Stack Exchange network consists of 183 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
@DmitriPavlov: Thank you so much, Dmitri. Do you think that the classification of the diagram of the form $A\langle n \rangle_\ast \stackrel{f}{\to} B\langle n \rangle_\ast \stackrel{g}{\to} C \langle n \rangle_\ast$ with $g\circ f \sim 0$, can be recovered form the $ho(Ch_\mathbb{Q})$ and the classification of the diagram of the type $E\langle n \rangle_\ast \to 0 \to \Sigma E\langle n \rangle_\ast$? Here $A\langle n \rangle_\ast$ is the chain complex concentrated in degree $n$ and $A\langle n \rangle_n=A.$
@NeilStrickland: I am reading your answer and I feel I have a question, which may not directly be related to the above. I just wondering what is $[H\underline{\mathbb{Z}/2}, \Sigma H\underline{\mathbb{Z}/2}]^{C_2}$?
@TomGoodwillie: Consider the localizations maps $X \to P^n X$, $Y \to P^n Y$ and $X \wedge Y \to P^n(X \wedge Y )$. Then can we have a map from $P^n(X) \wedge P^n(Y) \to P^n(X \wedge Y)?$ Here $P^n$ is the Postnikov section.