An excercise question for time series analysis asks:
Consider the process $$ y_t = 0.8y_{t-1} 0.1y_{t-2} + u_t $$$$ y_t = 0.8y_{t-1} + 0.1y_{t-2} + u_t $$
Is this process weakly stationary (I would answer this with the stability triangle)
Under which assumptions does this property imply strong stationarity
I thought that strong stationarity always implies weak stationarity, but not that it can be the other way around.