“…A locally stationary process, as introduced by Dahlhaus (1996,1997), is an extension of the linear stationary process and can be represented in terms of the spectral density as follows where is a stochastic process with a mean value equal to 0 and orthogonal increment, . Based on this framework, a large number of topics related to locally stationary processes have been studied, including bootstrap methods for the local periodogram (Sergides and Paparoditis 2008), hypothesis testing (Sakiyama and Taniguchi 2003), the locally stationary factor model (Eichler et al 2011) and estimation methods (Chan and Palma 2020), among many others.…”