The papers in this special issue represent some of the best submissions to the 23rd Symposium onFormalMethods (FM2019),whichwas part of the 3rdWorldCongress onFormalMethods held in Porto, Portugal in 2019. The World Congress is an event occurring every 10 years, and attracts scientists from all over the world to celebrate and exchange ideas on the technical advances made and realworld experiences of the formal analysis of systems applied across a diversity of applications. The 3rd World Congress was both an optimistic look into “The Next 30 Years” as well as an opportunity to reflect on the 30 years since the first VDM symposium on the Vienna Development Method for formal software development in 1987 brought together researchers with the common goal of creating methods to produce high quality software based on rigour and reason. FM 2019 attracted 129 submissions, out of which 39 were accepted for presentation. A total of 18 papers were selected to be significantly extended to journal-length papers; nine of the selections appear here and the remaining nine appear in a parallel special issue published in Formal Aspects of Computing. All papers underwent a thorough review process, requiring two to three rounds of revision. We briefly describe the contents of the nine papers that together constitute this special issue. The paper Pegasus: Sound Continuous Invariant Generation, by Andrew Sogokon, Stefan Mitsch,YongKiamTan,KatherineCordwell andAndré Platzer, introduces Pegasus, a tool for automatic generation or synthesis of continuous invariants for hybrid systems, which serves the verification of safety properties of such systems. The tool is implemented inMathematica and its interface is accessible through Mathematica and the KeYmaera X theorem prover. A prominent feature is that it allows to combine several well-known invariant generation methods, according to a differential saturation strategy, which can be partly customised via a set of configuration parameters. In addition, by integration within a theorem prover, the tool

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形式化方法：实际应用和基础

本期特刊中的论文代表了向第 23 届形式方法研讨会 (FM2019) 提交的最佳论文，该研讨会是 2019 年在葡萄牙波尔图举行的第三届世界形式方法大会的一部分。世界大会每 10 年举行一次，吸引了来自世界各地的科学家在世界各地庆祝和交流关于在各种应用程序中应用的系统的正式分析所取得的技术进步和实际经验的想法。第三届世界大会既是对“未来 30 年”的乐观展望，也是反思自 1987 年第一次关于正式软件开发的维也纳开发方法的 VDM 研讨会将具有共同目标的研究人员聚集在一起以来的 30 年的机会创建基于严谨和理性的高质量软件的方法。FM 2019 吸引了 129 份提交，其中 39 份被接受展示。共有18篇论文被选为显着扩展为期刊长度的论文；其中九个选集出现在此处，其余九个出现在《计算的正式方面》上发表的平行特刊中。所有论文都经过了彻底的审查过程，需要两到三轮修改。我们简要介绍了构成本期特刊的九篇论文的内容。论文 Pegasus: Sound Continuous Invariant Generation 由 Andrew Sogokon、Stefan Mitsch、YongKiamTan、KatherineCordwell 和 André Platzer 撰写，介绍了 Pegasus，一种用于自动生成或合成混合系统连续不变量的工具，用于验证此类系统的安全特性。该工具在 Mathematica 中实现，其界面可通过 Mathematica 和 KeYmaera X 定理证明器访问。一个突出的特点是它允许根据差分饱和策略组合几种众所周知的不变量生成方法，可以通过一组配置参数进行部分定制。此外，通过在定理证明器中集成，该工具