3 papers
math.DG2025
Quaternion-Kähler manifolds with non-negative quaternionic sectional curvature
Andrei Moroianu, Uwe Semmelmann, Gregor Weingart
Compact Hermitian symmetric spaces are Kähler manifolds with constant scalar curvature and non-negative sectional curvature. A famous result by A. Gray states that, conversely, a…
math.DG2024
On quaternionic bisectional curvature
Oscar Macia, Uwe Semmelmann, Gregor Weingart
In this article we study the concept of quaternionic bisectional curvature introduced by B. Chow and D. Yang for quaternion-Kähler manifolds. We show that non-negative quaternioni…
math.DG2024
A Graphical Calculus for Stable Curvature Invariants
Gregor Weingart
In this article we develop a graphical calculus for stable invariants of Riemannian manifolds akin to the graphical calculus for Rozansky-Witten invariants for hyperkähler manifol…