Contracts in Practice

Contracts are a form of lightweight formal specification embedded in the program text. Being executable parts of the code, they encourage programmers to devote proper attention to specifications, and help maintain consistency between specification and implementation as the program evolves. The present study investigates how contracts are used in the practice of software development. Based on an extensive empirical analysis of 21 contract-equipped Eiffel, C#, and Java projects totaling more than 260 million lines of code over 7700 revisions, it explores, among other questions: 1) which kinds of contract elements (preconditions, postconditions, class invariants) are used more often; 2) how contracts evolve over time; 3) the relationship between implementation changes and contract changes; and 4) the role of inheritance in the process. It has found, among other results, that: the percentage of program elements that include contracts is above 33% for most projects and tends to be stable over time; there is no strong preference for a certain type of contract element; contracts are quite stable compared to implementations; and inheritance does not significantly affect qualitative trends of contract usage

Construction contract policy: do we mean what we say?

Recent developments in contracting practice in the UK have built upon recommendations contained in highprofile reports, such as those by Latham and Egan. However, the New Engineering Contract (NEC), endorsed by Latham, is based upon principles of contract drafting that seem open to question. Any contract operates in the context of its legislative environment and current working practices. This report identifies eight contentious hypotheses in the literature on construction contracts and tests their validity in a sample survey that attracted 190 responses. The survey shows, among other things, that while partnership is a positive and useful idea, authoritative contract management is considered more effective and that “win-win” contracts, while desirable, are basically impractical. Further, precision and fairness in contracts are not easy to achieve simultaneously. While participants should know what is in their contracts, they should not routinely resort to legal action; and standard-form contracts should not seek to be universally applicable. Fundamental changes to drafting policy should be undertaken within the context of current legal contract doctrine and with a sensitivity to the way that contracts are used in contemporary practice. Attitudes to construction contracting may seem to be changing on the surface, but detailed analysis of what lies behind apparent agreement on new ways of working reveals that attitudes are changing much more slowly than they appear to be

FACTORS AFFECTING CONSERVATION PRACTICE BEHAVIOR OF CRP PARTICIPANTS IN ALABAMA

This study examines the factors that affect conservation practice choices of CRP farmers in Alabama. From over 9,000 contracts enrolled in the state between 1986 and 1995, 594 were randomly selected for the study. A multiple-regression analysis was employed to analyze the data. Results indicate that education, ratio of cropland in CRP, farm size, gender, prior crop practice, and geographic location of contract had a significant influence on the choice of conservation practice adopted.conservation practices, Conservation Reserve Program, CRP contracts, cost share, erodible cropland, grass practice, land retirement, tree practice, Farm Management, Land Economics/Use,

Auctions for Infrastructure Concessions with Demand Uncertainty and Unknown Costs

Auction mechanisms commonly used in practice for awarding infrastructure concession contracts induce a bias towards the selection of concessionaires who are optimistic about demand, but are not necessarily cost-efficient. This helps to explain the frequent renegotiation of concessions observed in practice. This paper shows that the fixed-term nature of contracts is the key element for selection errors, and it proposes a better alternative mechanism based on flexible-term contracts. This new auction mechanism reduces the probability of selection errors and contract renegotiation, and it is simple enough to constitute a good option for concessions in sectors like transport and public utilities.concessions, auctions, renegotiation, infrastructure

Designing Secure Ethereum Smart Contracts: A Finite State Machine Based Approach

The adoption of blockchain-based distributed computation platforms is growing fast. Some of these platforms, such as Ethereum, provide support for implementing smart contracts, which are envisioned to have novel applications in a broad range of areas, including finance and Internet-of-Things. However, a significant number of smart contracts deployed in practice suffer from security vulnerabilities, which enable malicious users to steal assets from a contract or to cause damage. Vulnerabilities present a serious issue since contracts may handle financial assets of considerable value, and contract bugs are non-fixable by design. To help developers create more secure smart contracts, we introduce FSolidM, a framework rooted in rigorous semantics for designing con- tracts as Finite State Machines (FSM). We present a tool for creating FSM on an easy-to-use graphical interface and for automatically generating Ethereum contracts. Further, we introduce a set of design patterns, which we implement as plugins that developers can easily add to their contracts to enhance security and functionality

A Theoretical Approach to Dual Practice Regulations in the Health Sector

Internationally, there is wide cross-country heterogeneity in government responses to dual practice in the health sector. This paper provides a uniform theoretical framework to analyze and compare some of the most common regulations. We focus on three interventions: banning dual practice, offering rewarding contracts to public physicians, and limiting dual practice (including both limits to private earnings of dual providers and limits to involvement in private activities). An ancillary objective of the paper is to investigate whether regulations that are optimal for developed countries are adequate for developing countries as well. Our results offer theoretical support for the desirability of different regulations in different economic environments.Dual practice, optimal contracts, physicians' incentives, regulations.

Incentive Contracts in Team Sports - Theory and Practice

A comparison of incentive clauses of players’ contracts in German soccer and clauses used in the NFL and NBA shows considerable differences. Against the background of principle-agent theory we have a closer look at these incentive systems. In contrast to other industries it is easy to observe the employees’ effort in team sports. Therefore, it would be desirable to set incentives for players based on their individual effort. We show that there are reasons why incentive clauses in professional German soccer, the NBA and the NFL are not directly based on effort. We argue that there are two main reasons: Firstly, efficient incentives are complementarily provided by subjective and objective performance measures. Secondly, cooperation amongst team members is essential in team sports.sports, labor contracts, agency theory, incentives,

Overview and classification of coordination contracts within forward and reverse supply chains

Among coordination mechanisms, contracts are valuable tools used in both theory and practice to coordinate various supply chains. The focus of this paper is to present an overview of contracts and a classification of coordination contracts and contracting literature in the form of classification schemes. The two criteria used for contract classification, as resulted from contracting literature, are transfer payment contractual incentives and inventory risk sharing. The overview classification of the existing literature has as criteria the level of detail used in designing the coordination models with applicability on the forward and reverse supply chains.Coordination contracts; forward supply chain; reverse supply chain

The license/contract dichotomy in open licenses: a comparative analysis

The paper looks at the legal nature of so-called open licenses – agreements designed to provide permissions to users and publishers through “some rights reserved” clauses. The article starts with the assertion that copyright licenses are contracts in Civil Law jurisdictions, and looks at the opposing views and practice in Common Law jurisdictions. The article particularly looks at recent case law in the United States which deals specifically with the issue, and concludes that there is now a clear jurisdictional split between both traditions on whether these licenses are contracts