Table 4 Symbol description

\(\theta (i)\)

The weight of the data in bar \(i\) in the window

\(C{P_S}\)

Concept drift checkpoint within a short window

\(ms\)

Minimum support threshold

\(MTh\)

Frequent pattern change rate \(FChange\) test minimum threshold

\(Rt\)

Minimum threshold for the conceptual drift test index \(R\)

\(LW\)

Long window

\(SW\)

Short window

\(\lambda\)

Log-type membership function parameter value

\(SF_{t_i}\)

Frequent set of items within a short window at the time \({t_i}\)

\(SF_{t_i}^+ ({t_j})\)

The set of new frequent term sets at \({t_j}\) within a short window relative to \({t_i}\)

\(SF_{t_i}^- ({t_j})\)

Within a short window, the set of items infrequent at \({t_j}\), but the set of items frequent at \({t_i}\)

\(SFChang{e_{t_i}}({t_j})\)

The change rate of the frequent term set at the \({t_j}\) within the short window relative to the \({t_i}\)

\(LFChang{e_{t_i}}({t_j})\)

The change rate of the frequent term set at the \({t_j}\) within the long window relative to the \({t_i}\)