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\newtheorem{prop}{Proposition} \newtheorem{cor}{Corollary} \newtheorem*{utheorem}{Theorem} \newtheorem*{ulemma}{Lemma} \newtheorem*{uprop}{Proposition} \newtheorem*{ucor}{Corollary} \theoremstyle{definition} \newtheorem{defn}{Definition} \newtheorem{example}{Example} \newtheorem*{udefn}{Definition} \newtheorem*{uexample}{Example} \theoremstyle{remark} \newtheorem{remark}{Remark} \newtheorem{note}{Note} \newtheorem*{uremark}{Remark} \newtheorem*{unote}{Note} %------------------------------------------------------------------- \begin{document} %------------------------------------------------------------------- \section*{dg-category} \hypertarget{context}{}\subsubsection*{{Context}}\label{context} \hypertarget{homological_algebra}{}\paragraph*{{Homological algebra}}\label{homological_algebra} [[!include homological algebra - contents]] \hypertarget{enriched_category_theory}{}\paragraph*{{Enriched category theory}}\label{enriched_category_theory} [[!include enriched category theory contents]] \hypertarget{contents}{}\section*{{Contents}}\label{contents} \noindent\hyperlink{idea}{Idea}\dotfill \pageref*{idea} \linebreak \noindent\hyperlink{definition}{Definition}\dotfill \pageref*{definition} \linebreak \noindent\hyperlink{properties}{Properties}\dotfill \pageref*{properties} \linebreak \noindent\hyperlink{the_infinity1category_of_dgcategories}{The (infinity,1)-category of dg-categories}\dotfill \pageref*{the_infinity1category_of_dgcategories} \linebreak \noindent\hyperlink{relation_to_stable_categories}{Relation to stable $\infty$-categories}\dotfill \pageref*{relation_to_stable_categories} \linebreak \noindent\hyperlink{aspects_of_dgcategories}{Aspects of dg-categories}\dotfill \pageref*{aspects_of_dgcategories} \linebreak \noindent\hyperlink{related_concepts}{Related concepts}\dotfill \pageref*{related_concepts} \linebreak \noindent\hyperlink{references}{References}\dotfill \pageref*{references} \linebreak \noindent\hyperlink{overviews}{Overviews}\dotfill \pageref*{overviews} \linebreak \noindent\hyperlink{homotopy_theory_of_dgcategories}{Homotopy theory of dg-categories}\dotfill \pageref*{homotopy_theory_of_dgcategories} \linebreak \noindent\hyperlink{derived_noncommutative_geometry}{Derived noncommutative geometry}\dotfill \pageref*{derived_noncommutative_geometry} \linebreak \noindent\hyperlink{other_aspects}{Other aspects}\dotfill \pageref*{other_aspects} \linebreak \hypertarget{idea}{}\subsection*{{Idea}}\label{idea} \emph{Differential graded categories} or \emph{dg-categories} are linear analogues of [[spectral categories]]. In other words they are [[linear (infinity,1)-category|linear]] [[stable (infinity,1)-categories]]. It is common and useful to view them as [[enhanced triangulated categories]]. \hypertarget{definition}{}\subsection*{{Definition}}\label{definition} A \emph{dg-category} over a [[commutative ring]] $k$ is an [[(infinity,1)-category]] [[enriched (infinity,1)-category|enriched]] in the [[(infinity,1)-category of chain complexes]] of $k$-[[modules]]. Equivalently, it is an ordinary category [[enriched category|strictly enriched]] in [[chain complexes]] (see \hyperlink{Haugseng13}{Haugseng 13}). Hence a dg-category is a category with [[mapping complexes]] of morphisms between any two objects. By taking the [[homologies]] of these [[chain complexes]] in degree zero, one gets an ordinary category, called the [[homotopy category of a dg-category]]. Notice that a dg-category with a single object is the