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A principle bundle over a topological space can be given by transitions functions. On the other hand, in the simplicial world principle bundles can be given by twisting functions. Is there an explicit description of this relationship written up somewhere? Or can anyone explain how it can be obtained?

Given a good topological space $B$ and a topological group $G$, a $G$-principle bundle over $B$ can be given by a collection of transition functions $t_{i,j} : U_i\cap U_j \rightarrow G$, where $\{U_i\}$ is an open cover of $B$ locally trivializing the bundle.

Analogously, for a simplicial set $B$ and a simplicial group $G$, a $G$-principle bundle over $B$ can be given by a twisting function $r$ which is a collection of maps $r_q : B_q \rightarrow G_{q-1}$.

The two concepts are analogous. The analogy makes me think of basic ideas of Čech methods. But, I could not find details about it written anywhere.

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    $\begingroup$ Have you looked in Chapter 4 of May's "Simplicial Objects in Algebraic Topology"? IIRC there's a mention there about how these things relate. $\endgroup$ Commented Apr 29, 2017 at 19:24
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    $\begingroup$ In both cases you can think of the collection of maps as representing a classifying morphism from B to the delooping of G in a relevant mapping space. Compare the topological case to the first property listed here. The first collection of maps is a map from the Čech groupoid of the cover to the delooping of G, which computes the right morphism when the cover locally trivializes the bundle. $\endgroup$ Commented Apr 29, 2017 at 19:33
  • $\begingroup$ One paper where (almost) this question is addressed directly is "Comparison of the geometric bar and W-constructions" by Berger and Hübschmann (JPAA 1998). They construct a natural homeomorphism from the geometric realization of the $W$-construction of a simplicial group $G$ to the universal principal $|G|$-bundle (the latter is the geometric realization of $G$). $\endgroup$ Commented Apr 29, 2017 at 19:37

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