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I'm learning about loop spaces and the work of Stasheff on $A_{\infty}$-spaces. The broad idea that I'm getting is the following. Given a space $Y$, we want to know under which conditions there exists some space $X$ such that $Y$ is the space of loops of $X$, $Y = \Omega X$ (without previously assuming the existence of such $X$). And such space $X$ exists if and only if $Y$ is an $A_{\infty}$-space (plus some obvious requirements on the homotopy groups of $Y$).

The question that naturally comes to my mind is the following: is there any similar detection tool for reduced suspensions? That is, given a space $X$, is there any general criterion to known whether or not there exists a space $Y$ such that $X$ is the reduced suspension of $Y$, $X = \Sigma Y$? I am assuming all spaces to be pointed.

Many thanks in advance!

AGdM
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  • As far as I know, the answer to your question is no. – Ryan Budney Jan 22 '16 at 04:41
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    Klein's answer in http://mathoverflow.net/questions/4117/when-can-you-desuspend-a-homotopy-cogroup answers your question positively for 2-connected spaces and states it as open otherwise. – Fernando Muro Jan 22 '16 at 06:01
  • One may formally try to say that something like suitable co-algebras over co-operads will do the job; in the line of above comments. But, I think in terms of geometry this could be more difficult than the `adjoint' problem on loop spaces. If you think about finite dimensional CW-complexes then the question is equivalent to ``if the attaching maps desuspend'' which is a question about the Hopf invariant of the attaching maps. Sometimes, facts like Freudenthal's theorem imply that if the difference between top and bottom cell are in the stable range then the complex desuspends. – user51223 Jan 23 '16 at 10:14

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