homology ring of loop space is group ring with loop space of universal cover
Proposition
Let be an anima and
be a fiber sequence for the universal cover.
Then the homology ring of is given by the group ring
Proof
using loop space is a coproduct of the loop space of the universal cover we get
This shows the additive isomorphism
Now we want to identify the multiplication:
Here under the above equivalence the connected corresponding to
acts (under the identification of
used by connected components of an anima valued group equivalent) by mapping the
-th component to the
resp.
-th component - depending whether we multiply from the left or the right.
Thus
Therefore we get the multiplication
and analogously
Furthermore the inclusion
is a map of loop spaces, hence is a map of groups.
Thus the multiplication of since
is map of graded rings (and inclusion of connected components).
Therefore we get in general
which is precisely the presentation of a group ring :)