\documentclass[12pt,titlepage]{article} \usepackage{amsmath} \usepackage{mathrsfs} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsthm} \usepackage{mathtools} \usepackage{mathbbol} \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*{configuration space of points} \hypertarget{context}{}\subsubsection*{{Context}}\label{context} \hypertarget{topology}{}\paragraph*{{Topology}}\label{topology} [[!include topology - 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{ordered_unlabeled_points}{Ordered unlabeled points}\dotfill \pageref*{ordered_unlabeled_points} \linebreak \noindent\hyperlink{unordered_unlabeled_points}{Unordered unlabeled points}\dotfill \pageref*{unordered_unlabeled_points} \linebreak \noindent\hyperlink{UnorderedLabeledPoints}{Unordered labeled points}\dotfill \pageref*{UnorderedLabeledPoints} \linebreak \noindent\hyperlink{properties}{Properties}\dotfill \pageref*{properties} \linebreak \noindent\hyperlink{OrderedUnlabeledConfigurationsFromUnorderedLabeledConfigurations}{Ordered unlabeled configurations from unordered labeled configurations}\dotfill \pageref*{OrderedUnlabeledConfigurationsFromUnorderedLabeledConfigurations} \linebreak \noindent\hyperlink{cohomotopy_charge_map}{Cohomotopy charge map}\dotfill \pageref*{cohomotopy_charge_map} \linebreak \noindent\hyperlink{LoopSpacesOfSuspensions}{Relation to iterated loop spaces of iterated suspensions}\dotfill \pageref*{LoopSpacesOfSuspensions} \linebreak \noindent\hyperlink{relation_to_classifying_space_of_the_symmetric_group}{Relation to classifying space of the symmetric group}\dotfill \pageref*{relation_to_classifying_space_of_the_symmetric_group} \linebreak \noindent\hyperlink{relation_to_james_construction}{Relation to James construction}\dotfill \pageref*{relation_to_james_construction} \linebreak \noindent\hyperlink{RelationToTwistedCohomotopy}{In twisted Cohomotopy}\dotfill \pageref*{RelationToTwistedCohomotopy} \linebreak \noindent\hyperlink{action_by_little_disk_operad_and_by_goodwillie_derivatives}{Action by little $n$-disk operad and by Goodwillie derivatives}\dotfill \pageref*{action_by_little_disk_operad_and_by_goodwillie_derivatives} \linebreak \noindent\hyperlink{HomologyAndStabilization}{Homology and stabilization in homology}\dotfill \pageref*{HomologyAndStabilization} \linebreak \noindent\hyperlink{RationalHomotopyType}{Rational homotopy type}\dotfill \pageref*{RationalHomotopyType} \linebreak \noindent\hyperlink{Cohomology}{Rational cohomology}\dotfill \pageref*{Cohomology} \linebreak \noindent\hyperlink{RationalHomotopyGroups}{Rational homotopy and Whitehead products}\dotfill \pageref*{RationalHomotopyGroups} \linebreak \noindent\hyperlink{OccurrencesAndApplications}{Occurrences and Applications}\dotfill \pageref*{OccurrencesAndApplications} \linebreak \noindent\hyperlink{compactification}{Compactification}\dotfill \pageref*{compactification} \linebreak \noindent\hyperlink{stable_splitting_of_mapping_spaces}{Stable splitting of mapping spaces}\dotfill \pageref*{stable_splitting_of_mapping_spaces} \linebreak \noindent\hyperlink{correlators_as_differential_forms_on_configuration_spaces}{Correlators as differential forms on configuration spaces}\dotfill \pageref*{correlators_as_differential_forms_on_configuration_spaces} \linebreak \noindent\hyperlink{related_concepts}{Related concepts}\dotfill \pageref*{related_concepts} \linebreak \noindent\hyperlink{references}{References}\dotfill \pageref*{references} \linebreak \noindent\hyperlink{general}{General}\dotfill \pageref*{general} \linebreak \noindent\hyperlink{cohomotopy_charge_map_2}{Cohomotopy charge map}\dotfill \pageref*{cohomotopy_charge_map_2} \linebreak \noindent\hyperlink{stable_splitting_of_mapping_spaces_2}{Stable splitting of mapping spaces}\dotfill \pageref*{stable_splitting_of_mapping_spaces_2} \linebreak \noindent\hyperlink{ReferencesInGoodwillieCalculus}{In Goodwillie-calculus}\dotfill \pageref*{ReferencesInGoodwillieCalculus} \linebreak \noindent\hyperlink{ReferencesCompactification}{Compactification}\dotfill \pageref*{ReferencesCompactification} \linebreak \noindent\hyperlink{ReferencesCohomology}{Homology and cohomology}\dotfill \pageref*{ReferencesCohomology} \linebreak \noindent\hyperlink{homotopy}{Homotopy}\dotfill \pageref*{homotopy} \linebreak \noindent\hyperlink{rational_homotopy_type_2}{Rational homotopy type}\dotfill \pageref*{rational_homotopy_type_2} \linebreak \noindent\hyperlink{cohomology_modeled_by_graph_complexes}{Cohomology modeled by graph complexes}\dotfill \pageref*{cohomology_modeled_by_graph_complexes} \linebreak \noindent\hyperlink{ReferencesLoopSpacesOfConfigurationSpaces}{Loop spaces of configuration spaces of points}\dotfill \pageref*{ReferencesLoopSpacesOfConfigurationSpaces} \linebreak \noindent\hyperlink{AsModuliOfD0D4BraneBoundStates}{As moduli of Dp-D(p+4)-brane bound states:}\dotfill \pageref*{AsModuliOfD0D4BraneBoundStates} \linebreak \hypertarget{idea}{}\subsection*{{Idea}}\label{idea} In [[mathematics]], the term ``configuration space'' of a [[topological space]] $X$ typically refers by default to the topological space of pairwise distinct [[element|points]] in $X$, also called \emph{[[Fadell's configuration space]]}, for emphasis. In principle many other kinds of configurations and the spaces these form may be referred to by ``configuration space'', notably in [[physics]] the usage is in a broader sense, see at \emph{[[configuration space (physics)]]}. \hypertarget{Definition}{}\subsection*{{Definition}}\label{Definition} Several variants of configuration spaces of points are of interest. They differ in whether \begin{enumerate}% \item points are linearly ordered or not; \item points are labeled in some labelling space; \item points vanish on some subspace or if their labels are in some subspace. \end{enumerate} Here are some of these variant definitions: \hypertarget{ordered_unlabeled_points}{}\subsubsection*{{Ordered unlabeled points}}\label{ordered_unlabeled_points} \begin{defn} \label{OrderedUnlabeledConfigurations}\hypertarget{OrderedUnlabeledConfigurations}{} \textbf{(ordered unlabled configurations of a fixed number of points)} Let $X$ be a [[closed manifold|closed]] [[smooth manifold]]. For $n \in \mathbb{N}$ write \begin{displaymath} \underset{ {}^{\{1,\cdots, n\}} }{ Conf } \big( X \big) \;\coloneqq\; \big( X \big)^n \setminus \mathbf{\Delta}^n_X \end{displaymath} for the [[complement]] of the [[fat diagonal]] inside the $n$-fold [[Cartesian product]] of $X$ with itself. This is the space of ordered but otherwise unlabeled configurations of $n$ points\_ in $X$. \end{defn} $\backslash$linebreak \hypertarget{unordered_unlabeled_points}{}\subsubsection*{{Unordered unlabeled points}}\label{unordered_unlabeled_points} \begin{defn} \label{UnorderedUnlabeledConfigurations}\hypertarget{UnorderedUnlabeledConfigurations}{} \textbf{(unordered unlabled configurations of a fixed number of points)} Let $X$ be a [[closed manifold|closed]] [[smooth manifold]], For $n \in \mathbb{N}$ write \begin{equation} \begin{aligned} Conf_n \big( X \big) & \coloneqq \; \Big( \underset{{}^{1,\cdots,n}}{Conf} \big( X \big) \big) / Sym(n) \\ & =\; \Big( \big( X \big)^n \setminus \mathbf{\Delta}^n_X \Big) / Sym(n) \end{aligned} \label{UnorderedUnlabelednPointConfigurationSpaces}\end{equation} for the [[quotient space]] of the ordered configuration space (Def. \ref{OrderedUnlabeledConfigurations}) by the evident [[action]] of the [[symmetric group]] $Sym(n)$ via [[permutation]] of the [[ordering]] of the points. This is the space of unordered and unlabeled configurations of $n$ points\_ in $X$. We write \begin{equation} Conf(X) \;\coloneqq\; \underset{n \in \mathbb{N}}{\sqcup} Conf_n\big( X\big) \label{UnorderedUnlabeledConfigurationSpace}\end{equation} for the unordered unlabeled configuration space of any [[finite number]] of points, being the [[disjoint union]] of these spaces \eqref{UnorderedUnlabelednPointConfigurationSpaces} over all [[natural numbers]] $n$. \end{defn} \begin{remark} \label{MonoidStructureAndItsGroupCompletion}\hypertarget{MonoidStructureAndItsGroupCompletion}{} \textbf{([[monoid]]-[[mathematical structure|structure]] on [[configuration space of points]])} For $X = \mathbb{R}^D$ a [[Euclidean spaces]] the configuration space of points $Conf\big( \mathbb{R}^D \big)$ \eqref{UnorderedUnlabeledConfigurationSpace} carriesthe [[mathematical structure|structure]] of a [[topological monoid]] with product operation being the [[disjoint union]] of point configurations, after a suitable shrinking to put them next to each other (\hyperlink{Segal73}{Segal 73, p. 1-2}). For emphasis, we write $B_{{}_{\sqcup}\!