Abstract:
I will consider a weakly localising Serre subcategory B in an abelian
category A, i.e. a Serre subcategory such that the quotient A/B admits
a torsion pair with the torsion-free part equivalent to the category E
of B-closed objects. I will give sufficient conditions for B to be
weakly localising in terms of torsion-tilting chains in A. I will
also argue that T-consistent pairs of t-structures of amplitude 2 are
equivalent to (strongly) torsion-tilting chains.
Given a scheme X of dimension n, the derived category D(X) admits a
T-consistent pair of t-structures of amplitude n which yields a pair
of amplitude 2. As a result, the category Coh2(X) of sheaves
supported in codimension 2 is weakly localising. I will prove that,
under additional assumptions on X, the additive category E2(X) of
locally Coh2(X)-closed objects allows us to reconstruct X up to an
isomorphism outside of codimension 2.
For a normal surface X I will construct its final model X′ from the
additive category E2(X). I will argue that X admits an open embedding
into X′ with complement of codimension two and I will give conditions
under which X is isomorphic to X′.
This is based on a joint work with A. Bondal.