The strong Rickard conjecture for functor categories

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Let X\mathcal{X} and Y\mathcal{Y} be essentially small idempotent complete additive categories. Write Mod⁡−X\operatorname{Mod}-\mathcal{X} for the category of modules over X\mathcal{X}, mod⁡∞−X\operatorname{mod}_{\infty}-\mathcal{X} for its corresponding finitely presented functor category, DD and D−D^- for the derived and bounded-above derived categories, DbD^b for the bounded derived category, and Kb(X)K^b(\mathcal{X}) for the bounded homotopy category. Strong Rickard conjecture. The following conditions are equivalent:

(0)D(Mod⁡−X) and D(Mod⁡−Y) are triangle equivalent;(1)D−(Mod⁡−X) and D−(Mod⁡−Y) are triangle equivalent;(2)D−(mod⁡∞−X) and D−(mod⁡∞−Y) are triangle equivalent;(3)Db(mod⁡∞−X) and Db(mod⁡∞−Y) are triangle equivalent;(4)Kb(X) and Kb(Y) are triangle equivalent;(5)There is a tilting subcategory T of Kb(X) such that T≅Y as additive categories.\begin{array}{ll} \text{(0)} & D(\operatorname{Mod}-\mathcal{X})\text{ and }D(\operatorname{Mod}-\mathcal{Y})\text{ are triangle equivalent};\\ \text{(1)} & D^-(\operatorname{Mod}-\mathcal{X})\text{ and }D^-(\operatorname{Mod}-\mathcal{Y})\text{ are triangle equivalent};\\ \text{(2)} & D^-(\operatorname{mod}_{\infty}-\mathcal{X})\text{ and }D^-(\operatorname{mod}_{\infty}-\mathcal{Y})\text{ are triangle equivalent};\\ \text{(3)} & D^b(\operatorname{mod}_{\infty}-\mathcal{X})\text{ and }D^b(\operatorname{mod}_{\infty}-\mathcal{Y})\text{ are triangle equivalent};\\ \text{(4)} & K^b(\mathcal{X})\text{ and }K^b(\mathcal{Y})\text{ are triangle equivalent};\\ \text{(5)} & \text{There is a tilting subcategory }\mathcal{T}\text{ of }K^b(\mathcal{X})\text{ such that }\mathcal{T}\cong\mathcal{Y}\text{ as additive categories.} \end{array}

If X\mathcal{X} and Y\mathcal{Y} are not assumed to be small, conditions (2), (3), (4), and (5) are still equivalent. Moreover, every triangle equivalence in (0)--(3) restricts to a triangle equivalence as in (4). This generalizes Rickard's Morita theory from rings to functor categories; partial results are known for more general small additive categories, but the full equivalence remains unresolved.

References

Primary source

Julia Sauter, “Tilting Theory in exact categories”, arXiv:2208.06381 (2022).

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