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JOURNALS // Zapiski Nauchnykh Seminarov POMI // Archive

Zap. Nauchn. Sem. POMI, 2025 Volume 543, Pages 155–171 (Mi znsl7592)

$K(\mathbb{Z},2)$ out of circular permutations

N. E. Mnevab

a PDMI RAS
b Chebyshev Laboratory, SPbSU

Abstract: We discuss $SC_*$, a simplicial homotopy model of $K(\mathbb{Z},2)$ constructed from circular permutations. In any dimension, the number of simplices in the model is finite. The complex $SC_*$ naturally manifests as a simplicial set representing “minimally” triangulated circle bundles over simplicial bases. On the other hand, existence of the homotopy equivalence $|SC_*| \approx B(U(1)) \approx K(\mathbb{Z},2)$ appears to be a canonical fact from the foundations of the theory of crossed simplicial groups.

Key words and phrases: circle bundles, circular permutations, crossed simplicial groups.

UDC: 515.145.25, 515.145.82

Received: 18.09.2025

Language: English



© Steklov Math. Inst. of RAS, 2026