} Conf(\mathbb{R}^D)$ for the [[delooping]] (``[[classifying space]]'') with respect to this [[topological monoid]]-[[structure]]. The corresponding [[based loop space]] is then the [[group completion]] of the configuration space, with respect to disjoint union of points: \begin{equation} Conf \big( \mathbb{R}^D \big) \overset{\color{blue}\text{group completion}}{\longrightarrow} \Omega B_{{}_{\sqcup}\!} Conf(\mathbb{R}^D) \,. \label{GroupCompletionOfConfigurationSpaceMonoid}\end{equation} \end{remark} \begin{remark} \label{}\hypertarget{}{} The configuration space of unordered unlabeled configurations of $n$ points (Def. \ref{OrderedUnlabeledConfigurations}) is naturally a [[topological subspace]] of the [[space of finite subsets]] of [[cardinality]] $\leq n$ \begin{equation} Conf_n(X) \hookrightarrow \exp^n(X) \label{InjectionOfUnorderedConfigurationSpaceOfPoints}\end{equation} \end{remark} \begin{prop} \label{UnorderedConfigurationSpaceInSpaceOfFiniteSubsets}\hypertarget{UnorderedConfigurationSpaceInSpaceOfFiniteSubsets}{} Let $X$ be an [[inhabited set|non-empty]] [[regular topological space]] and $n \geq 2 \in \mathbb{N}$. Then the injection \eqref{InjectionOfUnorderedConfigurationSpaceOfPoints} \begin{equation} Conf_n(X) \hookrightarrow \exp^n(X)/\exp^{n-1}(X) \label{UnorderedConfigurationSpaceOpenSubsetInQuotientOfSpacesOfFiniteSubsets}\end{equation} of the [[unordered configuration space of n points]] of $X$ (Def. \ref{OrderedUnlabeledConfigurations}) into the [[quotient space]] of the [[space of finite subsets]] of cardinality $\leq n$ by its subspace of subsets of cardinality $\leq n-1$ is an [[open subspace]]-inclusion. Moreover, if $X$ is [[compact topological space|compact]], then so is $\exp^n(X)/\exp^{n-1}(X)$ and the inclusion \eqref{UnorderedConfigurationSpaceOpenSubsetInQuotientOfSpacesOfFiniteSubsets} exhibits the [[one-point compactification]] $\big( Conf_n(X) \big)^{+}$ of the configuration space: \begin{displaymath} \big( Conf_n(X) \big)^{+} \;\simeq\; \exp^n(X)/\exp^{n-1}(X) \,. \end{displaymath} \end{prop} (\hyperlink{Handel00}{Handel 00, Prop. 2.23}, see also \hyperlink{FelixTanre10}{Félix-Tanré 10}) \hypertarget{UnorderedLabeledPoints}{}\subsubsection*{{Unordered labeled points}}\label{UnorderedLabeledPoints} \begin{defn} \label{UnorderedLabeledFixedn}\hypertarget{UnorderedLabeledFixedn}{} For $X$ a [[smooth manifold]] and $k \in \mathbb{N}$, the space of \emph{unordered configurations of points in $X$ with labels in $S^k$} is \begin{equation} Conf_n\big(X, S^k \big) \;\coloneqq\; Conf_n\big(X\big) \underset{Sym(n)}{\times} \big( S^k \big)^n \label{UnorderedLabeledFixednCOnfigurationSpace}\end{equation} \end{defn} For $k \in \mathbb{N}$, consider the [[n-sphere|k-sphere]] as a [[pointed topological space]], with the base point regarded as the ``vanishing label''. \begin{defn} \label{UnorderedLabeledConfigurationsVanishingWithVanishingLabel}\hypertarget{UnorderedLabeledConfigurationsVanishingWithVanishingLabel}{} \textbf{(unordered labeled configurations vanishing with vanishing label)} For $X$ a [[smooth manifold]] and $k \in \mathbb{N}$, the space of \emph{unordered configurations of points in $X$ with labels in $S^k$ and vanishing at vanishing label value} is the [[quotient space]] \begin{equation} Conf \big( X, S^k \big) \;\coloneqq\; \Big( \underset{n \in \mathbb{N}}{\sqcup} Conf_n\big(X,S^k \big) \Big)/\sim \label{UnorderedLabeledCOnfigurationSpace}\end{equation} of the [[disjoint union]] of all unordred labeled $n$-point configuration spaces \eqref{UnorderedLabeledFixednCOnfigurationSpace} by the [[equivalence relation]] which regards points with vanishing label as absent. \end{defn} \begin{defn} \label{ConfigurationSpacesOfnPoints}\hypertarget{ConfigurationSpacesOfnPoints}{} \textbf{(unordered labeled configurations of a fixed number of points)} Let $X$ be a [[manifold]], possibly with [[manifold with boundary|boundary]]. For $n \in \mathbb{N}$, the \emph{\textbf{configuration space of $n$ unordered points} in $X$ disappearing at the boundary} is the [[topological space]] \begin{displaymath} \mathrm{Conf}_{n}(X) \;\coloneqq\; \Big( \big( X^n \setminus \mathbf{\Delta}_X^n \big) / \partial(X^n) \Big) /\Sigma(n) \,, \end{displaymath} where $\mathbf{\Delta}_X^n : = \{(x^i) \in X^n | \underset{i,j}{\exists} (x^i = x^j) \}$ is the [[fat diagonal]] in $X^n$ and where $\Sigma(n)$ denotes the evident [[action]] of the [[symmetric group]] by [[permutation]] of factors of $X$ inside $X^n$. More generally, let $Y$ be another [[manifold]], possibly with [[manifold with boundary|boundary]]. For $n \in \mathbb{N}$, the \emph{\textbf{configuration space of $n$ points} in $X \times Y$ vanishing at the boundary and distinct as points in $X$} is the [[topological space]] \begin{displaymath} \mathrm{Conf}_{n}(X,Y) \;\coloneqq\; \Big( \big( ( X^n \setminus \mathbf{\Delta}_X^n ) \times Y^n \big) /\Sigma(n) \Big) / \partial(X^n \times Y^n) \end{displaymath} where now $\Sigma(n)$ denotes the evident [[action]] of the [[symmetric group]] by [[permutation]] of factors of $X \times Y$ inside $X^n \times Y^n \simeq (X \times Y)^n$. This more general definition reduces to the previous case for $Y = \ast \coloneqq \mathbb{R}^0$ being the point: \begin{displaymath} \mathrm{Conf}_n(X) \;=\; \mathrm{Conf}_n(X,\ast) \,. \end{displaymath} Finally the \emph{\textbf{configuration space of an arbitrary number of points} in $X \times Y$ vanishing at the boundary and distinct already as points of $X$} is the [[quotient topological space]] of the [[disjoint union space]] \begin{displaymath} Conf\left( X, Y\right) \;\coloneqq\; \left( \underset{n \in \mathbb{n}}{\sqcup} \big( ( X^n \setminus \mathbf{\Delta}_X^n ) \times Y^k \big) /\Sigma(n) \right)/\sim \end{displaymath} by the [[equivalence relation]] $\sim$ given by \begin{displaymath} \big( (x_1, y_1), \cdots, (x_{n-1}, y_{n-1}), (x_n, y_n) \big) \;\sim\; \big( (x_1, y_1), \cdots, (x_{n-1}, y_{n-1}) \big) \;\;\;\; \Leftrightarrow \;\;\;\; (x_n, y_n) \in \partial (X \times Y) \,. \end{displaymath} This is naturally a [[filtered topological space]] with filter stages \begin{displaymath} Conf_{\leq n}\left( X, Y\right) \;\coloneqq\; \left( \underset{k \in \{1, \cdots, n\}}{\sqcup} \big( ( X^k \setminus \mathbf{\Delta}_X^k ) \times Y^k \big) /\Sigma(k) \right)/\sim \,. \end{displaymath} The corresponding [[quotient topological spaces]] of the filter stages reproduces the above configuration spaces of a fixed number of points: \begin{displaymath} Conf_n(X,Y) \;\simeq\; Conf_{\leq n}(X,Y) / Conf_{\leq (n-1)}(X,Y) \,. \end{displaymath} \end{defn} \begin{remark} \label{}\hypertarget{}{} \textbf{(comparison to notation in the literature)} The above Def. \ref{ConfigurationSpacesOfnPoints} is less general but possibly more suggestive than what is considered for instance in \hyperlink{Boedigheimer87}{Bödigheimer 87}. Concretely, we have the following