On the ER(2) cohomology of some odd dimensional projective spaces

TL;DR

This paper extends the computation of ER(2) cohomology to certain odd-dimensional real projective spaces, providing new obstructions to their non-immersion properties.

Contribution

It computes ER(2) cohomology for specific odd-dimensional projective spaces, advancing the understanding of non-immersion phenomena via ER(2)-cohomology.

Findings

Computed ER(2) cohomology of RP^{16K+9}

Provided new non-immersion obstructions for these spaces

Extended previous results by Kitchloo and Wilson

Abstract

Kitchloo and Wilson have used the homotopy fixed points spectrum ER(2) of the classical complex-oriented Johnson-Wilson spectrum E(2) to deduce certain non-immmersion results for real projective spaces. ER(n) is a $2^{n+2}(2^n-1)$-periodic spectrum. The key result to use is the existence of a stable cofibration $\Sigma^{\lambda(n)}ER(n) \rightarrow ER(n) \rightarrow E(n)$ connecting the real Johnson-Wilson spectrum with the classical one. The value of $\lambda(n)$ is $2^{2n+1}-2^{n+2}+1$. We extend Kitchloo-Wilson's results on non-immersions of real projective spaces by computing the second real Johnson-Wilson cohomology ER(2) of the odd-dimensional real projective spaces $RP^{16K+9}$. This enables us to solve certain non-immersion problems of projective spaces using obstructions in ER(2)-cohomology.