Influential factors of aligning Spotify squads in mission-critical and offshore projects – a longitudinal embedded case study

Changing the development process of an organization is one of the toughest and riskiest decisions. This is particularly true if the known experiences and practices of the new considered ways of working are relative and subject to contextual assumptions. Spotify engineering culture is deemed as a new agile software development method which increasingly attracts large-scale organizations. The method relies on several small cross-functional self-organized teams (i.e., squads). The squad autonomy is a key driver in Spotify method, where a squad decides what to do and how to do it. To enable effective squad autonomy, each squad shall be aligned with a mission, strategy, short-term goals and other squads. Since a little known about Spotify method, there is a need to answer the question of: How can organizations work out and maintain the alignment to enable loosely coupled and tightly aligned squads? In this paper, we identify factors to support the alignment that is actually performed in practice but have never been discussed before in terms of Spotify method. We also present Spotify Tailoring by highlighting the modified and newly introduced processes to the method. Our work is based on a longitudinal embedded case study which was conducted in a real-world large-scale offshore software intensive organization that maintains mission-critical systems. According to the confidentiality agreement by the organization in question, we are not allowed to reveal a detailed description of the features of the explored project

Historical roots of Agile methods: where did “Agile thinking” come from?

The appearance of Agile methods has been the most noticeable change to software process thinking in the last fifteen years [16], but in fact many of the “Agile ideas” have been around since 70’s or even before. Many studies and reviews have been conducted about Agile methods which ascribe their emergence as a reaction against traditional methods. In this paper, we argue that although Agile methods are new as a whole, they have strong roots in the history of software engineering. In addition to the iterative and incremental approaches that have been in use since 1957 [21], people who criticised the traditional methods suggested alternative approaches which were actually Agile ideas such as the response to change, customer involvement, and working software over documentation. The authors of this paper believe that education about the history of Agile thinking will help to develop better understanding as well as promoting the use of Agile methods. We therefore present and discuss the reasons behind the development and introduction of Agile methods, as a reaction to traditional methods, as a result of people's experience, and in particular focusing on reusing ideas from histor

Chromatic number, clique subdivisions, and the conjectures of Haj\'os and Erd\H{o}s-Fajtlowicz

For a graph $G$, let $\chi(G)$ denote its chromatic number and $\sigma(G)$ denote the order of the largest clique subdivision in $G$. Let H(n) be the maximum of $\chi(G)/\sigma(G)$ over all $n$-vertex graphs $G$. A famous conjecture of Haj\'os from 1961 states that $\sigma(G) \geq \chi(G)$ for every graph $G$. That is, $H(n) \leq 1$ for all positive integers $n$. This conjecture was disproved by Catlin in 1979. Erd\H{o}s and Fajtlowicz further showed by considering a random graph that $H(n) \geq cn^{1/2}/\log n$ for some absolute constant $c>0$. In 1981 they conjectured that this bound is tight up to a constant factor in that there is some absolute constant $C$ such that $\chi(G)/\sigma(G) \leq Cn^{1/2}/\log n$ for all $n$-vertex graphs $G$. In this paper we prove the Erd\H{o}s-Fajtlowicz conjecture. The main ingredient in our proof, which might be of independent interest, is an estimate on the order of the largest clique subdivision which one can find in every graph on $n$ vertices with independence number $\alpha$.Comment: 14 page

Self-similar disk packings as model spatial scale-free networks

The network of contacts in space-filling disk packings, such as the Apollonian packing, are examined. These networks provide an interesting example of spatial scale-free networks, where the topology reflects the broad distribution of disk areas. A wide variety of topological and spatial properties of these systems are characterized. Their potential as models for networks of connected minima on energy landscapes is discussed.Comment: 13 pages, 12 figures; some bugs fixed and further discussion of higher-dimensional packing

An Exercise in Reverse Engineering for Safety-Critical Systems: An Experience for the Classroom