translations of notation: \begin{displaymath} \itexarray{ \text{ here: } && \itexarray{ \text{ Segal 73,} \\ \text{ Snaith 74}: } && \text{ Bödigheimer 87: } \\ \\ Conf(\mathbb{R}^d,Y) &=& C_d( Y/\partial Y ) &=& C( \mathbb{R}^d, \emptyset; Y ) \\ \mathrm{Conf}_n\left( \mathbb{R}^d \right) & = & F_n C_d( S^0 ) / F_{n-1} C_d( S^0 ) & = & D_n\left( \mathbb{R}^d, \emptyset; S^0 \right) \\ \mathrm{Conf}_n\left( \mathbb{R}^d, Y \right) & = & F_n C_d( Y/\partial Y ) / F_{n-1} C_d( Y/\partial Y ) & = & D_n\left( \mathbb{R}^d, \emptyset; Y/\partial Y \right) \\ \mathrm{Conf}_n( X ) && &=& D_n\left( X, \partial X; S^0 \right) \\ \mathrm{Conf}_n( X, Y ) && &=& D_n\left( X, \partial X; Y/\partial Y \right) } \end{displaymath} Notice here that when $Y$ happens to have [[empty space|empty]] [[boundary]], $\partial Y = \emptyset$, then the [[pushout]] \begin{displaymath} X / \partial Y \coloneqq Y \underset{\partial Y}{\sqcup} \ast \end{displaymath} is $Y$ with a \href{pointed+topological+space#ForgettingAndAdjoiningBasepoints}{disjoint basepoint attached}. Notably for $Y =\ast$ the [[point space]], we have that \begin{displaymath} \ast/\partial \ast = S^0 \end{displaymath} is the [[0-sphere]]. \end{remark} A slight variation of the definition is sometimes useful: \begin{defn} \label{ConfigurationSpaceOfDisks}\hypertarget{ConfigurationSpaceOfDisks}{} \textbf{(configuration space of $dim(X)$-disks)} In the situation of Def. \ref{ConfigurationSpaceOfParticleswithLabels}, with $X$ a [[manifold]] of [[dimension]] $dim(X) \in \mathbb{N}$ \begin{displaymath} DiskConf(X,A) \longrightarrow Conf(X,A) \end{displaymath} be, on the left, the labeled configuration space of joint [[embedding of smooth manifolds|embeddings]] of [[tuples]] \begin{displaymath} \left( D^{dim(X)} \overset{ \iota_i }{\hookrightarrow} X \right) \end{displaymath} of $dim(X)$-dimensional disks/[[closed balls]] into $X$, with identifications as in Def. \ref{ConfigurationSpaceOfParticleswithLabels} (in particular the disks centered at the basepoint are quotiented out) and with the comparison map sending each disk to its center. This map is evidently a [[deformation retraction]] hence in particular a [[homotopy equivalence]]. \end{defn} \hypertarget{properties}{}\subsection*{{Properties}}\label{properties} \hypertarget{OrderedUnlabeledConfigurationsFromUnorderedLabeledConfigurations}{}\subsubsection*{{Ordered unlabeled configurations from unordered labeled configurations}}\label{OrderedUnlabeledConfigurationsFromUnorderedLabeledConfigurations} \begin{quote}% under construction \end{quote} (\ldots{}) (\ldots{}) \hypertarget{cohomotopy_charge_map}{}\subsubsection*{{Cohomotopy charge map}}\label{cohomotopy_charge_map} The \emph{Cohomotopy charge map} is the [[function]] that assigns to a [[configuration space of points|configuration of points]] their total [[charge]] as measured in [[Cohomotopy]]-[[generalized cohomology|cohomology theory]]. This is alternatively known as the ``electric field map'' (\hyperlink{Salvatore01}{Salvatore 01} following \hyperlink{Segal73}{Segal 73, Section 1}, see also \hyperlink{Knudsen18}{Knudsen 18, p. 49}) or the ``scanning map'' (\hyperlink{Kallel98}{Kallel 98}). For $D \in \mathbb{N}$ the \emph{Cohomotopy charge map} is the [[continuous function]] \begin{equation} Conf\big( \mathbb{R}^D \big) \overset{cc}{\longrightarrow} \mathbf{\pi}^D \Big( \big( \mathbb{R}^D \big)^{cpt} \Big) = Maps^{\ast/\!}\Big( \big(\mathbb{R}^D\big)^{cpt} , S^D\big) = \Omega^{D} S^D \label{CohomotopyChargeMapOnEuclideanSpace}\end{equation} from the [[configuration space of points]] in the [[Euclidean space]] $\mathbb{R}^D$ to the $D$-[[Cohomotopy]] [[cocycle space]] [[vanishing at infinity]] on the [[Euclidean space]], which is equivalently the [[space of maps|space of pointed maps]] from the [[one-point compactification]] $S^D \simeq \big( \mathbb{R}^D \big)$ to itself, and hence equivalently the $D$-fold [[iterated based loop space]] of the [[n-sphere|D-sphere]]), which sends a configuration of points in $\mathbb{R}^D$, each regarded as carrying unit [[charge]] to their total [[charge]] as measured in [[Cohomotopy]]-[[generalized cohomology|cohomology theory]] (\hyperlink{Segal73}{Segal 73, Section 3}). The construction has evident generalizations to other manifolds than just Euclidean spaces, to spaces of labeled configurations and to [[equivariant Cohomotopy]]. The following graphics illustrates the Cohomotopy charge map on [[G-space]] [[tori]] for $G = \mathbb{Z}_2$ with values in $\mathbb{Z}_2$-[[equivariant Cohomotopy]]: \begin{quote}% graphics grabbed from \href{Cohomotpy+charge+map#SatiSchreiber19}{SS 19} \end{quote} \hypertarget{LoopSpacesOfSuspensions}{}\paragraph*{{Relation to iterated loop spaces of iterated suspensions}}\label{LoopSpacesOfSuspensions} In some situations the [[Cohomotopy charge map]] is a [[weak homotopy equivalence]] and hence exhibits, for all purposes of [[homotopy theory]], the [[Cohomotopy]] [[cocycle space]] of Cohomotopy charges as an equivalent reflection of the [[configuration space of points]]: \begin{prop} \label{GroupCompletionOfConfigurationSpaceIsIteratedBasedLoopSpace}\hypertarget{GroupCompletionOfConfigurationSpaceIsIteratedBasedLoopSpace}{} \textbf{([[group completion]] on [[configuration space of points]] is [[iterated based loop space]])} The [[Cohomotopy charge map]] \eqref{CohomotopyChargeMapOnEuclideanSpace} \begin{displaymath} Conf \big( \mathbb{R}^D \big) \overset{ cc }{\longrightarrow} \Omega^D S^D \end{displaymath} from the full unordered and unlabeled configuration space \eqref{UnorderedUnlabeledConfigurationSpace} of [[Euclidean space]] $\mathbb{R}^D$ to the $D$-fold [[iterated based loop space]] of the [[n-sphere|D-sphere]], exhibits the [[group completion]] \eqref{GroupCompletionOfConfigurationSpaceMonoid} of the configuration space monoid \begin{displaymath} \Omega B_{{}_{\sqcup}\!} Conf \big( \mathbb{R}^D \big) \overset{ \simeq }{\longrightarrow} \Omega^D S^D \end{displaymath} \end{prop} (\hyperlink{Segal73}{Segal 73, Theorem 1}) \begin{prop} \label{CohomotopyChargeMapIsEquivalenceOnSPhereLabeledConfihgurationSpace}\hypertarget{CohomotopyChargeMapIsEquivalenceOnSPhereLabeledConfihgurationSpace}{} \textbf{([[Cohomotopy charge map]] is [[weak homotopy equivalence]] on sphere-labeled [[configuration space of points]])} For $D, k \in \mathbb{N}$ with $k \geq 1$, the [[Cohomotopy charge map]] \eqref{CohomotopyChargeMapOnEuclideanSpace} \begin{displaymath} Conf \big( \mathbb{R}^D, S^k \big) \underoverset{\simeq}{\;\;cc\;\;}{\longrightarrow} \Omega^D S^{D + k} \;\simeq\; \mathbf{\pi}^{D+ k}\Big( \big( \mathbb{R}^{D}\big)^{cpt} \Big) \end{displaymath} is a [[weak homotopy equivalence]] \begin{itemize}% \item from the configuration space \eqref{UnorderedLabeledCOnfigurationSpace} of unordered points with labels in $S^k$ and vanishing at the base point of the label space \item to the $D$-fold [[iterated loop space]] of the [[n-sphere|D+k-sphere]] \end{itemize} hence equivalently \begin{itemize}% \item to the [[cocycle space]] of [[Cohomotopy]] [[generalized cohomology theory|cohomology theory]] in degree $D + k$ [[vanishing at infinity]] on [[Euclidean space]] of [[dimension]] $D$. \end{itemize} \end{prop} (\hyperlink{Segal73}{Segal 73, Theorem 3}) This statement generalizes to [[equivariant homotopy theory]], with equivariant configurations carrying charge in [[equivariant Cohomotopy]]: Let $G$ be a [[finite group]] and $V \in RO(G)$ an [[orthogonal group|orthogonal]] $G$-[[linear representation]], with its induced [[pointed topological space|pointed]] [[topological G-spaces]]: \begin{enumerate}% \item the corresponding [[representation sphere]] $S^V \in G TopSpaces$, \item the corresponding [[Euclidean G-space]] $\mathbb{R}^V \in G