Simpson filtrations and closure relations of Hodge moduli spaces

In this paper, we study closure relations of Simpson strata in Hodge moduli spaces over a smooth complex projective curve of genus $g\ge 2$ and prove in every rank that the Heinloth weight strictly increases whenever a specialization changes the fixed component. For stable full chains, we refine this numerical condition by comparing the degrees of the corresponding filtration steps and construct counterexamples to Simpson’s nestedness conjecture for the Dolbeault and de Rham moduli spaces in every rank $n\ge 4$. Using the maximum property of this weight, we also discuss Simpson filtrations from the viewpoint of $\mathrm{\Theta }$ stratifications.