scholarly journals Deferred On-Line Bipartite Matching

10.37236/5756 ◽  
2018 ◽  
Vol 25 (2) ◽  
Author(s):  
Jakub Kozik ◽  
Grzegorz Matecki
Keyword(s):  
Competitive Ratio ◽  
Bipartite Graphs ◽  
Deterministic Algorithm ◽  
The Other ◽  
Bipartite Matching ◽  
Classical Version ◽  
New Model ◽  
On Line

We present a new model for the problem of on-line matching on bipartite graphs. Suppose that one part of a graph is given, but the vertices of the other part are presented in an on-line fashion. In the classical version, each incoming vertex is either irrevocably matched to a vertex from the other part or stays unmatched forever. In our version, an algorithm is allowed to match the new vertex to a group of elements (possibly empty). Later on, the algorithm can decide to remove some vertices from the group and assign them to another (just presented) vertex, with the restriction that each element belongs to at most one group. We present an optimal (deterministic) algorithm for this problem and prove that its competitive ratio equals $1-\pi/\cosh(\frac{\sqrt{3}}{2}\pi)\approx 0.588$.

Allocation Problems in Ride-sharing Platforms

2021 ◽  
Vol 9 (3) ◽  
pp. 1-17
Author(s):  
John P. Dickerson ◽  
Karthik A. Sankararaman ◽  
Aravind Srinivasan ◽  
Pan Xu
Keyword(s):  
Adaptive Algorithm ◽  
Competitive Ratio ◽  
Data Driven ◽  
Matching Markets ◽  
Prior Work ◽  
Bipartite Matching ◽  
New Model ◽  
Ride Sharing ◽  
Online Matching ◽  
Over Time

Bipartite-matching markets pair agents on one side of a market with agents, items, or contracts on the opposing side. Prior work addresses online bipartite-matching markets, where agents arrive over time and are dynamically matched to a known set of disposable resources. In this article, we propose a new model, Online Matching with (offline) Reusable Resources under Known Adversarial Distributions ( OM-RR-KAD ) , in which resources on the offline side are reusable instead of disposable; that is, once matched, resources become available again at some point in the future. We show that our model is tractable by presenting an LP-based non-adaptive algorithm that achieves an online competitive ratio of ½-ϵ for any given constant ϵ > 0. We also show that no adaptive algorithm can achieve a ratio of ½ + o (1) based on the same benchmark LP. Through a data-driven analysis on a massive openly available dataset, we show our model is robust enough to capture the application of taxi dispatching services and ride-sharing systems. We also present heuristics that perform well in practice.

Reading About Persons: The Effects of Conjunctions on the Mental Representation of Person Descriptions

2008 ◽  
Vol 67 (1) ◽  
pp. 5-18 ◽  
Author(s):  
Sabine Krolak-Schwerdt ◽  
Margret Wintermantel ◽  
Nadine Junker ◽  
Julia Kneer
Keyword(s):  
Mental Representation ◽  
The Other ◽  
Person Memory ◽  
Causal Connections ◽  
Single Person ◽  
On Line

Three experiments investigated the processing of person descriptions that consisted of a number of statements about the characteristics of a person. In one condition, each statement referred to a single person attribute and in the other condition, causal and additive conjunctions to verbally link the statements were introduced. Evidence was found that the introduction of verbal links enhanced participants’ memory about the characteristics of the described person. On-line measures of processing showed that the comprehension of person information was strongly facilitated by the introduction of verbal links. Furthermore, the results were due to the introduction of causal connections between person attributes. These findings are discussed in terms of their implications for models of person memory and representation.

Getting Over Athens

2018 ◽  
Author(s):  
Nicolas Wiater
Keyword(s):  
Roman Empire ◽  
The Other ◽  
The Political ◽  
New Model ◽  
Dionysius Of Halicarnassus ◽  
The One

This chapter examines the ambivalent image of Classical Athens in Dionysius of Halicarnassus’ Roman Antiquities. This image reflects a deep-seated ambiguity of Dionysius’ Classicist ideology: on the one hand, there is no question for Dionysius that Athenocentric Hellenicity failed, and that the Roman empire has superseded Athens’ role once and for all as the political and cultural centre of the oikoumene. On the other, Dionysius accepted Rome’s supremacy as legitimate partly because he believed (and wanted his readers to believe) her to be the legitimate heir of Classical Athens and Classical Athenian civic ideology. As a result, Dionysius develops a new model of Hellenicity for Roman Greeks loyal to the new political and cultural centre of Rome. This new model of Greek identity incorporates and builds on Classical Athenian ideals, institutions, and culture, but also supersedes them.

scholarly journals NHPP Software Reliability Model with Inflection Factor of the Fault Detection Rate Considering the Uncertainty of Software Operating Environments and Predictive Analysis

