Spectral generalized Tur\'{a}n problems

Combining two well-studied variants of the classical Tur\'{a}n problem, the generalized Tur\'{a}n problem and the spectral Tur\'{a}n problem, we introduce the spectral generalized Tur\'{a}n problem and establish a general theorem that extends the result of Keevash--Lenz--Mubayi~\cite{KLM14} on the spectral Tur\'{a}n problem in this broader setting. As a quick application, we obtain the spectral Erd\H{o}s Pentagon Theorem. We also introduce the notion of entropic density for generalized Tur\'{a}n problems, and show that it coincides with the generalized spectral radius, extending a recent result of Chao--Hans on entropic Tur\'{a}n density.