2 papers
math.AP2025
Elliptic systems generating a positive semigroup are decoupled
Wolfgang Arendt, A. F. M. ter Elst, Manfred Sauter
We show that the semigroup associated to a second-order elliptic system is positive if and only if the differential equations are essentially decoupled and the coefficients are rea…
math.AP2025
Commutator estimates and Poisson bounds for Dirichlet-to-Neumann operators
A. F. M. ter Elst, E. M. Ouhabaz
We consider the Dirichlet-to-Neumann operator associated with a general elliptic operator \[ {\cal A} u = - \sum_{k,l=1}^d \partial_k (c_{kl}\, \partial_l u) + \sum_{k=1…