Comparison principle for Walsh's spider HJB equations with non linear local time Kirchhoff's boundary transmission
Isaac Ohavi
TL;DR
This work addresses a Walsh spider HJB system posed on a star-shaped network with a non-linear local-time Kirchhoff boundary at the vertex, establishing a comparison principle for viscosity solutions and hence uniqueness. The authors introduce a novel vertex testing mechanism built from parametric ODEs that captures the envelope of the Kirchhoff-speed and employs a local-time derivative with respect to $l$ to absorb transmission errors. Notably, the result does not rely on vanishing viscosity at the vertex and extends to unbounded local time, as well as to strong Neumann-type boundary formulations. The methodological advance enhances the theory of HJB systems on networks with discontinuous coefficients and local-time dynamics, with potential implications for diffusion control, scattering, and quantum trajectory models.
Abstract
The main purpose of this work is to obtain a comparison principle for viscosity solutions of a system of elliptic Walsh's spider Hamilton-Jacobi-Bellman equations, possessing a new boundary condition called non linear local-time Kirchhoff's transmission. The main idea is to build test functions at the neighborhood of the vertex solutions of ODE, with well-designed coefficients. The key point is to impose a 'local-time' derivative at the vertex absorbing the error term induced by - what we decide to call here - the Kirchhoff's speed of the Hamiltonians.
