Reducibility of linear representations, free ideals, and Kippenhahn's conjecture

This paper presents a comprehensive study of the characteristic polynomial of matrix tuples and finite dimensional group representations. Among other things, several key concepts are introduced, including the minimal polynomial, spectral index, spectral stability, and characteristic graph. Notably, this framework provides a complete resolution to Kippenhahn’s conjecture, settling a long-standing and influential problem in the theory of matrix tuples.