abstract: The geometric data of the positions of tiles in the level-one supertiles can be used to define a complex algebra, which we call the inflation displacement algebra (IDA). Its irreducibility has various consequences on the spectral structure of the dynamical system. We present a sufficient irreducibility criterion and then investigate the induced tensor product structure that is needed to infer properties of the correlation functions. In particular, we sketch an argument why a primitive inflation rule with an irreducible IDA cannot possess an absolutely continuous diffraction component.