TopSpaces$. \end{enumerate} For $X \in G TopSpaces$ any [[pointed topological space|pointed]] [[topological G-space]], consider \begin{enumerate}% \item the equivariant $V$-[[suspension]], given by the [[smash product]] with the $V$-[[representation sphere]]: $\Sigma^V X \;\coloneqq\; X \wedge S^V \;\in G TopSpaces\;$ \item the equivariant $V$-[[iterated based loop space]], given by the $G$-[[fixed point subspace]] inside the [[space of maps]] out of the [[representation sphere]]: $\Omega^V X \;\coloneqq\; Maps^{\ast/}\big( S^V, X\big)^G$. \end{enumerate} \begin{defn} \label{EquivariantUnorderedLabeledConfigurationsVanishingWithVanishingLabel}\hypertarget{EquivariantUnorderedLabeledConfigurationsVanishingWithVanishingLabel}{} \textbf{(equivariant unordered labeled configurations vanishing with vanishing label)} Write \begin{displaymath} Conf\big( \mathbb{R}^V , X \big)^G \;\hookrightarrow\; Conf\big( \mathbb{R}^V , X \big) \end{displaymath} for the $G$-[[fixed point subspace]] in the unordered $X$-labelled configuration space of points (Def. \ref{UnorderedLabeledConfigurationsVanishingWithVanishingLabel}), with respect to the [[diagonal action]] on $\mathbb{R}^V \times X$. \end{defn} \begin{prop} \label{EquivariantCohomotopyChargeMapEquivalence}\hypertarget{EquivariantCohomotopyChargeMapEquivalence}{} \textbf{([[Cohomotopy charge map]]-equivalence for configurations on [[Euclidean G-spaces]])} Let \begin{enumerate}% \item $G$ be a [[finite group]], \item $V$ an [[orthogonal group|orthogonal]] $G$-[[linear representation]] \item $X$ a [[topological G-space]] \end{enumerate} If $X$ is $G$-connected, in that for all [[subgroups]] $H \subset G$ the $H$-[[fixed point subspace]] $X^H$ is a [[connected topological space]], then the [[Cohomotopy charge map]] \begin{displaymath} Conf \big( \mathbb{R}^V, X \big) \underoverset{\simeq}{\;cc\;}{\longrightarrow} \Omega^V \Sigma^V X \phantom{AAA} \text{if X is G-connected} \end{displaymath} from the equivariant un-ordered $X$-labeled configuration space of points (Def. \ref{EquivariantUnorderedLabeledConfigurationsVanishingWithVanishingLabel}) in the corresponding [[Euclidean G-space]] to the based $V$-loop space of the $V$-suspension of $X$, is a [[weak homotopy equivalence]]. If $X$ is not necessarily $G$-connected, then this still holds for the [[group completion]] of the configuration space, under disjoint union of configurations \begin{displaymath} \Omega B_{{}_{\sqcup}\!} Conf \big( \mathbb{R}^V, X \big) \underoverset{\simeq}{\;cc\;}{\longrightarrow} \Omega^{V+1} \Sigma^{V+1} X \,. \end{displaymath} \end{prop} (\hyperlink{RourkeSanderson00}{Rourke-Sanderson 00, Theorem 1, Theorem 2}) More generally: \begin{prop} \label{ScanningMapEquivalenceOverCartesianSpace}\hypertarget{ScanningMapEquivalenceOverCartesianSpace}{} \textbf{([[iterated loop spaces]] equivalent to [[configuration spaces of points]])} For \begin{enumerate}% \item $d \in \mathbb{N}$, $d \geq 1$ a [[natural number]] with $\mathbb{R}^d$ denoting the [[Cartesian space]]/[[Euclidean space]] of that [[dimension]], \item $Y$ a [[manifold]], with [[inhabited set|non-empty]] [[manifold with boundary|boundary]] so that $Y / \partial Y$ is [[connected topological space|connected]], \end{enumerate} the [[Cohomotopy charge map]] constitutes a [[homotopy equivalence]] \begin{displaymath} Conf\left( \mathbb{R}^D, Y \right) \overset{cc}{\longrightarrow} \Omega^D \Sigma^D (Y/\partial Y) \end{displaymath} between \begin{enumerate}% \item the configuration space of arbitrary points in $\mathbb{R}^d \times Y$ vanishing at the boundary (Def. \ref{ConfigurationSpacesOfnPoints}) \item the [[iterated loop space|d-fold loop space]] of the $d$-fold [[reduced suspension]] of the [[quotient space]] $Y / \partial Y$ (regarded as a [[pointed topological space]] with basepoint $[\partial Y]$). \end{enumerate} In particular when $Y = \mathbb{D}^k$ is the [[closed ball]] of [[dimension]] $k \geq 1$ this gives a [[homotopy equivalence]] \begin{displaymath} Conf\left( \mathbb{R}^D, \mathbb{D}^k \right) \overset{cc}{\longrightarrow} \Omega^D S^{ D + k } \end{displaymath} with the [[iterated loop space|d-fold loop space]] of the [[n-sphere|(d+k)-sphere]]. \end{prop} (\hyperlink{May72}{May 72, Theorem 2.7}, \hyperlink{Segal73}{Segal 73, Theorem 3}, see \hyperlink{Boedigheimer87}{Bödigheimer 87, Example 13}) \begin{prop} \label{StableSplittingOfMappingSpacesOutOfEuclideanSpace}\hypertarget{StableSplittingOfMappingSpacesOutOfEuclideanSpace}{} \textbf{([[stable splitting of mapping spaces]] out of [[Euclidean space]]/[[n-spheres]])} For \begin{enumerate}% \item $d \in \mathbb{N}$, $d \geq 1$ a [[natural number]] with $\mathbb{R}^d$ denoting the [[Cartesian space]]/[[Euclidean space]] of that [[dimension]], \item $Y$ a [[manifold]], with [[inhabited set|non-empty]] [[manifold with boundary|boundary]] so that $Y / \partial Y$ is [[connected topological space|connected]], \end{enumerate} there is a [[stable weak homotopy equivalence]] \begin{displaymath} \Sigma^\infty Conf(\mathbb{R}^d, Y) \overset{\simeq}{\longrightarrow} \underset{n \in \mathbb{N}}{\oplus} \Sigma^\infty Conf_n(\mathbb{R}^d, Y) \end{displaymath} between \begin{enumerate}% \item the [[suspension spectrum]] of the [[configuration space of points|configuration space]] of an arbitrary number of points in $\mathbb{R}^d \times Y$ vanishing at the boundary and distinct already as points of $\mathbb{R}^d$ (Def. \ref{ConfigurationSpacesOfnPoints}) \item the [[direct sum]] (hence: [[wedge sum]]) of [[suspension spectra]] of the [[configuration space of points|configuration spaces]] of a fixed number of points in $\mathbb{R}^d \times Y$, vanishing at the boundary and distinct already as points in $\mathbb{R}^d$ (also Def. \ref{ConfigurationSpacesOfnPoints}). \end{enumerate} Combined with the [[stabilization]] of the [[Cohomotopy charge map]] [[homotopy equivalence]] from Prop. \ref{ScanningMapEquivalenceOverCartesianSpace} this yields a [[stable weak homotopy equivalence]] \begin{displaymath} Maps_{cp}(\mathbb{R}^d, \Sigma^d (Y / \partial Y)) = Maps^{\ast/}( S^d, \Sigma^d (Y / \partial Y)) = \Omega^d \Sigma^d (Y/\partial Y) \underoverset{\Sigma^\infty cc}{\simeq}{\longrightarrow} \Sigma^\infty Conf(\mathbb{R}^d, Y) \overset{\simeq}{\longrightarrow} \underset{n \in \mathbb{N}}{\oplus} \Sigma^\infty Conf_n(\mathbb{R}^d, Y) \end{displaymath} between the latter direct sum and the [[suspension spectrum]] of the [[mapping space]] of pointed [[continuous functions]] from the [[n-sphere|d-sphere]] to the $d$-fold [[reduced suspension]] of $Y / \partial Y$. \end{prop} (\hyperlink{Snaith74}{Snaith 74, theorem 1.1}, \hyperlink{Boedigheimer87}{Bödigheimer 87, Example 2}) In fact by \hyperlink{Boedigheimer87}{Bödigheimer 87, Example 5} this equivalence still holds with $Y$ treated on the same footing as $\mathbb{R}^d$, hence with $Conf_n(\mathbb{R}^d, Y)$ on the right replaced by $Conf_n(\mathbb{R}^d \times Y)$ in the well-adjusted notation of Def. \ref{ConfigurationSpacesOfnPoints}: \begin{displaymath} Maps_{cp}(\mathbb{R}^d, \Sigma^d (Y / \partial Y)) = Maps^{\ast/}( S^d, \Sigma^d (Y / \partial Y)) \overset{\simeq}{\longrightarrow} \underset{n \in \mathbb{N}}{\oplus} \Sigma^\infty Conf_n(\mathbb{R}^d \times Y) \end{displaymath} \hypertarget{relation_to_classifying_space_of_the_symmetric_group}{}\paragraph*{{Relation to classifying space of the symmetric group}}\label{relation_to_classifying_space_of_the_symmetric_group} Let $X= \mathbb{R}^\infty$. Then \begin{itemize}% \item the \emph{unordered} configuration space of $n$ points in $\mathbb{R}^\infty$ is a model for the [[classifying space]] $B \Sigma(n)$ of the [[symmetric group]] $\Sigma(n)$; (e.g. \hyperlink{Boedigheimer87}{Bödigheimer 87, Example 10}) \item the \emph{ordered} configuration