期刊名称：Electronic Colloquium on Computational Complexity
印刷版ISSN：1433-8092
出版年度：2021
卷号：21
语种：English
出版社：Universität Trier, Lehrstuhl für Theoretische Computer-Forschung
摘要：This paper surveys the development of propositional proof complexity and the seminal contributions of Alasdair Urquhart. We focus on the central role of counting principles, and in particular Tseitin's graph tautologies, to most of the key advances in lower bounds in proof complexity. We reflect on a couple of key ideas that Urquhart pioneered: (i) graph expansion as a tool for distinguishing between easy and hard principles, and (ii) ``reductive" lower bound arguments, proving via a simulation theorem that an optimal proof cannot bypass the obvious (inefficient) one.
