The concept of extension-based proofs models the idea of a valency argument which is widely used in distributed computing. Extension-based proofs have been shown to be limited in power: there is no extension-based proof of the impossibility of a wait-free protocol for (n,k)-set agreement among n > k ≥ 2 processes. Previous work used a restricted class of reductions to show that there are no extension-based proofs of the impossibility of wait-free protocols for some other distributed computing problems. It is known that for a restricted class of reductions, if a task 𝒯 reduces to 𝒮 and 𝒯 has an augmented extension-based proof that it is impossible to solve in the NIS model, then so does 𝒮. We introduce multiple-instance extension-based proofs and show that, if 𝒯 reduces to multiple instances of 𝒮, instead of just one instance and 𝒯 has an augmented extension-based proof, then 𝒮 has a multiple-instance extension-based proof that it is impossible to solve in the NIIS model. We introduce a new version of extension-based proofs that can further our understanding of extension-based proofs and their limitations.
@InProceedings{shi_et_al:LIPIcs.OPODIS.2024.19, author = {Shi, Yusong and Liu, Weidong}, title = {{A General Class of Reductions and Extension-Based Proofs}}, booktitle = {28th International Conference on Principles of Distributed Systems (OPODIS 2024)}, pages = {19:1--19:17}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-360-7}, ISSN = {1868-8969}, year = {2025}, volume = {324}, editor = {Bonomi, Silvia and Galletta, Letterio and Rivi\`{e}re, Etienne and Schiavoni, Valerio}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.OPODIS.2024.19}, URN = {urn:nbn:de:0030-drops-225559}, doi = {10.4230/LIPIcs.OPODIS.2024.19}, annote = {Keywords: Reductions, Impossibility proofs, Extension-based proof} }
Feedback for Dagstuhl Publishing