Andreas Krebs, Oleg Verbitsky. Universal Covers, Color Refinement, and Two-Variable Counting Logic: Lower Bounds for the Depth. In 30th Annual ACM/IEEE Symposium on Logic in Computer Science, LICS 2015, Kyoto, Japan, July 6-10, 2015. pages 689-700, IEEE, 2015. [doi]
Abstract is missing.