scholarly journals The computational complexity of multi-level linear programs

1992 ◽  
Vol 34 (1) ◽  
pp. 13-19 ◽  
Author(s):  
Charles Blair
Keyword(s):  
Computational Complexity ◽  
Linear Programs ◽  
Multi Level

Nearby Phase Search Algorithm with Reduced Complexity for Higher Order QAM Formats

2013 ◽  
Vol 760-762 ◽  
pp. 1869-1873
Author(s):  
Li Min Xia ◽  
Xian Zhou ◽  
Dong Yan ◽  
Na Na Zhang ◽  
Xiao Yun Wu
Keyword(s):  
Computational Complexity ◽  
Bit Error Rate ◽  
High Speed ◽  
Optical Transmission ◽  
Search Algorithm ◽  
Estimation Algorithm ◽  
Coherent Receivers ◽  
Multi Level ◽  
Reduced Complexity ◽  
Laser Line Width

This paper proposes a nearby phase search (NPS) algorithm based on BPS estimation algorithm in optical coherent receivers. And its suitable for arbitrary multi-level modulation. Making use of the continuity of phase change, the proposed NPS algorithm is applied to process nearby symbols by taking the pre-estimation phase of each symbol block as reference point. Compared to the traditional blind phase search (BPS) algorithm and its improved two-stage BPS algorithm, the performance of the proposed NPS algorithm is greatly improved in ultra-high speed coherent optical transmission system. By the simulation, the effectiveness and feasibility of the proposed algorithm are demonstrated in 28GBaud 16-QAM and 64-QAM system. Its shown that the computational complexity of the NPS algorithm greatly reduces in the guarantee of laser line width tolerance and bit error rate.

Core Pricing in Combinatorial Exchanges with Financially Constrained Buyers: Computational Hardness and Algorithmic Solutions

2021 ◽  
Author(s):  
Martin Bichler ◽  
Stefan Waldherr
Keyword(s):  
Computational Complexity ◽  
Core Stability ◽  
Mixed Integer ◽  
Polynomial Hierarchy ◽  
Budget Constraints ◽  
Linear Programs ◽  
Market Outcomes ◽  
Constraint Generation ◽  
Price Functions ◽  
Realistic Problem

The computation of market equilibria is a fundamental and practically relevant problem. Although we know the computational complexity and the types of price functions necessary for combinatorial exchanges with quasilinear preferences, the respective literature does not consider financially constrained buyers. We show that computing market outcomes that respect budget constraints but are core stable is a problem in the second level of the polynomial hierarchy. Problems in this complexity class are rare, but ignoring budget constraints can lead to significant efficiency losses and instability. We introduce mixed integer bilevel linear programs (MIBLP) to compute core-stable market outcomes and provide effective column and constraint generation algorithms to solve these problems. Although full core stability quickly becomes intractable, we show that realistic problem sizes can actually be solved if the designer limits attention to deviations of small coalitions. This n-coalition stability is a practical approach to tame the computational complexity of the general problem and at the same time provides a reasonable level of stability for markets in the field where buyers have budget constraints.

scholarly journals Comparative Study on Thresholding

2011 ◽  
pp. 73-77
Author(s):  
K.C. Singh ◽  
Lalit Mohan Satapathy ◽  
Bibhudatta Dash ◽  
S.K. Routray
Keyword(s):  
Computational Complexity ◽  
Comparative Study ◽  
Hierarchical Cluster ◽  
Multilevel Thresholding ◽  
Clustering Method ◽  
Good Separation ◽  
Robust Estimate ◽  
Clear Separation ◽  
Cluster Organization ◽  
Multi Level

Criterion based thresholding algorithms are simple and effective for two-level thresholding. However, if a multilevel thresholding is needed, the computational complexity will exponentially increase and the performance may become unreliable. In this approach, a novel and more effective method is used for multilevel thresholding by taking hierarchical cluster organization into account. Developing a dendogram of gray levels in the histogram of an image, based on the similarity measure which involves the inter-class variance of the clusters to be merged and the intra-class variance of the new merged cluster . The bottom-up generation of clusters employing a dendogram by the proposed method yields good separation of the clusters and obtains a robust estimate of the threshold. Such cluster organization will yield a clear separation between object and background even for the case of nearly unimodal or multimodal histogram. Since the hierarchical clustering method performs an iterative merging operation, it is extended to multilevel thresholding problem by eliminating grouping of clusters when the pixel values are obtained from the expected numbers of clusters. This paper gives a comparison on Otsu’s & Kwon’s criterion with hierarchical based multi-level thresholding.

