more on commutator subgroups #3372

Job	Run time
quick-build (supported, ubuntu-latest)	2m 16s
build (supported)	2m 17s
nix	2m 19s
quick-build (latest, ubuntu-latest)	2m 16s
opam-build (supported, ubuntu-latest)	2m 16s
build (latest)	2m 16s
opam-build (latest, ubuntu-latest)	2m 16s
build (dev, --warnings)	2m 13s
quick-build (dev, ubuntu-latest)	2m 17s
opam-build (dev, ubuntu-latest)	2m 16s
doc-dep-graphs	1s
doc-timing	1s
doc-alectryon	1s
coqchk	1s
doc-coqdoc	1s
install	1s
deploy-doc	1s
delete-artifacts	5s
	22m 54s

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