Some recent conference talks by Ross Willard

• The Constraint Satisfaction Problem: Complexity and Approximability (Schloss Dagstuhl Seminar 09441, 2009), "∃-InvSat (a.k.a. pp-definability) is co-NExpTime-complete," slides (pdf) (164 KB).
• Summer School on Algebra and Ordered Sets (Trest, Czech Republic, 2008), "Universal Algebra and Computational Complexity," a tutorial: slides 1 (pdf) (292 KB); slides 2 (pdf) (308 KB); slides 3 (pdf) (352 KB).
• Workshop on Universal Algebra and the Constraint Satisfaction Problem (Nashville, 2007), "Quick course in universal algebra and tame congruence theory," slides (pdf) (232 KB).
• Order, Algebra, and Logics (Nashville, 2007), "Four unsolved problems in congruence permutable varieties," slides (pdf) (188 KB).
• Logic Colloquium 2004 (Torino) tutorial, "An overview of modern universal algebra," paper (pdf) (244 KB).