space of $n$ points, equipped with the canonical $\Sigma(n)$-[[action]], is a model for the $\Sigma(n)$-[[universal principal bundle]]. \end{itemize} $\,$ \hypertarget{relation_to_james_construction}{}\paragraph*{{Relation to James construction}}\label{relation_to_james_construction} The [[James construction]] of $X$ is [[homotopy equivalence|homotopy equivalent]] to the [[configuration space of points]] $C(\mathbb{R}^1, X)$ of points in the [[real line]] with labels taking values in $X$. (e.g. \hyperlink{Boedigheimer87}{Bödigheimer 87, Example 9}) $\,$ \hypertarget{RelationToTwistedCohomotopy}{}\paragraph*{{In twisted Cohomotopy}}\label{RelationToTwistedCohomotopy} The May-Segal theorem \ref{ScanningMapEquivalenceOverCartesianSpace} generalizes from [[Euclidean space]] to [[closed manifold|closed]] [[smooth manifolds]] if at the same time one passes from plain [[Cohomotopy]] to [[twisted Cohomotopy]], twisted, via the [[J-homomorphism]], by the [[tangent bundle]]: \begin{prop} \label{ScanningMapEquivalenceOverClosedManifold}\hypertarget{ScanningMapEquivalenceOverClosedManifold}{} Let \begin{enumerate}% \item $X^n$ be a [[smooth manifold|smooth]] [[closed manifold]] of [[dimension]] $n$; \item $1 \leq k \in \mathbb{N}$ a [[positive number|positive]] [[natural number]]. \end{enumerate} Then the [[Cohomotopy charge map]] constitutes a [[weak homotopy equivalence]] \begin{displaymath} \underset{ \color{blue} { \phantom{a} \atop \text{ J-twisted Cohomotopy space}} }{ Maps_{{}_{/B O(n)}} \Big( X^n \;,\; S^{ \mathbf{n}_{def} + \mathbf{k}_{\mathrm{triv}} } \!\sslash\! O(n) \Big) } \underoverset {\simeq} { \color{blue} \text{Cohomotopy charge map} } {\longleftarrow} \underset{ \mathclap{ \color{blue} { \phantom{a} \atop { \text{configuration space} \atop \text{of points} } } } }{ Conf \big( X^n, S^k \big) } \end{displaymath} between \begin{enumerate}% \item the [[J-homomorphism|J]]-[[twisted Cohomotopy|twisted (n+k)-Cohomotopy]] space of $X^n$, hence the [[space of sections]] of the $(n + k)$-[[spherical fibration]] over $X$ which is [[associated fiber bundle|associated]] via the [[tangent bundle]] by the [[O(n)]]-[[action]] on $S^{n+k} = S(\mathbb{R}^{n} \times \mathbb{R}^{k+1})$ \item the [[configuration space of points]] on $X^n$ with labels in $S^k$. \end{enumerate} \end{prop} (\hyperlink{Boedigheimer87}{Bödigheimer 87, Prop. 2}, following \hyperlink{McDuff75}{McDuff 75}) \begin{prop} \label{ScanningMapEquivalenceOverClosedFramedManifold}\hypertarget{ScanningMapEquivalenceOverClosedFramedManifold}{} In the special case that the [[closed manifold]] $X^n$ in Prop. \ref{ScanningMapEquivalenceOverClosedManifold} is [[parallelizable manifold|parallelizable]], hence that its [[tangent bundle]] is [[trivial bundle|trivializable]], the statement of Prop. \ref{ScanningMapEquivalenceOverClosedManifold} reduces to this: Let \begin{enumerate}% \item $X^n$ be a [[parallelizable manifold|parallelizable]] [[closed manifold]] of [[dimension]] $n$; \item $1 \leq k \in \mathbb{N}$ a [[positive number|positive]] [[natural number]]. \end{enumerate} Then the [[Cohomotopy charge map]] constitutes a [[weak homotopy equivalence]] \begin{displaymath} \underset{ \color{blue} { \phantom{a} \atop \text{ Cohomotopy space}} }{ Maps \Big( X^n \;,\; S^{ n + k } \Big) } \underoverset {\simeq} { \color{blue} \text{Cohomotopy charge map} } {\longleftarrow} \underset{ \mathclap{ \color{blue} { \phantom{a} \atop { \text{configuration space} \atop \text{of points} } } } }{ Conf \big( X^n, S^k \big) } \end{displaymath} between \begin{enumerate}% \item $(n+k)$-[[Cohomotopy]] space of $X^n$, hence the [[space of maps]] from $X$ to the [[n-sphere|(n+k)-sphere]] \item the [[configuration space of points]] on $X^n$ with labels in $S^k$. \end{enumerate} \end{prop} \hypertarget{action_by_little_disk_operad_and_by_goodwillie_derivatives}{}\subsubsection*{{Action by little $n$-disk operad and by Goodwillie derivatives}}\label{action_by_little_disk_operad_and_by_goodwillie_derivatives} Under some conditions and with suitable degrees/shifts, configuration spaces of points canonically have the [[structure]] of [[algebras over an operad]] over the [[little n-disk operad]] and the [[Goodwillie derivatives of the identitity functor]]. For more see \href{Goodwillie+derivatives+of+the+identity+functor#Properties}{there} $\backslash$linebreak \hypertarget{HomologyAndStabilization}{}\subsubsection*{{Homology and stabilization in homology}}\label{HomologyAndStabilization} Let $X$ be a [[topological space]] which is the [[interior]] of a [[compact topological space|compact]] [[manifold with boundary]] $\overline{X}$. We may think of the [[boundary]] $\partial \overline X$ as consisting of the ``points at infinity'' in $X$. In particular, there are then inclusion maps \begin{equation} Conf_n \big( X \big) \overset{i_n}{\longrightarrow} Conf_{n+1} \big( X \big) \label{InclusionOfUnorderedConfigurationSpaces}\end{equation} of the unordered configuration space of $n$ points in $X$ (Def. \ref{UnorderedUnlabeledConfigurations}) into that of $n + 1$ points, formalizing the idea of ``adding a point at infinity'' to a configuration. More formally, these maps are given by pushing configuration points away from the boundary a little and then adding a new point near to a point on the boundary of $X$. (\hyperlink{RandalWilliams13}{Randal-Williams 13, Section 4}) The [[homotopy class]] of these maps depends (just) on the [[connected component]] of the [[boundary]] $\partial \overline{X}$ at which one chooses to bring in the new point. But for any choice, they have the following effect on [[cycles]] in [[ordinary homology]]: \begin{prop} \label{HomologicalStabilizationForUnorderedConfigurationSpaces}\hypertarget{HomologicalStabilizationForUnorderedConfigurationSpaces}{} \textbf{(homological stabilization for unordered configuration spaces)} Let $X$ be \begin{itemize}% \item a [[connected topological space|connected]] [[smooth manifold]] \item which is the [[interior]] of a [[compact topological space|compact]] [[manifold with boundary]] \item of [[dimension]] $dim(X) \geq 2$. \end{itemize} Then for all $n \in \mathbb{N}$ the inclusion [[maps]] \eqref{InclusionOfUnorderedConfigurationSpaces} are such that on [[ordinary homology]] with [[integer]] [[coefficients]] these maps induce [[split monomorphisms]] in all degrees, \begin{displaymath} H_\bullet \big( Conf_n(X) , \mathbb{Z} \big) \overset{ H_\bullet( i_n, \mathbb{Z} ) }{\hookrightarrow} H_\bullet \big( Conf_{n+1}(X) , \mathbb{Z} \big) \end{displaymath} and in degrees $\leq n/2$ these are even [[isomorphisms]] \begin{displaymath} H_p \big( Conf_n(X) , \mathbb{Z} \big) \underoverset{\simeq}{ H_p( i_n, \mathbb{Z} ) }{\hookrightarrow} H_p \big( Conf_{n+1}(X) , \mathbb{Z} \big) \phantom{AAAA} \text{for} \; p \leq n/2 \,. \end{displaymath} Finally, for [[ordinary homology]] with [[rational number|rational]] [[coefficients]], these maps induce [[isomorphisms]] all the way up to degree $n$: \begin{displaymath} H_p \big( Conf_n(X) , \mathbb{Q} \big) \underoverset{\simeq}{ H_p( i_n, \mathbb{Q} ) }{\hookrightarrow} H_p \big( Conf_{n+1}(X) , \mathbb{Q} \big) \phantom{AAAA} \text{for} \; p \leq n \,. \end{displaymath} \end{prop} (\hyperlink{RandalWilliams13}{Randal-Williams 13, Theorem A and Threorem B}) $\backslash$linebreak \hypertarget{RationalHomotopyType}{}\subsubsection*{{Rational homotopy type}}\label{RationalHomotopyType} We discuss aspects of the [[rational homotopy type]] of configuration spaces of points. See also at \emph{[[graph complex]]}. \hypertarget{Cohomology}{}\paragraph*{{Rational cohomology}}\label{Cohomology} \begin{prop} \label{RealCohomologyOfConfigurationSpaceOfOrderedPointsInEuclideanSpace}\hypertarget{RealCohomologyOfConfigurationSpaceOfOrderedPointsInEuclideanSpace}{} \textbf{([[real