Publications and Preprints
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Descent and generation for noncommutative coherent algebras over schemes (with P. Lank and K. Manali Rahul), 2024.
arXiv |
▸ Abstract
▸ Our work investigates a form of descent, in the fppf and h topologies, for generation of triangulated categories obtained from noncommutative coherent algebras over schemes.
In addition, also the behaviour of generation with respect to the derived pushforward of proper morphisms is studied.
This allows us to exhibit many new examples where the associated bounded derived categories of coherent sheaves admit strong generators.
We achieve our main results by combining Matthew's concept of descendability with Stevenson's tensor actions on triangulated categories, allowing us to generalize statements regarding generation into the noncommutative setting.
In particular, we establish a noncommutative generalization of Aoki's result to Azumaya algebras over quasi-excellent schemes.
Moreover, as a byproduct of the tensor action, we extend Olander's result on countable Rouquier dimension to the noncommutative setting for Azumaya algebras over derived splinters,
and we extend a result of Ballard-Iyengar-Lank-Mukhopadhyay-Pollitz regarding strong generation for schemes of prime characteristic to the case of Azumaya algebras.
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Approximability and Rouquier dimension for noncommuative algebras over schemes (with P. Lank and K. Manali Rahul), 2024.
arXiv |
▸ Abstract
▸ This work is concerned with approximability (à la Neeman) and Rouquier dimension for triangulated categories associated to noncommutative algebras over schemes.
Amongst other things, we establish that the category of perfect complexes of a Noetherian quasi-coherent algebra over a separated Noetherian scheme is strongly generated if, and only if,
there exists an affine open cover where the algebra has finite global dimension.
As a consequence, we solve an open problem posed by Neeman.
Further, as a first application, we study the existence of generators for Azumaya algebras.
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Categorical resolutions of filtered schemes, J. Noncommut. Geom., 2024.
arXiv |
Journal |
▸ Abstract
▸ We give an alternative proof of the theorem by Kuznetsov and Lunts, stating that any separated scheme of finite type over a field of characteristic zero admits a categorical resolution of singularities.
Their construction makes use of the fact that every variety (over a field of characteristic zero) can be resolved by a finite sequence of blow-ups along smooth centres.
We merely require the existence of (projective) resolutions.
To accomplish this we put the $\mathcal{A}$-spaces of Kuznetsov and Lunts in a different light, viewing them instead as schemes endowed with finite filtrations.
The categorical resolution is then constructed by gluing together differential graded categories obtained from a hypercube of finite length filtered schemes.
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A note on affine cones over Grassmannians and their stringy $E$-functions, Proc. Amer. Math. Soc., 2023.
arXiv |
Journal |
▸ Abstract
▸ We compute the stringy $E$-function of the affine cone over a Grassmannian.
If the Grassmannian is not a projective space then its cone does not admit a crepant resolution.
Nonetheless the stringy $E$-function is sometimes a polynomial and in those cases the cone admits a noncommutative crepant resolution.
This raises the question as to whether the existence of a noncommutative crepant resolution implies that the stringy $E$-function is a polynomial.