Symmetry ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 521 ◽  
Author(s):  
Song ◽  
Chang ◽  
Pham
Keyword(s):  
Fault Detection ◽  
Software Reliability ◽  
Detection Rate ◽  
The Other ◽  
Reliability Model ◽  
New Model ◽  
Software Failures ◽  
Software Failure ◽  
Software Reliability Model ◽  
Operating Environments

The non-homogeneous Poisson process (NHPP) software has a crucial role in computer systems. Furthermore, the software is used in various environments. It was developed and tested in a controlled environment, while real-world operating environments may be different. Accordingly, the uncertainty of the operating environment must be considered. Moreover, predicting software failures is commonly an important part of study, not only for software developers, but also for companies and research institutes. Software reliability model can measure and predict the number of software failures, software failure intervals, software reliability, and failure rates. In this paper, we propose a new model with an inflection factor of the fault detection rate function, considering the uncertainty of operating environments and analyzing how the predicted value of the proposed new model is different than the other models. We compare the proposed model with several existing NHPP software reliability models using real software failure datasets based on ten criteria. The results show that the proposed new model has significantly better goodness-of-fit and predictability than the other models.

English Metre Once More

PMLA ◽  
1948 ◽  
Vol 63 (1) ◽  
pp. 293-326
Author(s):  
Evelyn H. Scholl
Keyword(s):  
The Other ◽  
English School ◽  
English Verse ◽  
On Line ◽  
The Subject

Although hundreds of books and articles have been written on the subject, there is still no agreement upon the question: What is the basis of English metre? There have been three schools of metrics: that of a strict count of syllables; that of accent; and that of equal times. The latest work which I have found to consider a strict count of syllables the sole basis of English metre was published in Heidelberg in 1902. But both of the other schools have their representatives today. It is my purpose to raise the question once more, and to throw light upon it from a hitherto unexplored source of unusual value, The English School of Lutenist Song Writers. I hope to show that the theory of equal times marked by stress best explains the varying phenomena of modern English verse, and especially the inclusion in metrical verse of such extremely irregular poems as “The Listeners” by De la Mare. And I hope also to clarify several metrical terms: the so-called “trochaic substitution” in iambic metre, the “caesura,” and the “run-on line.”

scholarly journals A Competitive Ratio for Quantifying Competition Between Intercrops

1980 ◽  
Vol 16 (2) ◽  
pp. 117-125 ◽  
Author(s):  
R. W. Willey ◽  
M. R. Rao
Keyword(s):  
Competitive Ratio ◽  
Competitive Ability ◽  
Maximum Yield ◽  
The Other ◽  
Competitive Balance ◽  
Crop Competition

SUMMARYA simple competitive ratio (CR) is proposed as a measure of intercrop competition, to indicate the number of times by which one component crop is more competitive than the other. Intercropping data show that this CR term could be useful in (i) comparing the competitive ability of different crops, (ii) measuring competitive changes within a given combination, (iii) identifying which plant characters are associated with competitive ability, and (iv) determining what competitive balance between components is most likely to give maximum yield advantages.

Cycles in symbol production? A new model to explain concentration, diversity and innovation in the music industry

Popular Music ◽  
1995 ◽  
Vol 14 (1) ◽  
pp. 55-93 ◽  
Author(s):  
Michael Christianen
Keyword(s):  
Negative Correlation ◽  
Music Industry ◽  
The Other ◽  
Recording Industry ◽  
Cultural Goods ◽  
New Model ◽  
Advantages And Disadvantages ◽  
Factors Influencing ◽  
Using Data ◽  
The One

With the publication of the article ‘Cycles in symbol production’ (Peterson and Berger 1975) a discussion started concerning the advantages and disadvantages of the production of cultural goods under market conditions. The analysis by Peterson and Berger showed a negative correlation between concentration in the recording industry, on the one hand, and the diversity and innovativeness of the music, on the other. Repetition of the analysis using data from the 1980s (Burnett 1990; Lopes 1992) has shown that for this period Peterson and Berger's hypotheses should be rejected. Is there a connection between concentration and diversity and innovation? Are there cycles in symbol production? There seems to be no conclusive answer. In this article, I will attempt to clear up this matter. First, I will repeat the analysis of the relation between concentration and diversity/innovation, using the same model as Peterson and Berger, but with different definitions for the variables concentration, diversity and innovation. Then I will suggest a new model, which can be helpful in uncovering other factors influencing diversity and innovation in the music industry. I will come to that later. Let me first give the reader a brief overview of previous research.

