\documentclass[12pt,titlepage]{article} \usepackage{amsmath} \usepackage{mathrsfs} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsthm} \usepackage{mathtools} \usepackage{graphicx} \usepackage{color} \usepackage{ucs} \usepackage[utf8x]{inputenc} \usepackage{xparse} \usepackage{hyperref} %----Macros---------- % % Unresolved issues: % % \righttoleftarrow % \lefttorightarrow % % \color{} with HTML colorspec % \bgcolor % \array with options (without options, it's equivalent to the matrix environment) % Of the standard HTML named colors, white, black, red, green, blue and yellow % are predefined in the color package. Here are the rest. \definecolor{aqua}{rgb}{0, 1.0, 1.0} \definecolor{fuschia}{rgb}{1.0, 0, 1.0} \definecolor{gray}{rgb}{0.502, 0.502, 0.502} \definecolor{lime}{rgb}{0, 1.0, 0} \definecolor{maroon}{rgb}{0.502, 0, 0} \definecolor{navy}{rgb}{0, 0, 0.502} \definecolor{olive}{rgb}{0.502, 0.502, 0} \definecolor{purple}{rgb}{0.502, 0, 0.502} \definecolor{silver}{rgb}{0.753, 0.753, 0.753} \definecolor{teal}{rgb}{0, 0.502, 0.502} % Because of conflicts, \space and \mathop are converted to % \itexspace and \operatorname during preprocessing. % itex: \space{ht}{dp}{wd} % % Height and baseline depth measurements are in units of tenths of an ex while % the width is measured in tenths of an em. \makeatletter \newdimen\itex@wd% \newdimen\itex@dp% \newdimen\itex@thd% \def\itexspace#1#2#3{\itex@wd=#3em% \itex@wd=0.1\itex@wd% \itex@dp=#2ex% \itex@dp=0.1\itex@dp% \itex@thd=#1ex% \itex@thd=0.1\itex@thd% \advance\itex@thd\the\itex@dp% \makebox[\the\itex@wd]{\rule[-\the\itex@dp]{0cm}{\the\itex@thd}}} \makeatother % \tensor and \multiscript \makeatletter \newif\if@sup \newtoks\@sups \def\append@sup#1{\edef\act{\noexpand\@sups={\the\@sups #1}}\act}% \def\reset@sup{\@supfalse\@sups={}}% \def\mk@scripts#1#2{\if #2/ \if@sup ^{\the\@sups}\fi \else% \ifx #1_ \if@sup ^{\the\@sups}\reset@sup \fi {}_{#2}% \else \append@sup#2 \@suptrue \fi% \expandafter\mk@scripts\fi} \def\tensor#1#2{\reset@sup#1\mk@scripts#2_/} \def\multiscripts#1#2#3{\reset@sup{}\mk@scripts#1_/#2% \reset@sup\mk@scripts#3_/} \makeatother % \slash \makeatletter \newbox\slashbox \setbox\slashbox=\hbox{$/$} \def\itex@pslash#1{\setbox\@tempboxa=\hbox{$#1$} \@tempdima=0.5\wd\slashbox \advance\@tempdima 0.5\wd\@tempboxa \copy\slashbox \kern-\@tempdima \box\@tempboxa} \def\slash{\protect\itex@pslash} \makeatother % math-mode versions of \rlap, etc % from Alexander Perlis, "A complement to \smash, \llap, and lap" % http://math.arizona.edu/~aprl/publications/mathclap/ \def\clap#1{\hbox to 0pt{\hss#1\hss}} \def\mathllap{\mathpalette\mathllapinternal} \def\mathrlap{\mathpalette\mathrlapinternal} \def\mathclap{\mathpalette\mathclapinternal} \def\mathllapinternal#1#2{\llap{$\mathsurround=0pt#1{#2}$}} \def\mathrlapinternal#1#2{\rlap{$\mathsurround=0pt#1{#2}$}} \def\mathclapinternal#1#2{\clap{$\mathsurround=0pt#1{#2}$}} % Renames \sqrt as \oldsqrt and redefine root to result in \sqrt[#1]{#2} \let\oldroot\root \def\root#1#2{\oldroot #1 \of{#2}} \renewcommand{\sqrt}[2][]{\oldroot #1 \of{#2}} % Manually declare the txfonts symbolsC font \DeclareSymbolFont{symbolsC}{U}{txsyc}{m}{n} \SetSymbolFont{symbolsC}{bold}{U}{txsyc}{bx}{n} \DeclareFontSubstitution{U}{txsyc}{m}{n} % Manually declare the stmaryrd font \DeclareSymbolFont{stmry}{U}{stmry}{m}{n} \SetSymbolFont{stmry}{bold}{U}{stmry}{b}{n} % Manually declare the MnSymbolE font \DeclareFontFamily{OMX}{MnSymbolE}{} \DeclareSymbolFont{mnomx}{OMX}{MnSymbolE}{m}{n} \SetSymbolFont{mnomx}{bold}{OMX}{MnSymbolE}{b}{n} \DeclareFontShape{OMX}{MnSymbolE}{m}{n}{ <-6> MnSymbolE5 <6-7> MnSymbolE6 <7-8> MnSymbolE7 <8-9> MnSymbolE8 <9-10> MnSymbolE9 <10-12> MnSymbolE10 <12-> MnSymbolE12}{} % Declare specific arrows from txfonts without loading the full package \makeatletter \def\re@DeclareMathSymbol#1#2#3#4{% \let#1=\undefined \DeclareMathSymbol{#1}{#2}{#3}{#4}} \re@DeclareMathSymbol{\neArrow}{\mathrel}{symbolsC}{116} \re@DeclareMathSymbol{\neArr}{\mathrel}{symbolsC}{116} \re@DeclareMathSymbol{\seArrow}{\mathrel}{symbolsC}{117} \re@DeclareMathSymbol{\seArr}{\mathrel}{symbolsC}{117} \re@DeclareMathSymbol{\nwArrow}{\mathrel}{symbolsC}{118} \re@DeclareMathSymbol{\nwArr}{\mathrel}{symbolsC}{118} \re@DeclareMathSymbol{\swArrow}{\mathrel}{symbolsC}{119} \re@DeclareMathSymbol{\swArr}{\mathrel}{symbolsC}{119} \re@DeclareMathSymbol{\nequiv}{\mathrel}{symbolsC}{46} \re@DeclareMathSymbol{\Perp}{\mathrel}{symbolsC}{121} \re@DeclareMathSymbol{\Vbar}{\mathrel}{symbolsC}{121} \re@DeclareMathSymbol{\sslash}{\mathrel}{stmry}{12} \re@DeclareMathSymbol{\bigsqcap}{\mathop}{stmry}{"64} \re@DeclareMathSymbol{\biginterleave}{\mathop}{stmry}{"6} \re@DeclareMathSymbol{\invamp}{\mathrel}{symbolsC}{77} \re@DeclareMathSymbol{\parr}{\mathrel}{symbolsC}{77} \makeatother % \llangle, \rrangle, \lmoustache and \rmoustache from MnSymbolE \makeatletter \def\Decl@Mn@Delim#1#2#3#4{% \if\relax\noexpand#1% \let#1\undefined \fi \DeclareMathDelimiter{#1}{#2}{#3}{#4}{#3}{#4}} \def\Decl@Mn@Open#1#2#3{\Decl@Mn@Delim{#1}{\mathopen}{#2}{#3}} \def\Decl@Mn@Close#1#2#3{\Decl@Mn@Delim{#1}{\mathclose}{#2}{#3}} \Decl@Mn@Open{\llangle}{mnomx}{'164} \Decl@Mn@Close{\rrangle}{mnomx}{'171} \Decl@Mn@Open{\lmoustache}{mnomx}{'245} \Decl@Mn@Close{\rmoustache}{mnomx}{'244} \makeatother % Widecheck \makeatletter \DeclareRobustCommand\widecheck[1]{{\mathpalette\@widecheck{#1}}} \def\@widecheck#1#2{% \setbox\z@\hbox{\m@th$#1#2$}% \setbox\tw@\hbox{\m@th$#1% \widehat{% \vrule\@width\z@\@height\ht\z@ \vrule\@height\z@\@width\wd\z@}$}% \dp\tw@-\ht\z@ \@tempdima\ht\z@ \advance\@tempdima2\ht\tw@ \divide\@tempdima\thr@@ \setbox\tw@\hbox{% \raise\@tempdima\hbox{\scalebox{1}[-1]{\lower\@tempdima\box \tw@}}}% {\ooalign{\box\tw@ \cr \box\z@}}} \makeatother % \mathraisebox{voffset}[height][depth]{something} \makeatletter \NewDocumentCommand\mathraisebox{moom}{% \IfNoValueTF{#2}{\def\@temp##1##2{\raisebox{#1}{$\m@th##1##2$}}}{% \IfNoValueTF{#3}{\def\@temp##1##2{\raisebox{#1}[#2]{$\m@th##1##2$}}% }{\def\@temp##1##2{\raisebox{#1}[#2][#3]{$\m@th##1##2$}}}}% \mathpalette\@temp{#4}} \makeatletter % udots (taken from yhmath) \makeatletter \def\udots{\mathinner{\mkern2mu\raise\p@\hbox{.} \mkern2mu\raise4\p@\hbox{.}\mkern1mu \raise7\p@\vbox{\kern7\p@\hbox{.