On homology spheres of the trivial local equivalence class

Abstract: In the homology cobordism group $\Theta_{\mathbb{Z}}^3$, it is not known if there is a non-trivial linear dependence between Seifert fibered spheres. Based on involutive Heegaard Floer theory, Hendricks, Manolescu, and Zemke introduced the local equivalence group $\mathfrak{I}$ with the homomorphism $h:\Theta_{\mathbb{Z}}^3 \rightarrow \mathfrak{I}$. And it is possible to find a non-trivial linear dependence between the image of Seifert fibered spheres in $\mathfrak{I}$ using the work of Dai and Stoffregen. Therefore, it is interesting to ask if such a linear dependence in $\mathfrak{I}$ originates from $\Theta_{\mathbb{Z}}^3$. In this paper, we prove that this is not the case in general. We show that infinitely many homology spheres linearly dependent in $\mathfrak{I}$ are linearly independent even in the rational homology cobordism group $\Theta_{\mathbb{Q}}^3$, by employing the $r_s$-invariants from the filtered instanton Floer homology developed by Nozaki, Sato, and Taniguchi. Moreover, these homology spheres include homology spheres of the trivial local equivalence class of $\operatorname{Pin(2)}$-equivariant Seiberg--Witten Floer stable homotopy type.