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We give a significantly simplified proof of the exponential separation between regular and general resolution of Alekhnovich et al. (2007) as a consequence of a general theorem lifting proof depth to regular proof length in resolution. This simpler proof then allows us to strengthen the separation further, and to construct families of theoretically very easy benchmarks that are surprisingly hard for SAT solvers in practice.
Vinyals, M., Elffers, J., Johannsen, J., & Nordström, J. (2020). Simplified and Improved Separations Between Regular and General Resolution by Lifting. In Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) (Vol. 12178 LNCS, pp. 182–200). Springer. https://doi.org/10.1007/978-3-030-51825-7_14