}}\mkern1mu}} \makeatother %% Fix array \newcommand{\itexarray}[1]{\begin{matrix}#1\end{matrix}} %% \itexnum is a noop \newcommand{\itexnum}[1]{#1} %% Renaming existing commands \newcommand{\underoverset}[3]{\underset{#1}{\overset{#2}{#3}}} \newcommand{\widevec}{\overrightarrow} \newcommand{\darr}{\downarrow} \newcommand{\nearr}{\nearrow} \newcommand{\nwarr}{\nwarrow} \newcommand{\searr}{\searrow} \newcommand{\swarr}{\swarrow} \newcommand{\curvearrowbotright}{\curvearrowright} \newcommand{\uparr}{\uparrow} \newcommand{\downuparrow}{\updownarrow} \newcommand{\duparr}{\updownarrow} \newcommand{\updarr}{\updownarrow} \newcommand{\gt}{>} \newcommand{\lt}{<} \newcommand{\map}{\mapsto} \newcommand{\embedsin}{\hookrightarrow} \newcommand{\Alpha}{A} \newcommand{\Beta}{B} \newcommand{\Zeta}{Z} \newcommand{\Eta}{H} \newcommand{\Iota}{I} \newcommand{\Kappa}{K} \newcommand{\Mu}{M} \newcommand{\Nu}{N} \newcommand{\Rho}{P} \newcommand{\Tau}{T} \newcommand{\Upsi}{\Upsilon} \newcommand{\omicron}{o} \newcommand{\lang}{\langle} \newcommand{\rang}{\rangle} \newcommand{\Union}{\bigcup} \newcommand{\Intersection}{\bigcap} \newcommand{\Oplus}{\bigoplus} \newcommand{\Otimes}{\bigotimes} \newcommand{\Wedge}{\bigwedge} \newcommand{\Vee}{\bigvee} \newcommand{\coproduct}{\coprod} \newcommand{\product}{\prod} \newcommand{\closure}{\overline} \newcommand{\integral}{\int} \newcommand{\doubleintegral}{\iint} \newcommand{\tripleintegral}{\iiint} \newcommand{\quadrupleintegral}{\iiiint} \newcommand{\conint}{\oint} \newcommand{\contourintegral}{\oint} \newcommand{\infinity}{\infty} \newcommand{\bottom}{\bot} \newcommand{\minusb}{\boxminus} \newcommand{\plusb}{\boxplus} \newcommand{\timesb}{\boxtimes} \newcommand{\intersection}{\cap} \newcommand{\union}{\cup} \newcommand{\Del}{\nabla} \newcommand{\odash}{\circleddash} \newcommand{\negspace}{\!} \newcommand{\widebar}{\overline} \newcommand{\textsize}{\normalsize} \renewcommand{\scriptsize}{\scriptstyle} \newcommand{\scriptscriptsize}{\scriptscriptstyle} \newcommand{\mathfr}{\mathfrak} \newcommand{\statusline}[2]{#2} \newcommand{\tooltip}[2]{#2} \newcommand{\toggle}[2]{#2} % Theorem Environments \theoremstyle{plain} \newtheorem{theorem}{Theorem} \newtheorem{lemma}{Lemma} \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*{t-structure} \hypertarget{context}{}\subsubsection*{{Context}}\label{context} \hypertarget{stable_homotopy_theory}{}\paragraph*{{Stable Homotopy theory}}\label{stable_homotopy_theory} [[!include stable homotopy theory - contents]] \hypertarget{contents}{}\section*{{Contents}}\label{contents} \noindent\hyperlink{definition}{Definition}\dotfill \pageref*{definition} \linebreak \noindent\hyperlink{in_stable_categories}{In stable $\infty$-categories}\dotfill \pageref*{in_stable_categories} \linebreak \noindent\hyperlink{towers}{Towers}\dotfill \pageref*{towers} \linebreak \noindent\hyperlink{properties}{Properties}\dotfill \pageref*{properties} \linebreak \noindent\hyperlink{general}{General}\dotfill \pageref*{general} \linebreak \noindent\hyperlink{application_to_spectral_sequence}{Application to spectral sequence}\dotfill \pageref*{application_to_spectral_sequence} \linebreak \noindent\hyperlink{related_concepts}{Related concepts}\dotfill \pageref*{related_concepts} \linebreak \noindent\hyperlink{references}{References}\dotfill \pageref*{references} \linebreak \hypertarget{definition}{}\subsection*{{Definition}}\label{definition} \begin{defn} \label{tStruc}\hypertarget{tStruc}{} Let $C$ be a [[triangulated category]]. A \emph{t-structure} on $C$ is a [[pair]] $\mathfrak{t}=(C_{\ge 0}, C_{\le 0})$ of [[strictly full subcategories]] \begin{displaymath} C_{\geq 0}, C_{\leq 0} \hookrightarrow C \end{displaymath} such that \begin{enumerate}% \item for all $X \in C_{\geq 0}$ and $Y \in C_{\leq 0}$ the [[hom object]] is the [[zero object]]: $Hom_{C}(X, Y[-1]) = 0$; \item the subcategories are closed under [[suspension]]/desuspension: $C_{\geq 0}[1] \subset C_{\geq 0}$ and $C_{\leq 0}[-1] \subset C_{\leq 0}$. \item For all [[objects]] $X \in C$ there is a [[fiber sequence]] $Y \to X \to Z$ with $Y \in C_{\geq 0}$ and $Z \in C_{\leq 0}[-1]$. \end{enumerate} \end{defn} \begin{defn} \label{}\hypertarget{}{} Given a t-structure, its \emph{heart} is the intersection \begin{displaymath} C_{\geq 0} \cap C_{\leq 0} \hookrightarrow C \,. \end{displaymath} \end{defn} \hypertarget{in_stable_categories}{}\subsubsection*{{In stable $\infty$-categories}}\label{in_stable_categories} In the [[infinity-category|infinity-categorical]] setting $t$-structures arise as [[torsion theory|torsion/torsionfree]] classes associated to suitable [[orthogonal factorization system|factorization systems]] on a [[stable infinity-category]] $C$. \begin{itemize}% \item In a stable setting, the subcategories are closed under de/suspension simply because they are co/reflective and reflective and these operations are co/limits. Co/reflective subcategories of $C$ arise from co/[[reflective factorization systems]] on $C$; \item A \emph{bireflective} factorization system on a $\infty$-category $C$ consists of a [[orthogonal factorization system|factorization system]] $\mathbb{F}=(E,M)$ where both classes satisfy the [[two-out-of-three]] property. \item A bireflective factorization system $(E,M)$ on a stable $\infty$-category $C$ is called \emph{normal} if the diagram $S x\to x\to R x$ obtained from the reflection $R\colon C\to M/0$ and the coreflection $S\colon C\to *\!/E$ (where the category $M/\!* =\{A\mid (0\to A)\in M\}$ is obtained as $\Psi(E,M)$ under the adjunction $\Phi\dashv \Psi$ described at [[reflective factorization system]] and in \hyperlink{CHK}{CHK}; see also \hyperlink{FL0}{FL0, \S{}1.1}) is \emph{exact}, meaning that the square in \begin{displaymath} \begin{array}{cccccc} 0 &\to& S X &\to& X\\ && \downarrow&&\downarrow\\ && 0 &\to& R X\\ && && \downarrow\\ && && 0 \end{array} \end{displaymath} is a fiber sequence for any object $X$; see \hyperlink{FL0}{FL0, Def 3.5 and Prop. 3.10} for equivalent conditions for normality. \end{itemize} \textbf{Remark.} \hyperlink{CHK}{CHK} established a hierarchy between the three notions of simple, semi-exact and normal factorization system: in the setting of stable $\infty$-category the three notions turn out to be equivalent: see \hyperlink{FL0}{FL0, Thm 3.11}. \textbf{Theorem.} There is a bijective correspondence between the class $TS( C )$ of $t$-structures and the class of normal torsion theories on a stable $\infty$-category $C$, induced by the following correspondence: \begin{itemize}% \item On the one side, given a normal, bireflective factorization system $(E,M)$ on $C$ we define the two classes $(C_{\ge0}(\mathbb{F}), C_{\lt 0}(\mathbb{F}))$ of a $t$-structure $\mathfrak{t}(\mathbb{F})$ to be the torsion and torsionfree classes $(*\!/E, M/\!*)$ associated to the factorization $(E,M)$. \item On the other side, given a $t$-structure on $C$ we set\begin{displaymath} E(t)=\{f\in C^{\Delta[1]} \mid \tau_{\lt 0}(f) \;\text{ is an equivalence}\}; \end{displaymath} \begin{displaymath} M(t)=\{f\in C^{\Delta[1]} \mid \tau_{\geq0}(f) \;\text{ is an equivalence}\}. \end{displaymath} \end{itemize} \emph{Proof.