On proper splinters in positive characteristic

Johannes Krah, Charles Vial
Mathematics, Algebraic Geometry, Algebraic Geometry (math.AG)
2023-09-04 16:00:00
While the splinter property is a local property for Noetherian schemes in characteristic zero, Bhatt observed that it imposes strong conditions on the global geometry of proper schemes in positive characteristic. We show that if a proper scheme over a field of positive characteristic is a splinter, then its Nori fundamental group is trivial and its Kodaira dimension is negative. In another direction, Bhatt also showed that any splinter in positive characteristic is a derived splinter. We ask whether the splinter property is a derived-invariant for smooth projective varieties in positive characteristic and give a positive answer for varieties with big anticanonical divisor. For that purpose, we introduce the notion of O-equivalence and show that the derived splinter property for pseudo-rational excellent schemes of finite type and separated over a fixed Noetherian base is preserved under O-equivalence. Finally, we show that global F-regularity is a derived-invariant for smooth projective varieties in positive characteristic.
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