Irregular subsets of the Grassmannian manifolds

An $E_\infty$ structure on the matroid grassmannian

In analogy with the origin of the additive structure of $K$-theory, we construct an $E_\infty$ structure on the matroid Grassmannian (the space of oriented matroids) for which the underlying binary operation is the direct sum of matroids. The proof involves lifting the polyhedral fan structure of the Dressian to a polyhedral model for the matroid Grassmannian, and introducing a novel $E_\infty$ operad made from the space of infinite subsets of $\mathbb{N}$.

Topology and geometry of the canonical action of $T^4$ on the complex Grassmannian $G_{4,2}$ and the complex projective space $CP^{5}$

We consider the canonical action of the compact torus $T^4$ on the Grassmann manifold $G_{4,2}$ and prove that the orbit space $G_{4,2}/T^4$ is homeomorphic to the sphere $S^5$. We prove that the induced differentiable structure on $S^5$ is not the smooth one and describe the smooth and the singular points. We also consider the action of $T^4$ on $CP^5$ induced by the composition of the second symmetric power $T^4\subset T^6$ and the standard action of $T^6$ on $CP^5$ and prove that the orbit space $CP^5/T^4$ is homeomorphic to the join $CP^2\ast S^2$. The Plücker embedding $G_{4,2}\subset CP^…

定向格拉斯曼包、法向曲率降维与持久同调

Oriented Grassmannian Bundle, Normal Curvature Reduction, and Persistent Homology

本文提出通过定向格拉斯曼包嵌入光滑闭合子流形，以降低法向曲率并增强持久同调的稳定性，从而在特定尺度下恢复流形的同调结构。