measurements. This paper is confined to the different forms of sampling odourous gases for olfactometric measurements and the problems involved. It refers to existing guidelines for olfactometric measurements in the countries of the EEC, as well. 2. TYPES OF SAMPLING Samples of odourous gas may be collected in unconcentrated or concentrated form. Concentrated sampling is usually neces­ sary when gas chromatography or other chemical analytical meth­ ods are to be used. Unconcentrated sampling is provided if o-dour threshold concentrations are required (2). Depending on the type of olfactometer used dynamic sam­ pling or static sampling are provided. The principle of dynam­ ic sampling is shown in Figure 1. It requires a part-flow of the odourous gas to be continoulsy extracted from the source and subsequently directed to the olfactometer. This sampling method implies that the measurements are carried out close to the source. An advantage of the method is that there is the possibility of controlling a process, directly, and in case of the break-down of the process this can be noticed right away. A disadvantage of the dynamic method is that odour sources that are not readily accessible require a relatively great ef­ fort in order to install the olfactometer and suitable sam­ pling pipes which often should be insulated or heated to avoid adsorption or condensation (3). When static sampling is used a partial stream of the o-dourous air is collected in a sampling vessel. Samples are taken from this vessel or bag to dilute the odourous air for the olfactometer using syringes or on-line tubings. When using this method odour measurement with the panel can be carried out at any arbitrary location, if the vessel is a transport­ able one. An example for static sampling is given in Figure 2. 3. PROBLEMS OF SAMPLING the main problems encountered when sampling odourous air derive from surface effects of the sampling tubes and vessels, namely by - adsorption, - desorption, and - condensation. This depends mainly on the material of the tube, the vessel or the bag (adsorption) or on the nature of the gas, whether it is hot and/or containes a high amount of humidity (condensa­ tion). On the other hand the sample can be altered by trace components bleeding from the material of the walls of the ves­ sel or the tube (desorption). The following factors are to be observed for valid static sampli ng. aTTTToTce of_m£teri aj_ For tWe sampling of odourous gases glas vessels, stain­ less steel tanks (4) and flexible plastic bags (5) were tested. The initial concentrations of the test gases decrease consider­ ably with storage time in glass and steel vessels. In recent years bags made of Polyethylene(6), Teflon (3) and Tedlar (7), (8) were usually used. Figure 3 shows a graph from SCHUETZLE

1986 ◽  
pp. 59-59
Keyword(s):  
Gas Chromatography ◽  
Storage Time ◽  
Dynamic Method ◽  
The Other ◽  
Plastic Bags ◽  
Steel Tanks ◽  
On Line ◽  
Arbitrary Location ◽  
Adsorption Desorption ◽  
Trace Components

scholarly journals Determination of the delivered hemodialysis dose using standard methods and on-line clearance monitoring

2006 ◽  
Vol 63 (8) ◽  
pp. 743-747 ◽  
Author(s):  
Vlastimir Vlatkovic ◽  
Biljana Stojimirovic
Keyword(s):  
Cumulative Effect ◽  
Chronic Hemodialysis ◽  
Reduction Ratio ◽  
The Other ◽  
Treatment Quality ◽  
Monitoring Methods ◽  
Dialysis Dose ◽  
Co Morbidity ◽  
On Line ◽  
Urea Reduction Ratio

Background/aim: Delivered dialysis dose has a cumulative effect and significant influence upon the adequacy of dialysis, quality of life and development of co-morbidity at patients on dialysis. Thus, a great attention is given to the optimization of dialysis treatment. On-line Clearance Monitoring (OCM) allows a precise and continuous measurement of the delivered dialysis dose. Kt/V index (K = dialyzer clearance of urea; t = dialysis time; V = patient's total body water), measured in real time is used as a unit for expressing the dialysis dose. The aim of this research was to perform a comparative assessment of the delivered dialysis dose by the application of the standard measurement methods and a module for continuous clearance monitoring. Methods. The study encompassed 105 patients who had been on the chronic hemodialysis program for more than three months, three times a week. By random choice, one treatment per each controlled patient was taken. All the treatments understood bicarbonate dialysis. The delivered dialysis dose was determined by the calculation of mathematical models: Urea Reduction Ratio (URR) singlepool index Kt/V (spKt/V) and by the application of OCM. Results. Urea Reduction Ratio was the most sensitive parameter for the assessment and, at the same time, it was in the strongest correlation with the other two, spKt/V indexes and OCM. The values pointed out an adequate dialysis dose. The URR values were significantly higher in women than in men, p < 0.05. The other applied model for the delivered dialysis dose measurement was Kt/V index. The obtained values showed that the dialysis dose was adequate, and that, according to this parameter, the women had significantly better dialysis, then the men p < 0.05. According to the OCM, the average value was slightly lower than the adequate one. The women had a satisfactory dialysis according to this index as well, while the delivered dialysis dose was insufficient in men. The difference between the women and the men was significant. Conclusion. The application of OCM has shown that it is the most rigorous parameter for the assessment of adequacy and that its regular use would contribute to increasing of the delivered dialysis dose and improvement of the treatment quality.

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