Fuzzy time series and its models

Based upon the works by Zadeh, in this paper, a special dynamic process with linguistic values as its observations is defined and studied. This dynamic process is called fuzzy time series. To describe fuzzy time series, fuzzy relational equations are employed as the models. There are two classes of fuzzy time series: time-variant and time-invariant. The definition of fuzzy time series is given, some properties of fuzzy time series are explored, and procedures to develop fuzzy time series models are discussed. Finally, a procedure for using fuzzy time series for forecasting is suggested.