same thing as a [[dg-algebra]]. \hypertarget{properties}{}\subsection*{{Properties}}\label{properties} \hypertarget{the_infinity1category_of_dgcategories}{}\subsubsection*{{The (infinity,1)-category of dg-categories}}\label{the_infinity1category_of_dgcategories} The [[Dwyer-Kan model structure on dg-categories]] presents the [[(infinity,1)-category of dg-categories]]. \hypertarget{relation_to_stable_categories}{}\subsubsection*{{Relation to stable $\infty$-categories}}\label{relation_to_stable_categories} By the [[stable Dold-Kan correspondence]], the [[(infinity,1)-category]] of dg-categories is equivalent to the [[(infinity,1)-category]] of [[(infinity,1)-categories]] [[enriched (infinity,1)-category|enriched]] in the [[symmetric monoidal (infinity,1)-category]] of [[module spectra|modules]] over the [[Eilenberg-Mac Lane spectrum]] $H k$. The latter is equivalent, at least morally, to the [[(infinity,1)-category]] of $k$-[[linear (infinity,1)-category|linear]] [[stable (infinity,1)-categories]]. More precisely, it is shown in \hyperlink{Cohn13}{Cohn 13} that the [[Morita model structure on dg-categories]] presents the [[(infinity,1)-category]] of [[idempotent complete (infinity,1)-category|idempotent complete]] [[linear (infinity,1)-category|linear]] [[stable (infinity,1)-categories]]. \hypertarget{aspects_of_dgcategories}{}\subsection*{{Aspects of dg-categories}}\label{aspects_of_dgcategories} \begin{itemize}% \item [[homotopy category of a dg-category]]. \item [[equivalence of dg-categories]] \item [[dg-modules]], [[perfect dg-modules]] \item [[derived dg-category]] \item [[dg-Yoneda embedding]] \item [[pretriangulated dg-category]] \item [[dg-localization]], [[dg-quotient]] \item [[dg-nerve]] \item [[Waldhausen K-theory of a dg-category]] \item [[semi-topological K-theory of a dg-category]] \item [[derived moduli stack of objects in a dg-category]] \end{itemize} \hypertarget{related_concepts}{}\subsection*{{Related concepts}}\label{related_concepts} \begin{itemize}% \item [[enhanced triangulated category]] \item [[A-infinity category]] \item [[spectral category]] \item [[stable (infinity,1)-category]] \end{itemize} \hypertarget{references}{}\subsection*{{References}}\label{references} Historically, dg-categories were introduced in \begin{itemize}% \item [[G. M. Kelly]], \emph{Chain maps inducing zero homology maps}, Proc. Cambridge Philos. Soc. 61 (1965), 847--854, \end{itemize} whilst their modern development can be traced to \begin{itemize}% \item [[A. I. Bondal]], [[Mikhail Kapranov]], \emph{Enhanced triangulated categories}, . , 181 (1990), No.5, 669--683 (Russian); transl. in USSR Math. USSR Sbornik, vol. 70 (1991), No. 1, pp. 93--107, (MR91g:18010) ([[bondalKaprEnhTRiangCat.pdf:file]]) \end{itemize} \hypertarget{overviews}{}\subsubsection*{{Overviews}}\label{overviews} For concise reviews of the theory, see section 1 of \begin{itemize}% \item [[A. Beilinson]], [[V. Vologodsky]], \emph{DG guide to Voevodsky's motives}. \end{itemize} as well as the introduction and appendices to \begin{itemize}% \item [[V. Drinfeld]], \emph{DG quotients of DG categories}, \href{http://www.math.harvard.edu/~gaitsgde/grad_2009/DGquotients.pdf}{pdf}. \end{itemize} For longer surveys, see \begin{itemize}% \item [[Bernhard Keller]], \emph{On differential graded categories} International Congress of Mathematicians. Vol. II, 151--190, Eur. Math. Soc., Z\"u{}rich, 2006. (\href{http://arxiv.org/abs/math/0601185}{arXiv}) \end{itemize} and \begin{itemize}% \item [[Bertrand Toën]], \emph{Lectures