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Let $\mathcal{J}$ be a small category and let $X : \mathcal{J} \to \mathbf{sSet}$ be a diagram. We define its homotopy colimit $\newcommand{\hocolim}{\mathop{\mathrm{ho}{\varinjlim}}}\hocolim X$ following Bousfield and Kan; more precisely, $\hocolim X = \operatorname{diag} T_{\bullet}$ where $T_{\bullet}$ is the bisimplicial set defined below: $$T_n = \coprod_{(j_0, \ldots, j_n)} \mathcal{J} (j_{n-1}, j_n) \times \cdots \times \mathcal{J} (j_0, j_1) \times X (j_0)$$

Question. I am led to believe that there are spectral sequences relating the (co)homology of the individual simplicial sets $X (j)$ and the (co)homology of $\hocolim X$. What is the precise statement, and where is it written in the literature?

For convenience, I quote Dugger:

Cohomology spectral sequence. Let $E$ be a spectrum. There is a spectral sequence with $$E_2^{p, q} = H^p (\mathcal{J}^\mathrm{op}, E^q (X))$$ and differentials $d : E_r^{p, q} \to E_r^{p + r, q - r + 1}$, converging to $E^{p - q} (\hocolim X)$.

Homology spectral sequence. Let $E$ be a spectrum. There is a spectral sequence with $$E^2_{p, q} = H_q (\mathcal{J}, E_p (X))$$ and differentials $d : E^r_{p, q} \to E^r_{p + r - 1, q - r}$, converging to $E_{p + q} (\hocolim X)$.

Specifically, I want to know whether the filtrations on $E^n (\hocolim X)$ and $E_n (\hocolim X)$ are exhaustive, canonically bounded, etc. (Actually, I'm not completely sure what Dugger means by $H_q (\mathcal{J}, -)$; I'm guessing he means the left derived functors of $\varinjlim$, by analogy with $H^q (\mathcal{J}^\mathrm{op}, -)$ being the right derived functors of $\varprojlim$.)

If it simplifies things, I'm only interested in the case where $E$ is an Eilenberg–MacLane spectrum.

Zhen Lin
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  • In the case of a cosimplicial diagram, there is the Lurie spectral sequence (you can find it in HA). This can be applied even when the diagram is not strict but commutes up to homotopy coherence. I am not sure this approach generalizes for arbitrary diagrams though... – Andrea Marino Apr 16 '23 at 20:54

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