Since the Y2K crisis, reverse engineering has become a major area of work in industrial software application development, but lacks emphasis in US academia. This issue is exemplified by the high demand for software systems in new and expanding software application areas, which has resulted in systems being implemented before the requirements and design phases have been completed. Towards the maintenance of such systems, it is necessary to conducted reverse engineering for the derivation of software documentation for requirements and high-level and low-level design. When this scenario exists in the domain of safety-critical system, particularly in the aviation industry, reverse engineering takes on greater value because such software systems have to undergo development regulations and certification restrictions. This work reports on the pedagogical revelations gained from conducting reverse engineering on a software system that was developed and deployed for use in managing the assignment of commercial aircrafts to airport terminal gates. The software system incorporated genetic algorithms solutions and was implemented on a high-speed multi-processor system. The reverse engineering methodology applied was based on the RTCA DO-178C Software Considerations in Airborne Systems and Equipment Certification specification for onboard avionic software systems

In search of the origins and enduring impact of agile software development

The Agile Manifesto is a philosophical touchpoint for all agile software development (ASD) methods. We examine the manifesto and some of its associated agile methods in an effort to identify the major impacts of ASD. We have encountered some difficulty in delineating agile and non-agile software processes, which is partially the result of terminological confusion. It is clear from the volume of published research that ASD has made a significant contribution, and we have identified two lasting and important impacts. Firstly, the reduction in iteration durations and secondly, the push for reduced levels of documentation (especially in relation to software requirements). Other aspects of the Agile Manifesto may not have exerted a significant impact; for example, the use of tooling to automate processes has become central to continuous software engineering (CSE) and may not be wholly congruent with the manifesto. Furthermore, many organisations may still rely on business contracts despite calls in the manifesto for greater levels of informal customer collaboration

Bounding Helly numbers via Betti numbers

We show that very weak topological assumptions are enough to ensure the existence of a Helly-type theorem. More precisely, we show that for any non-negative integers $b$ and $d$ there exists an integer $h(b,d)$ such that the following holds. If $\mathcal F$ is a finite family of subsets of $\mathbb R^d$ such that $\tilde\beta_i\left(\bigcap\mathcal G\right) \le b$ for any $\mathcal G \subsetneq \mathcal F$ and every $0 \le i \le \lceil d/2 \rceil-1$ then $\mathcal F$ has Helly number at most $h(b,d)$. Here $\tilde\beta_i$ denotes the reduced $\mathbb Z_2$-Betti numbers (with singular homology). These topological conditions are sharp: not controlling any of these $\lceil d/2 \rceil$ first Betti numbers allow for families with unbounded Helly number. Our proofs combine homological non-embeddability results with a Ramsey-based approach to build, given an arbitrary simplicial complex $K$, some well-behaved chain map $C_*(K) \to C_*(\mathbb R^d)$.Comment: 29 pages, 8 figure