on dg-categories} (\href{https://perso.math.univ-toulouse.fr/btoen/files/2012/04/swisk.pdf}{pdf}). \end{itemize} \hypertarget{homotopy_theory_of_dgcategories}{}\subsubsection*{{Homotopy theory of dg-categories}}\label{homotopy_theory_of_dgcategories} The [[homotopy theory]] of [[dg-categories]] is studied in \begin{itemize}% \item [[Gonçalo Tabuada]], \emph{Homotopy theory of DG categories}, Thesis, Paris, 2007, \href{http://people.math.jussieu.fr/~keller/TabuadaThese.pdf}{pdf}. \item [[Gonçalo Tabuada]], \emph{Une structure de cat\'e{}gorie de mod\`e{}les de Quillen sur la cat\'e{}gorie des dg-cat\'e{}gories}, C. R. Math. Acad. Sci. Paris 340 (2005), no. 1, 15--19. \end{itemize} The equivalence with the [[homotopy theory]] of [[stable (infinity,1)-categories]] is discussed in \begin{itemize}% \item [[Lee Cohn]], \emph{Differential Graded Categories are k-linear Stable Infinity Categories} (\href{http://arxiv.org/abs/1308.2587}{arXiv:1308.2587}) \end{itemize} (Note that the proof works over any ring, even though it is stated there for [[characteristic zero]].) In the following it is shown that the [[homotopy theory]] of [[(infinity,1)-categories]] enriched in the [[(infinity,1)-category]] of [[chain complexes]] is equivalent to the [[homotopy theory]] of ordinary categories strictly enriched in [[chain complexes]]. \begin{itemize}% \item [[Rune Haugseng]], \emph{Rectification of enriched infinity-categories}, \href{http://arxiv.org/abs/1312.3881v2}{arXiv:1312.3881}. \end{itemize} \hypertarget{derived_noncommutative_geometry}{}\subsubsection*{{Derived noncommutative geometry}}\label{derived_noncommutative_geometry} The following references discuss the use of dg-categories in [[derived noncommutative algebraic geometry]] and [[noncommutative motives]]. \begin{itemize}% \item [[Gonçalo Tabuada]], \emph{Invariants additifs de DG-cat\'e{}gories}, Int. Math. Res. Not. 2005, no. 53, 3309--3339; Addendum in Int. Math. Res. Not. 2006, Art. ID 75853, 3 pp. ; Erratum in Int. Math. Res. Not. IMRN 2007, no. 24, Art. ID rnm149, 17 pp. \item [[Marco Robalo]], \emph{Th\'e{}orie homotopique motivique des espaces noncommutatifs}, \href{http://webusers.imj-prg.fr/~marco.robalo/these.pdf}{pdf}. \item S. Mahanta, \emph{Noncommutative geometry in the framework of differential graded categories}, () \item D. Orlov, \emph{Smooth and proper noncommutative schemes and gluing of DG categories}, Adv. Math. 302 (2014) \href{https://dx.doi.org/10.1016/j.aim.2016.07.014}{doi} \end{itemize} \hypertarget{other_aspects}{}\subsubsection*{{Other aspects}}\label{other_aspects} \begin{itemize}% \item [[Bernhard Keller]], \emph{Deriving DG categories}, Ann. Sci. \'E{}cole Norm. Sup. (4) 27 (1994), no. 1, 63--102 () \item [[Dmitry Tamarkin]], \emph{What do dg-categories form?}, Compos. Math. 143 (2007), no. 5, 1335--1358. \item [[Michael Batanin|M. Batanin]], \emph{What do dg-categories form} (after Tamarkin), talks at Paris 7 and Australian category seminar (), \href{http://arxiv.org/abs/math.CT/0606553}{math.CT/0606553} \item [[Oren Ben-Bassat]], [[Jonathan Block]], \emph{Cohesive DG categories I: Milnor descent}, \href{http://arxiv.org/abs/1201.6118}{arxiv/1201.6118} \end{itemize} [[!redirects dg-category]] [[!redirects dg-categories]] [[!redirects dg category]] [[!redirects dg categories]] [[!redirects DG-category]] [[!redirects DG-categories]] [[!redirects DG category]] [[!redirects DG categories]] [[!redirects differential graded category]] [[!redirects differential graded categories]] \end{document}