cohomology]] of configuration spaces of ordered points in [[Euclidean space]])} The [[real cohomology|real]] [[cohomology ring]] of the configuration spaces $\underset{{}^{\{1,\cdots,n\}}}{Conf}\big( \mathbb{R}^D\big)$ (Def. \ref{OrderedUnlabeledConfigurations}) of $n$ ordered unlabeled points in [[Euclidean space]] $\mathbb{R}^D$ is [[generators and relations|generated]] by elements in degree $D-1$ \begin{displaymath} \omega_{i j} \;\; \in H^2 \Big( \underset{ {}^{\{1, \cdots, n\}} }{ Conf } \big( \mathbb{R}^D \big), \mathbb{R} \Big) \end{displaymath} for $i, j \in \{1, \cdots, n\}$ subject to these three [[generators and relations|relations]]: \begin{enumerate}% \item \textbf{(anti-)symmetry)} \begin{displaymath} \omega_{i j} = (-1)^D \omega_{j i} \end{displaymath} \item \textbf{nilpotency} \begin{displaymath} \omega_{i j} \wedge \omega_{i j} \;=\; 0 \end{displaymath} \item \textbf{3-term relation} \begin{displaymath} \omega_{i j} \wedge \omega_{j k} + \omega_{j k} \wedge \omega_{k i} + \omega_{k i} \wedge \omega_{i j} = 0 \end{displaymath} \end{enumerate} Hence: \begin{equation} H^\bullet \Big( \underset{ {}^{\{1,\cdots,n\}} }{Conf} \big( \mathbb{R}^D \big), \mathbb{R} \Big) \;\simeq\; \mathbb{R}\Big[ \big\{\omega_{i j} \big\}_{i, j \in \{1, \cdots, n\}} \Big] \Big/ \left( \itexarray{ \omega_{i j} = (-1)^D \omega_{j i} \\ \omega_{i j} \wedge \omega_{i j} = 0 \\ \omega_{i j} \wedge \omega_{j k} + \omega_{j k} \omega_{k i} + \omega_{k i} \wedge \omega_{i j} = 0 } \;\; \text{for}\; i,j \in \{1, \cdots, n\} \right) \label{RealCohomologyOfUnorderedConfigurationSpaceInEuclideanSpace}\end{equation} \end{prop} This is due to \hyperlink{Cohen76}{Cohen 76}, following \hyperlink{Arnold69}{Arnold 69}, \hyperlink{Cohen73}{Cohen 73}. See also \hyperlink{FelixTanre03}{Félix-Tanré 03, Section 2} \hyperlink{LambrechtsTourtchine09}{Lambrechts-Tourtchine 09, Section 3}. See also at \emph{[[Fulton-MacPherson compactification]]} the section \emph{\href{Fulton-MacPherson+operad#deRhamCohomology}{de Rham cohomology}}. \begin{remark} \label{RealCohomologyOfConfigurationSpaceInTermsOfGraphCohomology}\hypertarget{RealCohomologyOfConfigurationSpaceInTermsOfGraphCohomology}{} \textbf{([[real cohomology]] of the configuration space in terms of [[graph cohomology]])} In the [[graph complex]]-model for the [[rational homotopy type]] of the ordered unlabled [[configuration space of points]] $\underset{{}^{\{1,\cdots,n\}}}{Conf}\big( \mathbb{R}^D\big)$ the three relations in Prop. \ref{RealCohomologyOfConfigurationSpaceOfOrderedPointsInEuclideanSpace} are incarnated as follows: \begin{enumerate}% \item a graph changes sign when one of its edges is reversed (\href{graph+complex#SignRulesForGraphs}{this Def.}) \item a graph with [[parallel edges]] is a vanishing graph (\href{graph+complex#VanishingGraphs}{this Def.}) \item the graph coboundary of a single trivalent internal vertex (\href{graph+complex#ThreeTermRelation}{this Example}). \end{enumerate} \end{remark} $\backslash$linebreak \hypertarget{RationalHomotopyGroups}{}\paragraph*{{Rational homotopy and Whitehead products}}\label{RationalHomotopyGroups} Write again \begin{displaymath} Conf_n\big( \mathbb{R}^D \big) \;\coloneqq\; \big( \mathbb{R}^D \big)^n \setminus FatDiag \end{displaymath} for the configuration space of $n$ ordered points in [[Euclidean space]]. \begin{prop} \label{RationalHomotopyOfConfigurationSpaceOfOrderedPointsInEuclideanSpace}\hypertarget{RationalHomotopyOfConfigurationSpaceOfOrderedPointsInEuclideanSpace}{} The [[Whitehead product]] [[super Lie algebra]] of [[rationalization|rationalized]] [[homotopy groups]] \begin{displaymath} L^n \;\coloneqq\; \pi_{\bullet+1}\Big( Conf_n\big( \mathbb{R}^D \big) \Big) \otimes_{\mathbb{Z}} \mathbb{Q} \end{displaymath} is [[generators and relations|generated]] from elements \begin{displaymath} \omega^{i j} \;\in\; \pi_2 \Big( Conf_n\big( \mathbb{R}^D \big) \Big) \otimes_{\mathbb{Z}} \mathbb{Q} \phantom{AAA} i \neq j \in \{1, \cdots, n\} \,, \end{displaymath} subject to the following [[generators and relations|relations]]: \begin{enumerate}% \item $\omega^{i j} = (-1)^D \omega^{j i}$ \item $\big[ \omega^{i j}, \omega^{k l} \big]$ $\;\;\;$ if $i,j,k,l$ are pairwise distinct; \item $\big[ \omega^{i j}, \omega^{j k} + \omega^{k i} \big] = 0$. \end{enumerate} \end{prop} This is due to \hyperlink{Kohno02}{Kohno 02}. See also \hyperlink{LambrechtsTourtchine09}{Lambrechts-Tourtchine 09, Section 3}. $\backslash$linebreak $\backslash$linebreak \hypertarget{OccurrencesAndApplications}{}\subsection*{{Occurrences and Applications}}\label{OccurrencesAndApplications} \hypertarget{compactification}{}\subsubsection*{{Compactification}}\label{compactification} The [[Fulton-MacPherson compactification]] of configuration spaces of points in $\mathbb{R}^d$ serves to exhibit them as models for the [[little n-disk operad]]. \hypertarget{stable_splitting_of_mapping_spaces}{}\subsubsection*{{Stable splitting of mapping spaces}}\label{stable_splitting_of_mapping_spaces} The [[stable splitting of mapping spaces]] says that [[suspension spectra]] of suitable [[mapping spaces]] are equivalently [[wedge sums]] of [[suspension spectra]] of configuration spaces of points. \hypertarget{correlators_as_differential_forms_on_configuration_spaces}{}\subsubsection*{{Correlators as differential forms on configuration spaces}}\label{correlators_as_differential_forms_on_configuration_spaces} In [[Euclidean field theory]] the [[correlators]] are often regarded as [[distributions of several variables]] with [[singularities]] on the [[fat diagonal]]. Hence they become [[non-singular distributions]] after [[restriction of distributions]] to the corresponding configuration space of points. For more on this see at \emph{[[correlators as differential forms on configuration spaces of points]]}. \hypertarget{related_concepts}{}\subsection*{{Related concepts}}\label{related_concepts} \begin{itemize}% \item [[Hilbert scheme]] \end{itemize} \hypertarget{references}{}\subsection*{{References}}\label{references} \hypertarget{general}{}\subsubsection*{{General}}\label{general} General accounts: \begin{itemize}% \item [[Edward Fadell]], [[Lee Neuwirth]], \emph{Configuration spaces}, Math. Scand. \textbf{10} (1962) 111-118, \href{http://www.ams.org/mathscinet-getitem?mr=141126}{MR141126}, \href{http://www.mscand.dk/article.php?id=1623}{pdf} \item [[Edward Fadell]], [[Sufian Husseini]], \emph{Geometry and topology of configuration spaces}, Springer Monographs in Mathematics (2001), \href{http://www.ams.org/mathscinet-getitem?mr=2002k:55038}{MR2002k:55038}, xvi+313 \item [[Craig Westerland]], \emph{Configuration spaces in geometry and topology}, 2011 (\href{https://www.austms.org.au/Publ/Gazette/2011/Nov11/TechPaperWesterland.pdf}{pdf}) (in [[geometry]] and [[topology]]) \item [[Ben Knudsen]], \emph{Configuration spaces in algebraic topology} (\href{https://arxiv.org/abs/1803.11165}{arXiv:1803.11165}) (in [[algebraic topology]]) \end{itemize} In relation to the [[space of finite subsets]]: \begin{itemize}% \item David Handel, \emph{Some Homotopy Properties of Spaces of Finite Subsets of Topological Spaces}, Houston Journal of Mathematics, Electronic Edition Vol. 26, No. 4, 2000 (\href{https://www.math.uh.edu/~hjm/Vol26-4.html}{hjm:Vol26-4}) \item [[Yves Félix]], [[Daniel Tanré]] \emph{Rational homotopy of symmetric products and Spaces of finite subsets}, Contemp. Math 519 (2010): 77-92 (\href{http://tanre.org/Pro/Articles_files/SpnFiniteDef.pdf}{pdf}) \end{itemize} The [[algebra over an operad|algebra]]-[[structure]] of configuration spaces over [[little n-disk operads]]/[[Fulton-MacPherson operads]]: \begin{itemize}% \item [[Martin Markl]], \emph{A compactification of the real configuration space as an operadic completion, J. Algebra 215 (1999), no. 1, 185–204} \end{itemize} \hypertarget{cohomotopy_charge_map_2}{}\subsubsection*{{Cohomotopy charge map}}\label{cohomotopy_charge_map_2} The [[Cohomotopy charge map]] (``electric field map'', ``scanning map'') and hence the relation of configuration spaces to [[Cohomotopy]] goes back to \begin{itemize}% \item [[Peter May]], \emph{The geometry of iterated loop spaces}, Springer 1972 (\href{https://www.math.uchicago.edu/~may/BOOKS/geom_iter.pdf}{pdf}) \item [[Graeme Segal]], \emph{Configuration-spaces and iterated loop-spaces}, Invent. Math. \textbf{21} (1973), 213--221. MR 0331377 (\href{http://dodo.pdmi.ras.ru/~topology/books/segal.pdf}{pdf}) c Generalization of these constructions and results is due to \item [[Dusa McDuff]], \emph{Configuration spaces of positive and negative particles}, Topology Volume 14, Issue 1, March 1975, Pages 91-107 () \item [[Carl-Friedrich Bödigheimer]], \emph{Stable splittings of mapping spaces}, Algebraic topology. Springer 1987. 