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sequences that the pattern matches and potentially increasing precision, but
possibly at the expense of a decrease in recall (specication eect).
3. e count of patterns (frequent sequences) may change as occurrences that
are not frequent per se may become frequent via taxonomic generalization.
Recall may yield more patterns at the cost of a possible decrease in precision.
(We show an example of this eect in Section 8.6.4.)
Figure8.3 illustrates case 1 with dashed arrows, case 2 with solid arrows, and
case 3 with dotted arrows. ese cases constitute classical precision–recall trade-
os, but the crucial ques