A. David-basin, W. Fokkink, S. Merz, A. Middeldorp, T. Nipkow et al., We are grateful to the FroCoS 2017 program chairs, Clare Dixon and Marcelo Finger, and to the program committee for giving us this opportunity to present our research. We are also indebted to Andreas Abel, Daniel Wand, and Makarius Wenzel, and to dozens of anonymous reviewers (including those who rejected our manuscript " Witnessing (co)datatypes " [18] six times

P. Kun?ar and . Were, Security Type Systems and Deduction " (NI 491/13-2 and NI 491/13-3) as part of the program Reliably Secure Software Systems (RS 3 , priority program 1496) Kun?ar was also supported by the DFG project Integration der Logik HOL mit den Programmiersprachen ML und Haskell " (NI 491/10-2). Lochbihler was supported by the Swiss National Science Foundation (SNSF) grant " Formalising Computational Soundness for Protocol Implementations VOWS: Verification of Web-based Systems, Popescu was supported by the UK Engineering and Physical Sciences Research Council (EPSRC) starting grant Sternagel and Thiemann were supported by the Austrian Science Fund (FWF)

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