Global well-posedness and stability of the inhomogeneous kinetic wave equation near vacuum

In this paper, we prove global in time existence, uniqueness and stability of mild solutions near vacuum for the 4-wave inhomogeneous kinetic wave equation, for Laplacian dispersion relation in dimension $d=2,3$. We also show that for non-negative initial data, the solution remains non-negative. This is achieved by connecting the inhomogeneous kinetic wave equation to the cubic part of a quantum Boltzmann-type equation with moderately hard potential and no collisional averaging.Comment: 17 page

Economics-driven Technical Debt Management

Technical debt is a metaphor, stemming from economics, that resembles the delivery of software at poor quality to getting a loan. On the one hand, the costs saved during development boost the liquidity of the company (in the form of principal); whereas on the other hand, the poor quality produces additional costs (in the form of interest) along maintenance. This PhD project focuses on the financial nature of TD, and attempts to bring knowledge from the mature field of economics into the TD community. In particular, as a first step the project delivered the first systematic literature review, focusing on the economics nature of TD—providing a financial glossary and a taxonomy of the employed financial methods. Next, we assessed the industrial perception of TD, gaining insights on the need to explore the sustainability of TD in the future, considering various parameters. On top of these exploratory contributions, the main innovation offer by the project is two-fold. First, we delivered a novel interest theory based on the Liquidity Preference theory, named FITTED, which we instantiated at the source code TD level. FITTED considers the structural quality distance of the artifact under assessment from a (hypothetical) optimal one, as well as the historical evolution of the artifact. The TD interest assessment has been successfully validated in an industrial setting; and has been validated as related to TD principal, which strengthens the financial cornerstone of the metaphor suggesting that interest is calculated as a fraction of the principal. Finally, we provided an approach for treating architectural decisions (that are related to TD) as a financial investment. The corresponding approach (namely: ADMIT) relies on the cost-benefit analysis, giving the ability to consider both technical (such as complexity) and financial parameters (such as market share). ADMIT has also been successfully validated in industry

Architectural decision-making as a financial investment:An industrial case study

Context Making architectural decisions is a crucial task but also very difficult, considering the scope of the decisions and their impact on quality attributes. To make matters worse, architectural decisions need to combine both technical and business factors, which are very dissimilar by nature. Objectives We provide a cost-benefit approach and supporting tooling that treats architectural decisions as financial investments by: (a) combining both technical and business factors; and (b) transforming the involved factors into currency, allowing their uniform aggregation. Apart from illustrating the method, we validate both the proposed approach and the tool, in terms of fitness for purpose, usability, and potential limitations. Method To validate the approach, we have performed a case study in a software development company, in the domain of low-energy embedded systems. We employed triangulation in the data collection phase of the case study, by performing interviews, focus groups, an observational session, and questionnaires. Results The results of the study suggested that the proposed approach: (a) provides a structured process for systematizing decision-making; (b) enables the involvement of multiple stakeholders, distributing the decision-making responsibility to more knowledgeable people; (c) uses monetized representations that are important for assessing decisions in a unified manner; and (d) enables decision reuse and documentation. Conclusions The results of the study suggest that architectural decision-making can benefit from treating this activity as a financial investment. The various benefits that have been identified from mixing financial and technological aspects are well-accepted from industrial stakeholders

The Perception of Technical Debt in the Embedded Systems Domain:An Industrial Case Study

Technical Debt Management (TDM) has drawn the attention of software industries during the last years, including embedded systems. However, we currently lack an overview of how practitioners from this application domain perceive technical debt. To this end, we conducted a multiple case study in the embedded systems industry, to investigate: (a) the expected life-time of components that have TD, (b) the most frequently occurring types of TD in them, and (c) the significance of TD against run-time quality attributes. The case study was performed on seven embedded systems industries (telecommunications, printing, smart manufacturing, sensors, etc.) from five countries (Greece, Netherlands, Sweden, Austria, and Finland). The results of the case study suggest that: (a) maintainability is more seriously considered when the expected lifetime of components is larger than ten years, (b) the most frequent types of debt are test, architectural, and code debt, and (c) in embedded systems the run-time qualities are prioritized compared to design-time qualities that are usually associated with TD. The obtained results can be useful for both researchers and practitioners: the former can focus their research on the most industrially-relevant aspects of TD, whereas the latter can be informed about the most common types of TD and how to focus their TDM processes

The relation relation between technical debt and corrective maintenance in PHP web applications

Context: Technical Debt Management (TDM) refers to activities that are performed to prevent the accumulation of Technical Debt (TD) in software. The state-of-research on TDM lacks empirical evidence on the relationship between the amount of TD in a software module and the interest that it accumulates. Considering the fact that in the last years, a large portion of software applications are deployed in the web, we focus this study on PHP applications. Objective: Although the relation between debt amount and interest is well-defined in traditional economics (i.e., interest is proportional to the amount of debt), this relation has not yet been explored in the context of TD. To this end, the aim of this study is to investigate the relation between the amount of TD and the interest that has to be paid during corrective maintenance. Method: To explore this relation, we performed a case study on 10 open source PHP projects. The obtained data have been analyzed to assess the relation between the amount of TD and two aspects of interest: (a) corrective maintenance (i.e., bug fixing) frequency, which translates to interest probability and (b) corrective maintenance effort which is related to interest amount. Results: Both interest probability and interest amount are positively related with the amount of TD accumulated in a specific module. Moreover, the amount of TD is able to discriminate modules that are in need of heavy corrective maintenance. Conclusions: The results of the study confirm the cornerstone of TD research, which suggests that modules with a higher level of incurred TD, are costlier in maintenance activities. In particular, such modules prove to be more defect-prone and consequently require more (corrective) maintenance effort. (C) 2017 Elsevier B.V. All rights reserved