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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*{iterated loop space} \hypertarget{context}{}\subsubsection*{{Context}}\label{context} \hypertarget{homotopy_theory}{}\paragraph*{{Homotopy theory}}\label{homotopy_theory} [[!include homotopy - contents]] \hypertarget{contents}{}\section*{{Contents}}\label{contents} \noindent\hyperlink{idea}{Idea}\dotfill \pageref*{idea} \linebreak \noindent\hyperlink{properties}{Properties}\dotfill \pageref*{properties} \linebreak \noindent\hyperlink{cohomology}{Cohomology}\dotfill \pageref*{cohomology} \linebreak \noindent\hyperlink{relation_to_configuration_spaces_of_points}{Relation to configuration spaces of points}\dotfill \pageref*{relation_to_configuration_spaces_of_points} \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{relation_to_configuration_spaces_of_points_2}{Relation to configuration spaces of points}\dotfill \pageref*{relation_to_configuration_spaces_of_points_2} \linebreak \noindent\hyperlink{rational_cohomology}{Rational cohomology}\dotfill \pageref*{rational_cohomology} \linebreak \hypertarget{idea}{}\subsection*{{Idea}}\label{idea} A multiple [[loop space]]. A grouplike [[E-k algebra]] in [[Top]]. An [[iterated loop space object]] in [[Top]]. \hypertarget{properties}{}\subsection*{{Properties}}\label{properties} \hypertarget{cohomology}{}\subsubsection*{{Cohomology}}\label{cohomology} \begin{prop} \label{RationalCohomologyOfIteratedLoopSpaceOf2kSphere}\hypertarget{RationalCohomologyOfIteratedLoopSpaceOf2kSphere}{} \textbf{([[rational cohomology]] of [[iterated loop space]] of the [[n-sphere|2k-sphere]])} Let \begin{displaymath} 1 \leq D \lt n = 2k \in \mathbb{N} \end{displaymath} (hence two [[positive number|positive]] [[natural numbers]], one of them required to be [[even number|even]] and the other required to be smaller than the first) and consider the [[iterated loop space|D-fold loop space]] $\Omega^D S^n$ of the [[n-sphere]]. Its [[rational cohomology|rational]] [[cohomology ring]] is the [[free construction|free]] [[graded-commutative algebra]] over $\mathbb{Q}$ on one [[generators and relations|generator]] $e_{n-D}$ of degree $n - D$ and one generator $a_{2n - D - 1}$ of degree $2n - D - 1$: \begin{displaymath} H^\bullet \big( \Omega^D S^n , \mathbb{Q} \big) \;\simeq\; \mathbb{Q}\big[ e_{n - D}, a_{2n - D - 1} \big] \,. \end{displaymath} \end{prop} (\hyperlink{KallelSjerve99}{Kallel-Sjerve 99, Prop. 4.10}) $\backslash$linebreak \hypertarget{relation_to_configuration_spaces_of_points}{}\subsubsection*{{Relation to configuration spaces of points}}\label{relation_to_configuration_spaces_of_points} \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 electric field map/[[scanning map]] constitutes a [[homotopy equivalence]] \begin{displaymath} Conf\left( \mathbb{R}^d, Y \right) \overset{scan}{\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{scan}{\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 electric field map/[[scanning 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 scan}{\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{related_concepts}{}\subsection*{{Related concepts}}\label{related_concepts} [[!include k-monoidal table]] \hypertarget{references}{}\subsection*{{References}}\label{references} \hypertarget{general}{}\subsubsection*{{General}}\label{general} \begin{itemize}% \item [[Peter May]], \emph{Infinite loop space theory}, Bull. Amer. Math. Soc. Volume 83, Number 4 (1977), 456-494. (\href{http://projecteuclid.org/DPubS?service=UI&version=1.0&verb=Display&handle=euclid.bams/1183538891}{Euclid}) \emph{Infinite loop space theory revisited} (\href{http://www.math.uchicago.edu/~may/PAPERS/28.pdf}{pdf}) \item [[John Adams]], \emph{Infinite loop spaces}, Herrmann Weyl lectures at IAS, Princeton University Press (1978) \item [[Peter May]], \emph{The uniqueness of infinite loop space machines}, Topology, vol 17, pp. 205-224 (1978) (\href{http://www.math.uchicago.edu/~may/PAPERS/22.pdf}{pdf}) \item [[Jacob Lurie]], Section 5.1.3 of \emph{[[Higher Algebra]]} \end{itemize} \hypertarget{relation_to_configuration_spaces_of_points_2}{}\subsubsection*{{Relation to configuration spaces of points}}\label{relation_to_configuration_spaces_of_points_2} In relation to [[configuration spaces of points]]: \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}) \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}) \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]]) \end{itemize} \hypertarget{rational_cohomology}{}\subsubsection*{{Rational cohomology}}\label{rational_cohomology} On [[ordinary cohomology]] of iterated loop spaces in relation to [[configuration spaces of points]] (see also at \emph{[[graph complex]]}): \begin{itemize}% \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}) \end{itemize} On the [[rational cohomology]]: \begin{itemize}% \item [[Sadok Kallel]], [[Denis Sjerve]], \emph{On Brace Products and the Structur eof Fibrations with Section}, 1999 (\href{https://www.math.ubc.ca/~sjer/brace.pdf}{pdf}, [[KallelSjerv99.pdf:file]]) \end{itemize} [[!redirects iterated loop spaces]] [[!redirects iterated based loop space]] [[!redirects iterated based loop spaces]] [[!redirects n-fold loop space]] [[!redirects n-fold loop spaces]] \end{document}