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The following frequent 4-sequences were the only frequent 4-sequences generated by a candidate generation step:

<{1}{2}{3}{4}>
<{1}{2}{4}{5}>
<{1,2}{3,4}>
<{1,3}{4}{5}>
<{2}{3,4}{5}>
<{2}{3}{4}{5}>

Is it possible to merge <{1,2}{3,4;> and <{2}{3,4}{5}> and generate a 5-sequence? If yes, write down that sequence. If no, explain briefly.

1 Answer

4 votes

Final answer:

It is not possible to merge the sequences <{1,2}{3,4}> and <{2}{3,4}{5}> as there is no proper overlapping sequence. A valid merge requires a common 3-sequence at the end of the first sequence and the beginning of the second sequence, which does not exist in this case.

Step-by-step explanation:

The question asks if it is possible to merge two given frequent 4-sequences to generate a 5-sequence. The sequences in question are <{1,2}{3,4}> and <{2}{3,4}{5}>. To merge into a 5-sequence, there needs to be a common 3-sequence at the end of the first sequence and at the beginning of the second sequence. In this case, the common 3-sequence would be <{2}{3,4}>, where {2} is the last element in the first sequence and {3,4} is the common part between both sequences.

However, we cannot merge these two sequences because the required overlap does not exist. The first sequence ends with <{3,4}>, whereas the second starts with <{2}{3,4}>. For a merge to be valid, the ending of one sequence must be the exact starting sequence of the next, minus one item. Therefore, these two sequences cannot be merged to produce a valid 5-sequence as there is no proper overlapping sequence. The correct merge would involve sequences such as <{1,2}{3,4}{5}> and <{2}{3,4}{5}>, where <{3,4}{5}> overlaps.

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