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Results tagged with crossed-modules
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user 3473
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Accepted
Long exact sequence of cohomology from 2-groups
$c$ is your crossed module, or 2-group, in a sense. Anything more concrete will depend on a choice of a cocycle description of the pointed set $[BH,B^3A]$.
For example, $[BH,B^3A]$ classifies central …
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