Self-Closeness Numbers of Rational Mapping Spaces

TL;DR

This paper determines the self-closeness numbers of rationalized mapping space components from rational Poincaré complexes to spheres, showing these invariants distinguish their rational homotopy types, thus extending previous results on manifolds.

Contribution

It provides a complete calculation of self-closeness numbers for components of mapping spaces from rational Poincaré complexes to spheres, revealing these numbers as distinguishing invariants.

Findings

Self-closeness numbers distinguish rational homotopy types of mapping space components.

Complete determination of self-closeness numbers for components from rational Poincaré complexes.

Extension of previous results from manifolds to rational Poincaré complexes.

Abstract

For a closed connected oriented manifold $M$ of dimension $2n$, it was proved by M\o ller and Raussen that the components of the mapping space from $M$ to $S^{2n}$ have exactly two different rational homotopy types. However, since this result was proved by the algebraic models for the components, it is unclear whether other homotopy invariants distinguish their rational homotopy types or not. The self-closeness number of a connected CW complex is the least integer $k$ such that any of its self-map inducing an isomorphism in $\pi_*$ for $*\le k$ is a homotopy equivalence, and there is no result on the components of mapping spaces so far. For a rational Poincar\'e complex $X$ of dimension $2n$ with finite $\pi_1$, we completely determine the self-closeness numbers of the rationalized components of the mapping space from $X$ to $S^{2n}$ by using their Brown-Szczarba models. As a corollary, we show that the self-closeness number does distinguish the rational homotopy types of the components. Since a closed connected oriented manifold is a rational Poincar\'e complex, our result partially generalizes that of M\o ller and Raussen.