A mobile-based solution for supporting end-users in the composition of services

The final publication is available at Springer via http://dx.doi.org/10.1007/s11042-016-3910-4Currently, technologies and applications evolve to create eco-systems made up of a myriad of heterogeneous and distributed services that are accessible anytime and anywhere. Even though these services can be used individually, it is their coordinated and combined usage what provide an added value to end-users. In addition, user¿s wide adoption of mobile devices for daily activities have fostered a shift in the role played by end-users towards Internet data and services. However, existing solutions to service composition are not targeted to ordinary end-users. More easy-to-use tools have to be offered to end-users to make sure that they are successfully accepted and used by them. To this end, the work presented in this paper supports end-users in the creation of service compositions by using mobile devices. We present a Domain Specific Visual Language (DSVL) for end-users that allows them to create service compositions. A tool specifically designed for mobile devices supports this DSVL.This work has been developed with the support of MINECO under the project SMART ADAPT TIN2013-42981-P and co-financed with ERDF.Valderas Aranda, PJ.; Torres Bosch, MV.; Mansanet Benavent, I.; Pelechano Ferragud, V. (2016). A mobile-based solution for supporting end-users in the composition of services. Multimedia Tools and Applications. 1-31. https://doi.org/10.1007/s11042-016-3910-4S131Athreya B, Bahmani F, Diede A, Scaffidi C (2012) End-user programmers on the loose: a study of programming on the phone for the phone. In IEEE Symposium on Visual Languages and Human-Centric Computing (VL/HCC), Innsbruck, Austria, pp. 75–82Atoma (2015) Atoomam, a touch of magic. Accesible at: https://www.atooma.com/ . Last time accessed: December 2015Ayora C, Torres V, Weber B, Reichert M, Pelechano V (2013) Enhancing modeling and change support for process families through change patterns. In: Enterprise, business-process and information systems modeling. Springer, Berlin, pp. 246–260Boehm B, Abts C, Brown A, Chulani S, Clark B, Horowitz E, Madchy R, Reifer D, Steece B (2000) Software Cost Estimation with COCOMOII. Upper Saddle River: Prentice HallBPDM (2014) Business Process Defintion Metamodel, volume ii: Process Definitions. http://www.omg.org/spec/BPDM/1.0/volume2/PDFCasati F (1998) Models, semantics, and formal methods for the design of workflows and their exceptions. PhD thesis, MilanoCouper MP, Tourangeau R, Conrad FG, Crawford SD (2004) What they see is what we get: response options for web surveys. Soc Sci Comput Rev 22(1):111–127Cuccurullo S, Francese R, Risi M, Tortora G (2011) MicroApps development on mobile phones. In: End-user development. Springer, Berlin, pp. 289–294Dadam P, Reichert M (2009) The ADEPT project: a decade of research and development for robust and flexible process support. Comput Sci - R&D 23:81–97Danado J, Paternò F (2014) Puzzle: a mobile application development environment using a jigsaw metaphor. J Vis Lang Comput 25(4):297–315Danado J, Davies M, Ricca P, Fensel A (2010) An authoring tool for user generated mobile services. In: Future internet-FIS 2010. Springer, Berlin, pp. 118–127Dey AK, Sohn T, Streng S, Kodama J (2006) iCAP: interactive prototyping of context-aware applications. In: Pervasive computing. Springer, Berlin, pp. 254–271Engeström Y, Miettinen R, Punamäki RL (1999) Perspectives on activity theory. Cambridge University Press, CambridgeGalitz WO (2002) The essential guide to user interface design: an introduction to GUI. In: Design principles and techniques. Wiley, New YorkGil M, Serral E, Valderas P, Pelechano V (2013) Designing for user attention: a method for supporting unobtrusive routine tasks. Sci Comput Program 78(10):1987–2008Gubbi J, Buyya R, Marusic S, Palaniswami M (2013) Internet of things (IoT): a vision, architectural elements, and future directions. Futur Gener Comput Syst 29(7):1645–1660Haines W, Gervasio M, Spaulding A, Peintner B (2010) Recommendations for end-user development. In ACM Workshop on User-Centric Evaluation of Recommender Systems and their Interfaces, Barcelona, Spain, pp. 42-49Häkkilä J, Korpipää P, Ronkainen S, Tuomela U (2005) Interaction and end-user programming with a context-aware mobile