Quasicoherent sheaves on complex noncommutative two-tori

Abstract

We introduce the notion of a quasicoherent sheaf on a complex noncommutative two-torus T as an ind-object in the category of holomorphic vector bundles on T. Extending the results of [10] and [9] we prove that the derived category of quasicoherent sheaves on T is equivalent to the derived category of usual quasicoherent sheaves on the corresponding elliptic curve. We define the rank of a quasicoherent sheaf on T that can take arbitrary nonnegative real values. We study the category Qcoh(nT) obtained by taking the quotient of the category of quasicoherent sheaves by the subcategory of objects of rank zero (called torsion sheaves). We show that projective objects of finite rank in Qcoh(nT) are classified up to an isomorphism by their rank. We also prove that the subcategory of objects of finite rank in Qcoh(nT) is equivalent to the category of finitely presented modules over a semihereditary algebra.