Thanks for your explanation. At the last step, is the support of {abfe} = 2? It seems that support of {abfe} = 1. Would you mind to answer this please?
{(ab)} is frequent and {b,f} is frequent and the have common item b. So we can join those two sequences to form 3-length sequence. While forming 3-length sequence in first sequence a,b are in same transaction and in second sequence b,f are in different transactions. Therefore we form 3-length sequence {(a,b),f}.
minsupport=3/4 means subsequence need to be present in at least 3 sequences where 4 is the total number of sequences. In this video, Example has a total of 4 sequences and considered minsup=2 which means subsequence must be present in at least 2 sequences out of 4. therefore minsup that we considered is actually 2/4
