Proof Complexity Generators ======================= We shall discuss in detail the current search for tautologies that have no short proofs even in strong propositional proof systems like Extended-Frege. The particular tautologies we shall discuss are obtained from any polynomial map g (more exactly, from P/poly map g); they express that a string is not in the range of g. The ultimate goal is to deduce the hardness of these formulas for at least Extended-Frege from some general, plausible computational hardness hypothesis (a family of tautologies is said to be "hard for a proof system P" if the tautologies in the family have no polynomial-size proofs). This talk mainly follows Jan Krajicek's paper: "Dual weak pigeonhole principle, pseudo-surjective functions, and provability of circuit lower bounds", Journal of Symbolic Logic, 69(1), pp. 265