Scheduling jobs with values dependent on their completion times

The paper concerns two scheduling problems with job values and losses of job values (costs) dependent on job completion times. In the first problem, we consider scheduling jobs with stepwise values in parallel processor environment. In the stepwise value, there is given a number of moments at which the job value decreases and between them the job value is constant (thus, the value deteriorates over time). The maximized criterion is the total job value. We prove strong NP-hardness of a single processor case of the problem and construct a pseudo-polynomial time algorithm for a special case with fixed number of unrelated parallel processors and fixed number of common moments of job value changes. Additionally, for uniform and unrelated parallel processors we construct and experimentally test several heuristic algorithms based on the list strategy. The second problem is a single processor one with piecewise linear losses of job values (the loss increases over time). The minimized criterion is the total loss of job value. We prove strong NP-hardness of the problem and existence of a pseudo-polynomial time exact algorithm for its special case. We also construct some heuristic algorithms for this problem and verify experimentally their efficiency.     

Strip Clubs, “Secondary Effects” and Residential Property Prices

Municipalities regulate sexually oriented businesses (SOBs) through the “secondary effects” doctrine, which justifies limiting First Amendment speech protections inside SOBs. Negative effects of SOBs on nearby neighborhood quality are a frequently cited secondary effect. Little empirical evidence exists that SOBs generate such negative externalities. If SOBs generate negative externalities, then nearby property prices should decrease when a strip club opens. We estimate regression models of housing prices to determine the effect of new clubs on nearby residential property prices in Seattle, exploiting the termination of a 17‐year moratorium on openings and find no evidence that strip clubs have “secondary effects.”     

Programming for the Internet and Experiential Learning: a New Approach Incorporating a Constructed World

This paper reports on a novel approach taken by the author to the teaching of an Internet programming course targeted at final year diploma and second year degree students. The uniqueness of engineers and their identity is discussed, as is the self-constructed world and ways of knowing in which humankind operates. The novel approach to teaching a software-coding course, and this course’s underlying philosophies of learning, the approach taken in class-contact time, and the methods of interaction with the students are presented, along with the conventional structure, quantitative measures, outline, and assessment of the course. The effects and observations of approaches employed are discussed, and the quantitative outputs achieved are presented alongside the unquantifiable impressions, comments and positive feedback.     

Duality theory and pitfalls in the specification of technologies

Principles of duality enable the investigator to model the technology of a multiple-input-single- output firm either by means of a production function or a cost function. For empirical implementation, both alternatives employ the assumption of competitive market behaviour. Recently, functional forms have been developed which are sufficiently flexible to describe the substitution possibilities among factors when the technology consists of more than two factors. However, contrary to the strongly separable multi-factor Cobb-Douglas and CES forms, these functional forms are not self-dual. This poses the problem of choosing between two different maintained hypotheses. In this paper, we compare the inferences with respect to substitution possibilities obtained by imposing the two alternative specifications of a production function and a cost function on the same set of data. We find that they give very different inferences with respect to substitution possibilities between factors. Furthermore, these inferences continue to differ even when we explicitly adopt the position that both the production and cost functions are each approximations of the true technology.     

Semiotische und verbandstheoretische Grundzüge einer elementaren Statistik

Zusammenfassung Die Statistik wird als ein formalisiertes Sprachsystem gedeutet und verschiedene Statistikalgorithmen werden über einenBooleschen Verband gebildet. Es werden nur nichtstochastische Probleme behandelt.

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Summary Statistic is considered a formalized language system. Some statistical algorithms are interpreted in aBoolean lattice. Only nonstochastical problems are considered.

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Der erste Teil dieser Abhandlung über eine attributive Statistik alsBoolescher Verband wurde im Heft Nr. 2 (1964) der Metrika als Festbeitrag zum 80. Geburtstag des Jubilars Hofrat Prof. Dr. Dr. h. c.Wilhelm Winkler ver?ffentlicht. Statistische Ma?verb?nde erscheinen über eine quasiadditive Bewertung eingeführt. Im vorliegenden zweiten Teil der Arbeit werden die Beziehungen der Statistik zurβ-Informationstheorie und einer speziellen Semiotik kurz er?rtert und die Algebraisierungs-beziehungsweise Geometrisierungsversuche betreffend die statistischen Forschungsmethoden weitergeführt.     

Improving retirement adequacy through asset class prioritization

Highly risk-averse retirees are generally advised to adopt a fixed spending strategy such as the 4% withdrawal rule. To prevent the premature depletion of a retirement portfolio, the rule attempts to proxy as the ‘safe withdrawal rate’. But a constant withdrawal rate means that retirees accumulate unspent surpluses when markets outperform and face spending shortfalls when markets underperform. While a safe withdrawal rate can prevent spending shortfalls, the opportunity cost of unspent surpluses associated with this strategy can be extreme. We apply a range of basic investment decision rules to a retirement portfolio applying various withdrawal rates and examine the probability of shortfalls over a retirement horizon. Using a block bootstrap simulation technique, we examine decision rules relating to stock and bond investments. Our results show that retirement portfolios with a bias towards stocks coupled with a decision rule that sources withdrawals from bonds and cash before stocks significantly outperforms alternative withdrawal strategies, despite the inherent increase in volatility. This finding is in direct contrast to the safe withdrawal rate conventions used in contemporary financial advice models.     

Legal Minimum Wages and Employment Duration

We estimate the effect of minimum wages on employment duration using event history data from the 1988-1994 rounds of the National Longitudinal Survey of Youth. Existing literature takes two alternative tracks: Some studies predict reduced turnover due to rents created by minimum wages, others focus on the expected increase in turnover due to reduced job amenities and imperfect information. We find that for men, the net effect of a minimum wage depends on its magnitude relative to the typical wage in the local labor market. We find some evidence that where the minimum wage is low, separation rates for men hired at the minimum wage are reduced. We also find that as the relative value of the minimum wage rises, separation hazards increase. We interpret these findings as evidence that rents may accrue to minimum wage workers, but that the job matching process is undermined when the minimum wage binds.     

Institutions and Strategies: Trends and Obstacles to Recruiting Workers into Trade Unions in Poland

In this article, we examine the role of institutional context, organizational structures and trade union strategies in tempering membership decline in the number of trade unions in Poland. Empirical data include membership statistics collected for NSZZ Solidarno?? and 54 affiliates of two other largest trade union confederations (OPZZ and FZZ) supplemented by semi‐structured interviews with union leaders. In a decentralized collective bargaining system in Poland, a centralized trade union confederation (NSZZ Solidarno??) can more easily shift resources to efficiently organize workers than decentralized confederations, OPZZ and FZZ, whose development is mostly driven by competing trade unions representing narrower occupational groups. In conclusion, this observation is put in a broader context of the debates about trade union renewal in Eastern Europe.