The $mathbb Z$-homotopy fixed points of $C_{n}$ spectra with applications to norms of $MU_{mathbb R}$


الملخص بالإنكليزية

We introduce a computationally tractable way to describe the $mathbb Z$-homotopy fixed points of a $C_{n}$-spectrum $E$, producing a genuine $C_{n}$ spectrum $E^{hnmathbb Z}$ whose fixed and homotopy fixed points agree and are the $mathbb Z$-homotopy fixed points of $E$. These form a piece of a contravariant functor from the divisor poset of $n$ to genuine $C_{n}$-spectra, and when $E$ is an $N_{infty}$-ring spectrum, this functor lifts to a functor of $N_{infty}$-ring spectra. For spectra like the Real Johnson--Wilson theories or the norms of Real bordism, the slice spectral sequence provides a way to easily compute the $RO(G)$-graded homotopy groups of the spectrum $E^{hnmathbb Z}$, giving the homotopy groups of the $mathbb Z$-homotopy fixed points. For the more general spectra in the contravariant functor, the slice spectral sequences interpolate between the one for the norm of Real bordism and the especially simple $mathbb Z$-homotopy fixed point case, giving us a family of new tools to simplify slice computations.

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