SoSyM has been growing in two important areas: an increase in annual impact factor (IF) and number of submissions. The large uptick in the number of submissions is a very healthy sign for a journal, especially when coupled with a corresponding increase in IF. However, an increase in submissions also has an interesting side effect that can hamper the ability to process accepted articles in a timely manner. Editors and publishers are challenged with estimating the future set of incoming submitted papers. Also, the perception of a journal decreases when the number of papers published per issue is observed as decreasing or near empty. Publishers must carefully balance the number of issues released per year and the overall number of pages printed to match the projected incoming submissions.

Over the past 5 years, SoSyM has only conservatively increased the number of printed papers per issue. However, the number of accepted papers (due to the concomitant submission increase) began to slowly outgrow the number of papers published per issue. Over time, that led to a rather large backlog, reducing the time that authors could claim an official printed issue (with volume and issue number, for indexing purposes) on their resume. SoSyM has always offered an online-first option for accepted papers, but many authors need to document their contributions with an official printed volume for professional evaluation or other needs that assess merit by an author’s publication record.

Because of the growing backlog of accepted papers waiting for official publication in print, the SoSyM editorial board requested a re-evaluation of our publication process with our publisher, Springer. We are very delighted to announce that SoSyM will significantly reduce the current backlog over the next few issues of 2019. Thus, this issue of SoSyM is one of the largest in the history of the journal! We expect the backlog to be reduced over the next two issues, leaving a more acceptable target of about 6 months from the time a paper is accepted to the time that it appears in an actual printed volume.

We are very grateful to the SoSyM editorial board for their helpful suggestions and to Springer (especially Ralf Gerstner) for recognition of the need to reduce the backlog.

1 Best reviewers of SoSyM 2018

In the previous issue (volume 19.1), we thanked all of the reviewers who contributed to SoSyM throughout 2018. We would like to acknowledge the “Best Reviewers” for 2018, based on the depth and completeness of comments offered in a contributed review last year. We thank all of the reviewers for their assistance in providing authors with valuable feedback and helping us in the decisions that are made for each submission. The 2018 Best SoSyM Reviewers are: Anthony Anjorin, Gabor Bergmann, Neil Ernst, Kathrin Figl, Mario Gleirscher, Paul Ralph, Manfred Reichert, Christoph Seidl, Stefan Stanciulescu, Eric Walkingshaw, and Matthias Weidlich. Each reviewer will receive a certificate of appreciation for their contributions.

2 Contents of this issue

This issue is one of the largest ever published by SoSyM, with a Theme Section, two Special Sections, and 11 Regular Papers. The contents of this issue include the following:

  1. 1.

    Theme Section on Model-Based Testing

    Guest Editors: Mike Papadakis, Shaukat Ali, and Gilles Perrouin

  2. 2.

    Special Section on ECMFA and ICMT at STAF 2016

    Guest Editors: Andrzej Wasowski and Pieter van Gorp

  3. 3.

    BPMDS 2016 Special Section

    Guest Editors: Rainer Schmidt and Ilia Bider

  4. 4.

    Regular Papers

    • “Managing design-time uncertainty” by Michalis Famelis and Marsha Chechik

    • “The next evolution of MDE: a seamless integration of machine learning into domain modeling” by Thomas Hartmann, Assaad Moawad, Francois Fouquet, and Yves Le Traon

    • “End-to-end model-transformation comprehension through fine-grained traceability information” by Victor Guana and Eleni Stroulia

    • “3LConOnt: a three-level ontology for context modelling in context-aware computing” by Oscar Cabrera, Xavier Franch, and Jordi Marco

    • “Uncertainty-Wise Cyber-Physical System test modeling” by Man Zhang, Shaukat Ali, Tao Yue, Roland Norgren, and Oscar Okariz

    • “Assessing the impact of meta-model evolution: a measure and its automotive application” by Darko Durisic, Miroslaw Staron, Matthias Tichy, and Jörgen Hansson

    • “SMTIBEA: a hybrid multi-objective optimization algorithm for configuring large constrained software product lines” by Jianmei Guo, Jia Hui Liang, Kai Shi, Dingyu Yang, Jingsong Zhang, Krzysztof Czarnecki, Vijay Ganesh, and Hui Qun Yu

    • “Formal modeling of biomedical signal acquisition systems: source of evidence for certification” by Alvaro Sobrinho, Leandro Dias da Silva, Angelo Perkusich, Paulo Cunha, Thiago Cordeiro, and Antonio Marcus Nogueira Lima

    • “Applying design patterns in the search-based optimization of software product line architectures” by Giovani Guizzo, Thelma Colanzi, and Silvia Vergilio

    • “FlexiSketch: a lightweight sketching and metamodeling approach for end-users” by Dustin Wüest, Norbert Seyff, and Martin Glinz

    • “From use case maps to executable test procedures: a scenario-based approach” by Nader Kesserwan, Rachida Dssouli, Jamal Bentahar, Bernard Stepien, and Pierre Labreche

We hope that you enjoy reading the papers in this second very large issue!

Huseyin Ergin, Jeff Gray, Bernhard Rumpe, and Martin Schindler