} This is \hyperlink{FL0}{FL0, Theorem 3.13} \textbf{Theorem.} There is a natural monotone action of the group $\mathbb{Z}$ of integers on the class $TS( C )$ (now confused with the class $FS_\nu( C )$ of normal torsion theories on $C$) given by the suspension functor: $\mathbb{F}=(E,M)$ goes to $\mathbb{F}[1] = (E[1], M[1])$. This correspondence leads to study \emph{families} of $t$-structures $\{\mathbb{F}_i\}_{i\in I}$; more precisely, we are led to study \emph{$\mathbb{Z}$-equivariant} [[k-ary factorization system|multiple factorization systems]] $J\to TS( C )$. \textbf{Theorem.} Let $\mathfrak{t} \in TS(C)$ and $\mathbb{F}=(E,M)$ correspond each other under the above bijection; then the following conditions are equivalent: \begin{enumerate}% \item $\mathfrak{t}[1]=\mathfrak{t}$, i.e. $C_{\geq 1}= C_{\geq 0}$; \item $C_{\geq 0}=*\!/E$ is a stable $\infty$-category; \item the class $E$ is closed under pullback. \end{enumerate} In each of these cases, we say that $\mathfrak{t}$ or $(E,M)$ is \emph{stable}. \emph{Proof.} This is \hyperlink{FL1}{FL1, Theorem 2.16} This results allows us to recognize \emph{$t$-structures with stable classes} precisely as those which are fixed in the natural $\mathbb{Z}$-action on $TS( C )$. Two ``extremal'' choices of $\mathbb{Z}$-chains of $t$-structures draw a connection between two apparently separated constructions in the theory of derived categories: \emph{Harder-Narashiman filtrations} and \emph{semiorthogonal decompositions} on triangulated categories: we adopt the shorthand $\mathfrak{t}_{1,\dots, n}$ to denote the tuple $\mathfrak{t}_1\preceq \mathfrak{t}_2\preceq\cdots\preceq \mathfrak{t}_n$, each of the $\mathfrak{t}_i$ being a $t$-structure $((C_i)_{\ge 0}, (C_i)_{\lt 0})$ on $C$, and we denote similarly $\mathfrak{t}_\omega$. Then \begin{itemize}% \item In the \emph{stable case} the tuple $t_{1,\dots, n}$ is endowed with a (monotone) $\mathbb{Z}$-action, and the map $\{0\lt 1\cdots\lt n\}\to TS( C )$ is equivariant with respect to this action; the absence of nontrivial $\mathbb{Z}$-actions on $\{0\lt 1\cdots\lt n\}$ forces each $t_i$ to be stable. \item In the \emph{orbit case} we consider an \emph{infinite} family $t_\omega$ of $t$-structures on $C$, obtained as the orbit of a fixed $(E_0, M_0)\in TS( C )$ with respect to the natural $\mathbb{Z}$-action. \end{itemize} \hypertarget{towers}{}\subsubsection*{{Towers}}\label{towers} The HN-filtration induced by a $t$-structure and the factorization induced by a [[semiorthogonal decomposition]] on $C$ both are the byproduct of the \emph{tower} associated to a tuple $\mathfrak{t}_{1,\dots, n}$: (\ldots{}) \hypertarget{properties}{}\subsection*{{Properties}}\label{properties} \hypertarget{general}{}\subsubsection*{{General}}\label{general} \begin{prop} \label{}\hypertarget{}{} The heart of a stable $(\infty,1)$-category is an [[abelian category]]. \end{prop} (\hyperlink{BBD82}{BBD 82}, [[Higher Algebra|Higher Algebra, remark 1.2.1.12]], \hyperlink{FL0}{FL0, Ex. 4.1} and \hyperlink{FL1}{FL1, \S{}3.1}) \hypertarget{application_to_spectral_sequence}{}\subsubsection*{{Application to spectral sequence}}\label{application_to_spectral_sequence} If a the heart of a