174-187 (\href{http://www.math.uni-bonn.de/~cfb/PUBLICATIONS/stable-splittings-of-mapping-spaces.pdf}{pdf}, [[BoedigheimerStableSplittings87.pdf:file]]) \item Richard Manthorpe, [[Ulrike Tillmann]], \emph{Tubular configurations: equivariant scanning and splitting}, Journal of the London Mathematical Society, Volume 90, Issue 3 (\href{https://arxiv.org/abs/1307.5669}{arxiv:1307.5669}, \href{https://doi.org/10.1112/jlms/jdu050}{doi:10.1112/jlms/jdu050}) \end{itemize} and generalization to [[equivariant homotopy theory]] is discussed in \begin{itemize}% \item [[Colin Rourke]], [[Brian Sanderson]], \emph{Equivariant Configuration Spaces}, J. London Math. Soc. 62 (2000) 544-552 (\href{https://arxiv.org/abs/math/9712216}{arXiv:math/9712216}) \end{itemize} The relevant construction for the [[group completion]] of the configuration space \begin{itemize}% \item \hyperlink{Segal73}{Segal 73, Theorem 1} \item [[Paolo Salvatore]], \emph{Configuration spaces with summable labels}, In: Aguadé J., Broto C., [[Carles Casacuberta]] (eds.) \emph{Cohomological Methods in Homotopy Theory}. Progress in Mathematics, vol 196. Birkhäuser, Basel, 2001 (\href{https://arxiv.org/abs/math/9907073}{arXiv:math/9907073}) \end{itemize} On the [[homotopy type]] of the [[space of maps|space of]] [[rational functions]] from the [[Riemann sphere]] to itself (related to the [[moduli space of monopoles]] in $\mathbb{R}^3$ and to the [[configuration space of points]] in $\mathbb{R}^2$): \begin{itemize}% \item [[Graeme Segal]], \emph{The topology of spaces of rational functions}, Acta Math. Volume 143 (1979), 39-72 (\href{https://projecteuclid.org/euclid.acta/1485890033}{euclid:1485890033}) \end{itemize} See also \begin{itemize}% \item [[Sadok Kallel]], \emph{Particle Spaces on Manifolds and Generalized Poincaré Dualities} (\href{https://arxiv.org/abs/math/9810067}{arXiv:math/9810067}) \item Shingo Okuyama, Kazuhisa Shimakawa, \emph{Interactions of strings and equivariant homology theories}, (\href{https://arxiv.org/abs/0903.4667}{arXiv:0903.4667}) \end{itemize} For relation to [[instantons]] via [[topological Yang-Mills theory]]: \begin{itemize}% \item [[Michael Atiyah]], [[John David Stuart Jones]], \emph{Topological aspects of Yang-Mills theory}, Comm. Math. Phys. Volume 61, Number 2 (1978), 97-118 (\href{https://projecteuclid.org/euclid.cmp/1103904210}{arXiv:1103904210}) \end{itemize} In speculation regarding [[Galois theory]] over the [[sphere spectrum]]: \begin{itemize}% \item [[Jack Morava]], [[Jonathan Beardsley]], \emph{Toward a Galois theory of the integers over the sphere spectrum}, Journal of Geometry and Physics Volume 131, September 2018, Pages 41-51 (\href{https://arxiv.org/abs/1710.05992}{arXiv:1710.05992}) \end{itemize} \hypertarget{stable_splitting_of_mapping_spaces_2}{}\subsubsection*{{Stable splitting of mapping spaces}}\label{stable_splitting_of_mapping_spaces_2} The appearance of configuration spaces as summands in [[stable splittings of mapping spaces]] is originally due to \begin{itemize}% \item [[Victor Snaith]], \emph{A stable decomposition of $\Omega^n S^n X$}, Journal of the London Mathematical Society 7 (1974), 577 - 583 (\href{https://www.maths.ed.ac.uk/~v1ranick/papers/snaiths.pdf}{pdf}) \end{itemize} An alternative proof is due to \begin{itemize}% \item [[Ralph Cohen]], \emph{Stable proof of stable splittings}, Math. Proc. Camb. Phil. Soc., 1980, 88, 149 (\href{https://doi.org/10.1017/S030500410005742X}{doi:10.1017/S030500410005742X}, \href{https://www.cambridge.org/core/services/aop-cambridge-core/content/view/247D9F951F8AB99000E4FF6CB2DB9EA2/S030500410005742Xa.pdf/div-class-title-stable-proofs-of-stable-splittings-div.pdf}{pdf}) \end{itemize} Review and generalization is in \begin{itemize}% \item \hyperlink{Boedigheimer87}{Boedigheimer 87} \end{itemize} and the relation to the [[Goodwillie-Taylor tower]] of mapping spaces is pointed out in \begin{itemize}% \item \hyperlink{Arone99}{Arone 99} \end{itemize} \hypertarget{ReferencesInGoodwillieCalculus}{}\subsubsection*{{In Goodwillie-calculus}}\label{ReferencesInGoodwillieCalculus} The configuration spaces of a space $X$ appear as the [[Goodwillie derivatives]] of its [[mapping space]]/[[nonabelian cohomology]]-[[functor]] $Maps(X,-)$: \begin{itemize}% \item [[Greg Arone]], \emph{A generalization of Snaith-type filtration}, Transactions of the American Mathematical Society 351.3 (1999): 1123-1150. (\href{https://www.ams.org/journals/tran/1999-351-03/S0002-9947-99-02405-8/S0002-9947-99-02405-8.pdf}{pdf}) \item [[Michael Ching]], \emph{Calculus of Functors and Configuration Spaces}, Conference on Pure and Applied Topology Isle of Skye, Scotland, 21-25 June, 2005 (\href{https://www3.amherst.edu/~mching/Work/skye.pdf}{pdf}) \end{itemize} \hypertarget{ReferencesCompactification}{}\subsubsection*{{Compactification}}\label{ReferencesCompactification} A [[compactification]] of configuration spaces of points was introduced in \begin{itemize}% \item [[William Fulton]], [[Robert MacPherson]], \emph{A compactification of configuration spaces}, Ann. of Math. (2), 139(1):183–225, 1994. \end{itemize} and an [[operad]]-[[structure]] defined on it ([[Fulton-MacPherson operad]]) in \begin{itemize}% \item [[Ezra Getzler]], [[John Jones]], \emph{Operads, homotopy algebra and iterated integrals for double loop spaces} (\href{https://arxiv.org/abs/hep-th/9403055}{arXiv:hep-th/9403055}) \end{itemize} Review includes \begin{itemize}% \item [[Pascal Lambrechts]], [[Ismar Volić]], section 5 of \emph{Formality of the little N-disks operad}, Memoirs of the American Mathematical Society ; no. 1079, 2014 (\href{https://arxiv.org/abs/0808.0457}{arXiv``0808.0457}, \href{http://dx.doi.org/10.1090/memo/1079}{doi:10.1090/memo/1079}) \end{itemize} This underlies the models of configuration spaces by [[graph complexes]], see there for more. \hypertarget{ReferencesCohomology}{}\subsubsection*{{Homology and cohomology}}\label{ReferencesCohomology} General discussion of [[ordinary homology]]/[[ordinary cohomology]] of configuration spaces of points: \begin{itemize}% \item [[Vladimir Arnold]], \emph{The cohomology ring of the colored braid group}, Mat. Zametki, 1969, Volume 5, Issue 2, Pages 227–231 (\href{http://mi.mathnet.ru/eng/mz6827}{mathnet:mz6827}) \item [[Fred Cohen]], \emph{Cohomology of braid spaces}, Bull. Amer. Math. Soc. Volume 79, Number 4 (1973), 763-766 (\href{https://projecteuclid.org/euclid.bams/1183534761}{euclid:1183534761}) \item [[Fred Cohen]], \emph{The homology of $C_{n+1}$-Spaces, $n \geq 0$}, In: \emph{The Homology of Iterated Loop Spaces}, Lecture Notes in Mathematics, vol 533. Springer 1976(\href{https://doi.org/10.1007/BFb0080467}{doi:10.1007/BFb0080467}) \item [[Carl-Friedrich