Past exam of the mathematics course of the University of Cambridge 2015 iii Paper 3 5 d Solution Created 2026-10-03 Updated 2026-10-06
An acyclic finite quiver has integer vertex weights such that for every arrow ; for example, let be the maximum length of a path ending at . For , act by . ThenEvery exponent is positive. The arrow matrices therefore extend polynomially to with all arrows zero, which is the origin of the quiver representation space. The values for lie in , soThis proves that acyclic quiver representations degenerate to zero, also when some vertex spaces are zero.