Comparison of Image Decompositions Through Inverse Difference and Laplacian Pyramids

2015 ◽  
Vol 6 (1) ◽  
pp. 19-38 ◽  
Author(s):  
Roumen Kountchev ◽  
Stuart Rubin ◽  
Mariofanna Milanova ◽  
Roumiana Kountcheva
Keyword(s):  
Image Processing ◽  
Fourier Transform ◽  
Computational Complexity ◽  
Image Representation ◽  
Quantization Noise ◽  
Laplacian Pyramid ◽  
Image Transfer ◽  
Multi Level ◽  
Real Time Applications ◽  
The Fourier Transform

In this work, the Inverse Difference Pyramid (IDP) and its modification – the Reduced IDP (RIDP), are compared and evaluated with the famous Laplacian Pyramid (LP) for multi-level decomposition of digital images. The comparison comprises: the structures of LP and IDP, the image representation through LP and IDP in the pixel space and in the spectrum space of the Fourier transform, the efficiency of both transforms for the aims of the progressive image transfer, the LP and the IDP computation graphs and the evaluation of the computational complexity of the algorithms for the 3-level reduced LP and the 3-level reduced IDP. The influence of the quantization noise on both decompositions is also analyzed. On the basis of the comparison are outlined the basic advantages of the RIDP for pipeline image processing. The results obtained could be used for the design of coders for image compression, aimed at real-time applications, etc.

Verlaufsanalyse wöchentlicher Selbst- und Fremdeinschätzungen in der Langzeittherapie suchtkranker Jugendlicher

2019 ◽  
Vol 47 (2) ◽  
pp. 126-137
Author(s):  
Ferdinand Keller ◽  
Tatjana Stadnitski ◽  
Jakob Nützel ◽  
Renate Schepker
Keyword(s):  
Allen Vier ◽  
Multi Level

Zusammenfassung. Fragestellung: Über Veränderungen in der emotionalen Befindlichkeit von Jugendlichen während einer Suchttherapie ist wenig bekannt. Methode: Die Jugendlichen füllten wöchentlich einen entsprechenden Fragebogen aus, analog ihre Bezugsbetreuer eine parallelisierte Kurzfassung. Von 42 Jugendlichen liegen insgesamt 853 Bogen und von den Bezugsbetreuern 708 Bogen vor. Die Fragebogen wurden zunächst faktorenanalytisch hinsichtlich ihrer Dimensionalität ausgewertet, anschließend wurden gruppenbezogene Verlaufsanalysen (Multi-Level-Modelle) und Abhängigkeitsanalysen auf Einzelfallebene (Zeitreihenanalysen) durchgeführt. Ergebnisse: Im Jugendlichenfragebogen ergaben sich vier Faktoren: negative Befindlichkeit, Wertschätzung von Therapie/Betreuung, Motivation und Suchtdynamik. Die Übereinstimmung zwischen den Jugendlichen- und der (einfaktoriellen) Betreuereinschätzung fiel insgesamt niedrig bis mäßig aus, brachte aber auf Einzelfallebene differenziertere Ergebnisse. Im Verlauf nahmen die Werte auf allen vier Jugendlichenskalen ab. Einzig der Verlauf der Wertschätzung in der Eingewöhnungsphase war prädiktiv für den späteren Abbruch der Maßnahme: Bei den Abbrechern nahm die Wertschätzung ab, während sie bei den Beendern initial stieg. Schlussfolgerungen: Der bedeutsamste Faktor in Bezug auf die Therapiebeendigung suchtkranker Jugendlicher scheint die Wertschätzung von Therapie/Betreuung zu sein, während die Motivation jugendtypische Schwankungen aufweist. Der Suchtdynamik kam eine deutlich weniger bedeutende Rolle zu als allgemein angenommen. Programme in der Langzeittherapie sollten die Wertschätzung von Therapie/Betreuung künftig mehr fokussieren als die Suchtdynamik.

A Multi-level Measure Of Safety Climate And Associations With Safety Behaviors In The Fire Service

2017 ◽  
Author(s):  
Todd D. Smith ◽  
Mari-Amanda Dyal ◽  
Yongjia Pu ◽  
Stephanie Dickinson ◽  
David M. DeJoy
Keyword(s):  
Safety Climate ◽  
Fire Service ◽  
Safety Behaviors ◽  
Multi Level
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