The inverse-limit comparison conjecture for Hopf-cyclic cohomology of coalgebras

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Let CC be a coalgebra, M{\mathcal M} a coefficient module, and H{\mathcal H} a Hopf algebra. Let W(C)W(C) and I(C)I(C) be the constructions appearing in the associated supercomplex XH(W(C),I(C);M){\mathcal X}_{\mathcal H}(W(C),I(C);{\mathcal M}). The map

HCH∗(C,M)→H∗(XH(W(C),I(C);M))HC^*_{\mathcal H}(C,{\mathcal M})\to H^*({\mathcal X}_{\mathcal H}(W(C),I(C);{\mathcal M}))

is defined by the inverse-limit construction described before the conjecture.

Inverse-limit comparison conjecture. The map above is an isomorphism of the cohomology groups.

This conjecture proposes that Hopf-cyclic cohomology of the coalgebra with coefficients is recovered by the cohomology of the associated supercomplex. The supplied text gives no resolution or status evidence, so it remains open.

References

Primary source

I. Nikonov and G. Sharygin, “Pairings in Hopf-cyclic cohomology of algebras and coalgebras with coefficients”, arXiv:math/0610615 (2006).

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