8.3.3. Diagonal bimodule
Recall that we have a -bimodule
. Its restriction to a -bimodule is the
cone of .
The -bimodule is the
cone of the map defined as follows.
Given with and given , we have
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We construct now an isomorphism between and the restriction of
to a -bimodule.
We define two morphisms of pointed sets
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and
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Note that we have an isomorphism of pointed sets
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0PDY
Lemma 8.3.4. We have and
.
There is an isomorphism of differential modules
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functorial in and .
0PDZ
Proof. It is immediate that . For the second equality,
consider and .
Since
, we can assume that . We have
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We have
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hence
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The lemma follows.
∎