application. In: Human-computer interaction-INTERACT 2005. Springer, Berlin, pp. 927–937ICIS (2015) Internet Computing in the Internet of Services. Summer School. Department of Informatics Engineering of the University of Coimbra. Available at: http://icis.uc.pt/ . Last time accessed: December 2015Ifttt (2015) Ifttt, If This Then That. Accesible at: https://ifttt.com/ . Last time accessed: December 2015Larman C, Basili VR (2003) Iterative and incremental development: a brief history. Computer 6:47–56Lewis JR (1995) IBM computer usability satisfaction questionnaires: psychometric evaluation and instructions for use. Int J Hum Comput Interact 7(1):57–78Liberman H, Paternò F, Klann M, Wulf V (2006) End user development. In: Liberman H, Paternò F, Wulf V (eds) End-user development: an emerging paradigm, vol 9, pp. 427–457Locale (2015) Accesible at: http://www.twofortyfouram.com . Last time accessed: December 2015Lucci G, Paternò F (2014) Understanding end-user development of context-dependent applications in smartphones. In: Human-centered software engineering. Springer, Berlin, pp. 182–198Mansanet I, Torres V, Valderas P, Pelechano V (2014) A Mobile End-Use Tool for service Compositions. X Jornadas de Ciencia e Ingeniería de Servicios (JCIS 2014), 25–35Mansanet I, Torres V, Valderas P, Pelechano V (2015) IoT Compositions by and for the Crowd. XI Jornadas de Ciencia e Ingeniería de Servicios (JCIS 2015)Neil T (2014) Mobile design pattern gallery: UI patterns for smartphone apps. “O’Reilly Media, Inc.”, SebastopolNielsen J (2005) Ten usability heuristics. https://www.nngroup.com/articles/ten-usability-heuristics . Last time accessed: February 2016Renger M, Kolfschoten GL, de Vreede GJ (2008) Challenges in collaborative modeling: A literature review. In Advances in enterprise engineering I, held at CAiSE 2008, Montpellier, 10. 61–77Repenning A, Ioannidou A (2006) What makes end-user development tick? 13 design guidelines. End user development, Human-Computer Interaction Series, vol 9, pp. 51–85Runeson P, Höst M (2009) Guidelines for conducting and reporting case study research in software engineering. Empir Softw Eng 14(2):131–164Segal J (2005) Two principles of end-user software engineering research, In ACM SIGSOFT software engineering notes (Vol. 30, No. 4, pp. 1–5). ACM, New YorkSerral E, Valderas P, Pelechano V (2013) Context-adaptive coordination of pervasive services by interpreting models during runtime†. Comput J 56(1):87–114Tasker (2015) Tasker, Total Automation for Android. Accesible at: http://tasker.dinglisch.net/ . Last time accessed: December 2015.Uden L, Valderas P, Pastor O (2008) An activity-theory-based model to analyse Web application requirements. Inf Res 13(2):1Valderas P, Pelechano V, Pastor O (2006) A transformational approach to produce web application prototypes from a web requirements model. Int J Web Eng Technol 3(1):4–42Van Deursen A, Klint P, Visser J (2000) Domain-specific languages: an annotated bibliography. Sigplan Notices 35(6):26–36Van Welie M, Trætteberg H (2000) Interaction patterns in user interfaces. In 7th. Pattern Languages of Programs Conference (pp. 13–16)Weber B, Reichert M, Rinderle S (2008) Change patterns and change support features - enhancing flexibility in process-aware information systems. Data Knowl Eng 66:438–466Yu J, Sheng QZ, Han J, Wu Y, Liu C (2012) A semantically enhanced service repository for user-centric service discovery and management. Data Knowl Eng 72:202–21

An update on the Hirsch conjecture

The Hirsch conjecture was posed in 1957 in a letter from Warren M. Hirsch to George Dantzig. It states that the graph of a d-dimensional polytope with n facets cannot have diameter greater than n - d. Despite being one of the most fundamental, basic and old problems in polytope theory, what we know is quite scarce. Most notably, no polynomial upper bound is known for the diameters that are conjectured to be linear. In contrast, very few polytopes are known where the bound $n-d$ is attained. This paper collects known results and remarks both on the positive and on the negative side of the conjecture. Some proofs are included, but only those that we hope are accessible to a general mathematical audience without introducing too many technicalities.Comment: 28 pages, 6 figures. Many proofs have been taken out from version 2 and put into the appendix arXiv:0912.423