t-structure on a [[stable (∞,1)-category]] with [[sequential limits]] is an [[abelian category]], then the [[spectral sequence of a filtered stable homotopy type]] converges (see there). \hypertarget{related_concepts}{}\subsection*{{Related concepts}}\label{related_concepts} \begin{itemize}% \item [[Bridgeland stability]] \end{itemize} \hypertarget{references}{}\subsection*{{References}}\label{references} For triangulated categories \begin{itemize}% \item S. I. Gelfand, [[Yuri Manin]], \emph{Methods of homological algebra}, Nauka 1988, Springer 1998, 2003 \item [[Donu Arapura]], \emph{Triangulated categories and $t$-structures} (\href{http://www.math.purdue.edu/~dvb/preprints/perv2.pdf}{pdf}) \item [[Alexander Beilinson]], [[Joseph Bernstein]], [[Pierre Deligne]], \emph{Faisceaux pervers}, Asterisque \textbf{100}, Volume 1, 1982 \end{itemize} \begin{itemize}% \item D. Abramovich, A. Polishchuk, \emph{Sheaves of t-structures and valuative criteria for stable complexes}, J. reine angew. Math. \textbf{590} (2006), 89--130 \item A. L. Gorodentsev, S. A. Kuleshov, A. N. Rudakov, \emph{t-stabilities and t-structures on triangulated categories}, Izv. Ross. Akad. Nauk Ser. Mat. \textbf{68} (2004), no. 4, 117--150 \item A. Polishchuk, \emph{Constant families of t-structures on derived categories of coherent sheaves}, Moscow Math. J. \textbf{7} (2007), 109--134 \item John Collins, [[Alexander Polishchuk]], \emph{Gluing stability conditions}, \href{http://arxiv.org/abs/0902.0323}{arxiv/0902.0323} \end{itemize} For [[stable (∞,1)-categories]] \begin{itemize}% \item [[Jacob Lurie]], \emph{[[Higher Algebra]]} \end{itemize} For reflective factorization systems and normal torsion theories in stable $\infty$-categories \begin{itemize}% \item Cassidy and H\'e{}bert and [[Max Kelly|Kelly]], ``Reflective subcategories, localizations, and factorization systems''. \emph{J. Austral. Math Soc. (Series A)} 38 (1985), 287--329 (\href{http://journals.cambridge.org/download.php?file=%2FJAZ%2FJAZ1_38_03%2FS1446788700023624a.pdf&code=5796045be8904c5183c2e95bce65491e}{pdf}) \end{itemize} \begin{itemize}% \item [[Jiri Rosicky]], [[Walter Tholen]], \emph{Factorization, Fibration and Torsion}, Journal of Homotopy and Related Structures, Vol. 2(2007), No. 2, pp. 295-314 (\href{http://arxiv.org/abs/0801.0063}{arXiv:0801.0063}, \href{http://www.emis.de/journals/JHRS/volumes/2007/n2a14/}{publisher}) \end{itemize} \begin{itemize}% \item [[Domenico Fiorenza]] and [[Fosco Loregian]], ``$t$-structures are normal torsion theories'' (\href{http://arxiv.org/abs/1408.7003}{arxiv}). \item [[Domenico Fiorenza]] and [[Fosco Loregian]], ``Hearts and Postnikov towers in stable $\infty$-categories'' (in preparation). \end{itemize} [[!redirects t-structures]] [[!redirects t-structure on a stable (∞,1)-category]] [[!redirects t-structures on a stable (∞,1)-category]] [[!redirects t-structure on a stable (infinity,1)-category]] [[!redirects t-structures on a stable (infinity,1)-category]] [[!redirects heart]] [[!redirects hearts]] [[!redirects heart of a t-structure]] [[!redirects hearts of t-structures]] [[!redirects heart of a stable (∞,1)-category]] [[!redirects hearts of stable (∞,1)-categories]] [[!redirects heart of a stable (infinity,1)-category]] [[!redirects hearts of stable (infinity,1)-categories]] \end{document}