Semibounded local hamiltonians for perturbations of the laplacian supported by curves with angle points in $\mathbb R^4$

Perturbations supported by curves with angle points are studied for the Laplacian in $\mathbb R^4$ within the framework of the extension theory. Classes of the self-adjoint extensions that are local, semibounded and generate a positivity preserving semigroup are distinguished. Their connection with the local Dirichlet forms is obtained.