We show confluence of a conditional term rewriting system CL-pc^1, which is an extension of Combinatory Logic by Boolean constants. This solves problem 15 from the RTA list of open problems. The proof has been fully formalized in the Coq proof assistant.
@InProceedings{czajka:LIPIcs.FSCD.2017.14, author = {Czajka, Lukasz}, title = {{Confluence of an Extension of Combinatory Logic by Boolean Constants}}, booktitle = {2nd International Conference on Formal Structures for Computation and Deduction (FSCD 2017)}, pages = {14:1--14:16}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-047-7}, ISSN = {1868-8969}, year = {2017}, volume = {84}, editor = {Miller, Dale}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FSCD.2017.14}, URN = {urn:nbn:de:0030-drops-77368}, doi = {10.4230/LIPIcs.FSCD.2017.14}, annote = {Keywords: combinatory logic, conditional linearization, unique normal form property, confluence} }
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