Orlov spectra: Bounds and gaps

Matthew Ballard, David Favero, Ludmil Katzarkov

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


The Orlov spectrum is a new invariant of a triangulated category. It was introduced by D. Orlov, building on work of A. Bondal-M. Van den Bergh and R. Rouquier. The supremum of the Orlov spectrum of a triangulated category is called the ultimate dimension. In this work, we study Orlov spectra of triangulated categories arising in mirror symmetry. We introduce the notion of gaps and outline their geometric significance. We provide the first large class of examples where the ultimate dimension is finite: categories of singularities associated to isolated hypersurface singularities. Similarly, given any nonzero object in the bounded derived category of coherent sheaves on a smooth Calabi-Yau hypersurface, we produce a generator, by closing the object under a certain monodromy action, and uniformly bound this generator's generation time. In addition, we provide new upper bounds on the generation times of exceptional collections and connect generation time to braid group actions to provide a lower bound on the ultimate dimension of the derived Fukaya category of a symplectic surface of genus greater than one.

Original languageEnglish (US)
Pages (from-to)359-430
Number of pages72
JournalInventiones Mathematicae
Issue number2
StatePublished - Aug 2012
Externally publishedYes

ASJC Scopus subject areas

  • Mathematics(all)


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