ETAPS2008wasthe11thinstanceoftheEuropeanJointConferencesonTheory and Practice of Software. ETAPS is an annual federated conference that was established in 1998 by combining a number of existing and new conferences. This yearit comprised?ve conferences (CC, ESOP,FASE, FOSSACS, TACAS), 22satelliteworkshops(ACCAT,AVIS,Bytecode,CMCS,COCV,DCC,FESCA, FIT, FORMED, GaLoP, GT-VMT, LDTA, MBT, MOMPES, PDMC, QAPL, RV,SafeCert,SC,SLA++P,WGT,andWRLA),ninetutorials,andseveninvited lectures (excluding those that were speci?c to the satellite events). The ?ve main conferences received 571 submissions, 147 of which were accepted, giving an overall acceptance rate of less than 26%, with each conference below 27%. Congratulationsthereforetoallthe authorswhomadeittothe ?nalprogramme! I hope that most of the other authors will still have found a way of participating in this exciting event, and that you will all continue submitting to ETAPS and contributing to make of it the best conference in the area. The events that comprise ETAPS address various aspects of the system - velopment process, including speci?cation, design, implementation, analysis and improvement. The languages, methodologies and tools which support these - tivities are all well within its scope. Di?erent blends of theory and practice are represented, with an inclination towards theory with a practical motivation on the one hand and soundly based practice on the other. Many of the issues involved in software design apply to systems in general, including hardware s- tems, and the emphasis on software is not intended to be exclusive.

This book constitutes the refereed proceedings of the 20th Brazilian Symposium on Formal Methods, SBMF 2017, which took place in Recifel, Brazil, in November/December 2017.The 16 papers presented together with three invited talks were carefully reviewed and selected from 37 submissions. They are organized in the following topical sections: formal methods integration and experience reports; model checking; refinement and verification; and semantics and languages. The chapter 'Rapidly Adjustable Non-Intrusive Online Monitoring for Multi-core Systems' is published open access under a CC BY 4.0 license.