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derived algebra

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derived algebra
Namederived algebra
FieldMathematics
SubfieldAlgebra, Homological Algebra, Category Theory
Introduced20th century
ContributorsJean-Pierre Serre; Alexander Grothendieck; John Milnor; Daniel Quillen; Pierre Deligne; Maxim Kontsevich; Vladimir Drinfeld; Jacob Lurie; Henri Cartan; Jean-Louis Verdier

derived algebra

Derived algebra is the study of algebraic objects and their morphisms enriched by homological and higher-categorical structures, extending classical Emmy Noether-style algebraic methods with tools from Homological algebra, Category theory, and Algebraic topology. It unifies constructions from Jean-Pierre Serre-cohomology, Alexander Grothendieck-style derived functors, and Quillen-model categories to treat extensions, deformations, and higher homotopy coherences within algebraic settings such as commutative rings, associative algebras, and Lie algebras.

Definition and basic concepts

Derived algebra centers on derived objects such as complexes of modules, differential graded algebras, and spectra studied up to quasi-isomorphism or weak equivalence; core notions include homotopy category, derived functor, and Ext and Tor groups. Key constructions employ chain complexes, cochain complexes, and model structures from Daniel Quillen to form derived categories à la Jean-Louis Verdier and triangulated structures seen in Bernhard Neumann-adjacent developments. Homotopical notions such as homotopy limit, homotopy colimit, and spectral sequence tools like the Adams spectral sequence are fundamental for calculations and invariants. The subject interacts with concepts introduced by Henri Cartan and formalized through techniques used by John Milnor in algebraic topology.

Historical development and motivation

Motivation arose from problems in Alexander Grothendieck's school addressing derived functors in sheaf cohomology and from homotopical methods in Algebraic topology used by Samuel Eilenberg and Saunders Mac Lane. The formal notion of derived category was introduced by Jean-Louis Verdier in the context of the Grothendieck school and later expanded by Pierre Deligne for applications to Hodge theory and Weil conjectures. Daniel Quillen developed model category theory to axiomatize homotopy-theoretic algebraic methods, while Maxim Kontsevich and Vladimir Drinfeld brought derived techniques into deformation quantization and quantum groups. Recent categorical foundations were significantly advanced by Jacob Lurie in the framework of infinity-categorys, influencing work at institutions like Institute for Advanced Study and collaborations involving Institute of Mathematics of the Russian Academy of Sciences.

Constructions and examples

Typical constructions include the derived category D(A) of an abelian category A as in Grothendieck's approach to cohomology, the derived tensor product and RHom between complexes, and differential graded algebra (DGA) models appearing in rational homotopy theory by Dennis Sullivan. Examples span the derived category of modules over a commutative ring studied in Serre's work, derived endomorphism DGAs for finite-dimensional algebras connected to Representation theory of algebras, and derived deformation complexes used by Maurice Auslander-influenced representation theorists. Further examples arise from Koszul duality contexts, Calabi–Yau categories studied by Maxim Kontsevich, and derived categories of coherent sheaves on varieties investigated by researchers at Institut des Hautes Études Scientifiques.

Homological and categorical frameworks

The homological backbone uses derived functors, long exact sequences, and spectral sequences pioneered in Jean-Pierre Serre and Henri Cartan traditions, while categorical formalisms deploy triangulated categories, DG-categories, and stable infinity-category frameworks developed by Jacob Lurie. Model category frameworks from Daniel Quillen provide homotopical control, with further elaboration via Bousfield localization and Brown representability theorem contexts. Enhanced structures include pretriangulated DG-categories by Bernhard Keller and A-infinity categories arising in Kenji Fukaya-related mirror symmetry, drawing on techniques from Paul Seidel and Mikhail Gromov-adjacent work. The interplay of Morita theory and derived Morita equivalences links to approaches used by Idun Reiten and Osamu Iyama in representation theory.

Relations to derived algebraic geometry

Derived algebra underpins derived algebraic geometry developed by Alexander Grothendieck-inspired programs and modernized by Jacob Lurie and Bertrand Toën with collaborators like Gabriele Vezzosi and Bertrand Toen. Derived algebraic geometry replaces classical algebraic objects such as schemes and stacks with derived schemes, derived stacks, and spectral schemes built from simplicial commutative rings or E-infinity rings introduced by G. W. Moore-adjacent homotopy ring theory. This framework impacts formulations of moduli problems studied by Deligne, applications to Donaldson–Thomas theory investigated by Richard Thomas and Maxim Kontsevich, and formulations of the Langlands program where derived structures appear in categorical and geometric representation-theoretic contexts pursued at institutions like Princeton University and IHES.

Applications and notable results

Applications include calculation of deformation spaces via cotangent complexes used in Illusie-related work, formulating and proving equivalences in Homological mirror symmetry conjectures advanced by Maxim Kontsevich and evidence produced by Paul Seidel and Dmitry Orlov. Derived techniques resolved problems in singularity theory and representation theory such as derived equivalences classifying blocks in modular representation theory studied by Jon F. Carlson and Jeremy Rickard. Important theorems include the existence of model structures for DG-algebras by Bernhard Keller and Vladimir Hinich, comparison results between derived categories and infinity-categorical enhancements by Jacob Lurie, and applications to arithmetic geometry via derived deformation rings used in Andrew Wiles-adjacent modularity lifting strategies. Current research links derived methods to quantum field theoretic constructions explored by Edward Witten and categorical approaches at centers like Mathematical Sciences Research Institute.

Category:Algebra