Fuzzy transform; F-transform; evaluative linguistic expressions; fuzzy natural logic; time series

In this paper we suggest to use special fuzzy modeling techniques for detection of structural breaks and perceptionally important points in time series, namely the fuzzy (F-)transform and one method of Fuzzy Natural Logic (FNL). The idea is based on application of the F^1-transform which makes it possible to estimate effectively slope of time series over an imprecisely specified area (ignoring its possible volatility) and its evaluation by a suitable evaluative linguistic expression. The method is computationally very effective.