This article features a case study of the following four relevant subjects: (i) the hypersurface potential on an m-homogeneous graph ; (ii) the hypersurface capacity on \(\Sigma \) ; (iii) the wave potential over a light cone \(\{y\in \mathbb R^n\hspace{0.55542pt}{:}\, |y|<t\}\) under the spherical symmetry with respect to the space variable; (iv) the existence and uniqueness of a weak solution to the model semilinear wave equation \(\Box \hspace{1.111pt}u=u|u|^{\kappa -1}\) in \(\mathbb R^3\hspace{0.55542pt}{\times }\hspace{1.111pt}(0,\infty )\) with rough-to-rougher Sobolev data.