analysis (SNA) is used to study the exchange of resources among individuals, groups, or organizations. The role of individuals or connections in a network is described by a set of centrality metrics which represent one of the most important results of SNA. Degree, closeness, betweenness and clustering coefficient are the most used centrality measures. Their use is, however, severely hampered by their computation cost. This issue can be overcome by an algorithm called Game of Thieves (GoT). Thanks to this new algorithm, we can compute the importance of all elements in a network (i.e. vertices and edges), compared to the total number of vertices. This calculation is done not in…
Opportunities and challenges of digitized discretionary practices: a public service worker perspective
2018
Abstract Public service workers exercise discretionary power during policy implementation. Due to an immense diffusion of information and communications technology (ICT) in public service provision, they are increasingly exposed to reforms aiming at more efficient and fair decision-making. Whereas extant literature has found that ICT can both enable and constrain public service workers' ability to exercise discretion, we know less about underlying explanations for these inconclusive findings. This paper addresses this research gap by exploring how and why public service workers react to digitized discretionary practices. We draw upon institutional logics to show the underlying consideration…
On Fuzziness, Its Homeland and Its Neighbour
2013
It has been frequently remembered (also in the invitation letter to contribute to the present volume) that in his 1962 paper [27] which is a sort of proto-manifesto of fuzzy sets [28], Zadeh among the possible names that could denote the new notion he was trying to introduce, basides fuzzy, mentioned the term cloudy. If he had chosen this last one as the name of the theory, today we had contributed to a volume On Cloudiness.
A metrics suite for evaluating agent-oriented architectures
2010
The Multi-agent Systems (MASs) paradigm continues to consolidate itself as a new branch of software engineering. Traditional software engineering strongly recommends to apply metrics in software developments. However, several research groups of experts in agent-oriented software engineering agree that classical software metrics and object-oriented metrics cannot directly measure the quality of MAS architectures. For this reason, this work proposes a suite of metrics to measure certain quality attributes of MAS architectures, considering agents and their organization. Most of these metrics are inspired by object-oriented metrics but they are adapted to agent-oriented concepts. Proposed metri…
Quantum counter automata
2011
The question of whether quantum real-time one-counter automata (rtQ1CAs) can outperform their probabilistic counterparts has been open for more than a decade. We provide an affirmative answer to this question, by demonstrating a non-context-free language that can be recognized with perfect soundness by a rtQ1CA. This is the first demonstration of the superiority of a quantum model to the corresponding classical one in the real-time case with an error bound less than 1. We also introduce a generalization of the rtQ1CA, the quantum one-way one-counter automaton (1Q1CA), and show that they too are superior to the corresponding family of probabilistic machines. For this purpose, we provide gene…
Assessing maintainability change over multiple software releases
2008
The focus of the paper is to reveal the relationships between software maintainability and other internal software quality attributes. The source code characteristics of five Java-based open-source software products are analyzed using the software measurement tool SoftCalc. The relationships between maintainability and internal quality attributes are identified based on the Pearson product moment correlation analysis. Our results show negative correlations between maintainability and some well-known internal software quality attributes, as well as the ones between maintainability and complexity metrics. Particularly, according to our results, the Number of Data Variables Declared and the De…