Problems / geometry-topology
geometry-topology / Birational geometry; minimal model program
Existence of minimal models and Mori fibre spaces for projective log canonical pairs, in generalized-pair form
Theorem 1.1: for a projective generalized lc Q-pair (X,B+M) over an algebraically closed field of characteristic zero there is a birational map X⇢Y extracting no divisors, with (Y,BY+MY) generalized lc and log discrepancies not decreasing (strictly on contracted divisors), such that KY+BY+MY is nef if KX+B+M is pseudo-effective, and otherwise Y has a Mori fibre space structure with relative Picard number one. With M=0 this gives the ordinary lc case. Companion: smooth projective varieties with κσ(KX)=1 have Q-factorial terminal minimal models. Not shown: termination of arbitrary flip sequences, real coefficients, abundance (claimed in a separate release paper), or Q-factorial models in general.