Bödigheimer]], [[Fred Cohen]], L. Taylor, \emph{On the homology of configuration spaces}, Topology Vol. 28 No. 1, p. 111-123 1989 (\href{https://core.ac.uk/download/pdf/82124359.pdf}{pdf}) \item E. Ossa, \emph{On the cohomology of configuration spaces}, In: Broto C., [[Carles Casacuberta]], Mislin G. (eds.), \emph{Algebraic Topology: New Trends in Localization and Periodicity}, Progress in Mathematics, vol 136. Birkhäuser Basel (1996) (\href{https://doi.org/10.1007/978-3-0348-9018-2_26}{doi:10.1007/978-3-0348-9018-2\_26}) \item [[Yves Félix]], [[Jean-Claude Thomas]], \emph{Rational Betti numbers of configuration spaces}, Topology and its Applications, Volume 102, Issue 2, 8 April 2000, Pages 139-149 () \item [[Oscar Randal-Williams]], \emph{Homological stability for unordered configuration spaces}, The Quarterly Journal of Mathematics, Volume 64, Issue 1, March 2013, Pages 303–326 (\href{https://arxiv.org/abs/1105.5257}{arXiv:1105.5257}) \item [[Yves Félix]], [[Daniel Tanré]], \emph{The cohomology algebra of unordered configuration spaces}, Journal of the LMS, Vol 72, Issue 2 (\href{https://arxiv.org/abs/math/0311323}{arxiv:math/0311323}, \href{https://doi.org/10.1112/S0024610705006794}{doi:10.1112/S0024610705006794}) \item Thomas Church, \emph{Homological stability for configuration spaces of manifolds} (\href{https://arxiv.org/abs/1602.04748}{arxiv:1602.04748}) \item [[Ben Knudsen]], \emph{Betti numbers and stability for configuration spaces via factorization homology}, Algebr. Geom. Topol. 17 (2017) 3137-3187 (\href{https://arxiv.org/abs/1405.6696}{arXiv:1405.6696}) \item Christoph Schiessl, \emph{Betti numbers of unordered configuration spaces of the torus} (\href{https://arxiv.org/abs/1602.04748}{arxiv:1602.04748}) \item Christoph Schiessl, \emph{Integral cohomology of configuration spaces of the sphere} (\href{https://arxiv.org/abs/1801.04273}{arxiv:1801.04273}) \item Dan Petersen, \emph{Cohomology of generalized configuration spaces} (\href{https://arxiv.org/abs/1807.07293}{arXiv:1807.07293}) \item Roberto Pagaria, \emph{The cohomology rings of the unordered configuration spaces of the torus} (\href{https://arxiv.org/abs/1901.01171}{arxiv:1901.01171}) \end{itemize} \hypertarget{homotopy}{}\subsubsection*{{Homotopy}}\label{homotopy} Discussion of [[homotopy groups]] of configuration spaces: \begin{itemize}% \item \hyperlink{Kohno02}{Kohno 02} \item [[Pascal Lambrechts]], [[Victor Tourtchine]], \emph{Homotopy graph-complex for configuration and knot spaces}, Transactions of the AMS, Volume 361, Number 1, January 2009, Pages 207–222 (\href{https://arxiv.org/abs/math/0611766}{arxiv:math/0611766}) \item [[Sadok Kallel]], Ines Saihi, \emph{Homotopy Groups of Diagonal Complements}, Algebr. Geom. Topol. 16 (2016) 2949-2980 (\href{https://arxiv.org/abs/1306.6272}{arXiv:1306.6272}) \end{itemize} \hypertarget{rational_homotopy_type_2}{}\subsubsection*{{Rational homotopy type}}\label{rational_homotopy_type_2} Discussion of the [[rational homotopy type]]: \begin{itemize}% \item [[Igor Kriz]], \emph{On the Rational Homotopy Type of Configuration Spaces}, Annals of Mathematics Second Series, Vol. 139, No. 2 (Mar., 1994), pp. 227-237 (\href{https://www.jstor.org/stable/2946581}{jstor:2946581}) \end{itemize} \hypertarget{cohomology_modeled_by_graph_complexes}{}\subsubsection*{{Cohomology modeled by graph complexes}}\label{cohomology_modeled_by_graph_complexes} That the [[de Rham cohomology]] of (the [[Fulton-MacPherson compactification]] of) configuration spaces of points may be modeled by [[graph complexes]] (exhibiting [[formality of the little n-disk operad]]) is due to \begin{itemize}% \item [[Maxim Kontsevich]], around Def. 15 and Lemma 3 in \emph{Operads and Motives in Deformation Quantization}, Lett.Math.Phys.48:35-72,1999 (\href{https://arxiv.org/abs/math/9904055}{arXiv:math/9904055}) \end{itemize} nicely reviewed in \hyperlink{LambrechtsVolic14}{Lambrechts-Volic 14} Further discussion of the graph complex as a model for the [[de Rham cohomology]] of [[configuration spaces of points]] is in \begin{itemize}% \item Najib Idrissi, \emph{The Lambrechts-Stanley Model of Configuration Spaces}, Invent. Math, 2018 (\href{https://arxiv.org/abs/1608.08054}{arXiv:1608.08054}, \href{https://dx.doi.org/10.1007/s00222-018-0842-9}{doi:10.1007/s00222-018-0842-9}) \item [[Ricardo Campos]], [[Thomas Willwacher]], \emph{A model for configuration spaces of points} (\href{https://arxiv.org/abs/1604.02043}{arXiv:1604.02043}) \item [[Ricardo Campos]], Najib Idrissi, [[Pascal Lambrechts]], [[Thomas Willwacher]], \emph{Configuration Spaces of Manifolds with Boundary} (\href{https://arxiv.org/abs/1802.00716}{arXiv:1802.00716}) \item [[Ricardo Campos]], Julien Ducoulombier, Najib Idrissi, [[Thomas Willwacher]], \emph{A model for framed configuration spaces of points} (\href{https://arxiv.org/abs/1807.08319}{arXiv:1807.08319}) \end{itemize} \hypertarget{ReferencesLoopSpacesOfConfigurationSpaces}{}\subsubsection*{{Loop spaces of configuration spaces of points}}\label{ReferencesLoopSpacesOfConfigurationSpaces} On [[loop spaces]] of [[configuration spaces of points]]: \begin{itemize}% \item [[Edward Fadell]], [[Sufian Husseini]], \emph{The space of loops on configuration spaces and the Majer-Terracini index}, Topol. Methods Nonlinear Anal. Volume 11, Number 2 (1998), 249-271 (\href{https://projecteuclid.org/euclid.tmna/1476842829}{euclid:tmna/1476842829}) \item [[Fred Cohen]], [[Samuel Gitler]], \emph{Loop spaces of configuration spaces, braid-like groups, and knots}, In: Aguadé J., Broto C., [[Carles Casacuberta]] (eds.) \emph{Cohomological Methods in Homotopy Theory}. Progress in Mathematics, vol 196. Birkhäuser, Basel (\href{https://doi.org/10.1007/978-3-0348-8312-2_7}{doi:10.1007/978-3-0348-8312-2\_7}) \item [[Toshitake Kohno]], \emph{Loop spaces of configuration spaces and finite type invariants}, Geom. Topol. Monogr. 4 (2002) 143-160 (\href{https://arxiv.org/abs/math/0211056}{arXiv:math/0211056}) \item [[Fred Cohen]], [[Samuel Gitler]], \emph{On loop spaces of configuration spaces}, Trans. Amer. Math. Soc. \textbf{354} (2002), no. 5, 1705--1748, (\href{https://www.jstor.org/stable/2693715}{jstor:2693715}, \href{http://www.ams.org/mathscinet-getitem?mr=1881013}{MR2002m:55020}) (on [[ordinary homology]] of [[loop spaces]] of configuration spaces) \end{itemize} \hypertarget{AsModuliOfD0D4BraneBoundStates}{}\subsubsection*{{As moduli of Dp-D(p+4)-brane bound states:}}\label{AsModuliOfD0D4BraneBoundStates} Discussion of [[configuration spaces of points]] as [[moduli spaces]] of [[D0-D4-brane bound states]] \begin{itemize}% \item [[Cumrun Vafa]], \emph{Instantons on D-branes}, Nucl. Phys. B463 (1996) 435-442 (\href{https://arxiv.org/abs/hep-th/9512078}{arXiv:hep-th/9512078}) \end{itemize} with emphasis to the resulting [[configuration spaces of points]], as in \begin{itemize}% \item [[Cumrun Vafa]], [[Edward Witten]], Section 4.1 of: \emph{A Strong Coupling Test of S-Duality}, Nucl. Phys. B431:3-77, 1994 (\href{https://arxiv.org/abs/hep-th/9408074}{arXiv:hep-th/9408074}) \end{itemize} [[!redirects configuration spaces of points]] [[!redirects configuration space of n points]] [[!redirects configuration spaces of n points]] [[!redirects ordered configuration space of points]] [[!redirects ordered configuration spaces of points]] [[!redirects ordered configuration space of n points]] [[!redirects ordered configuration spaces of n points]] [[!redirects unordered configuration space of points]] [[!redirects unordered configuration spaces of points]] [[!redirects unordered configuration space of n points]] [[!redirects unordered configuration spaces of n points]] [[!redirects configuration space (mathematics)]] [[!redirects configuration spaces (mathematics)]] \end{document}