Hello, I have a question, please.
As we know, we have horizontal and vertical database representation in the domain of sequential pattern mining. My specific question: Are database projection algorithms considered within the category of horizontal database representation or is it considered as a third category?
Thank you

Good morning,

An algorithm like PrefixSpan uses an horizontal database and do database projections. PrefixSpan is said to use a "pattern growth" approach.

For me, I categorize the algorithms as follows:

PrefixSpan: Horizontal database, pattern-growth, database projection, do a depth-first search
CM-SPADE and SPAM: Vertical database encoded as bitvectors, generate candidates, do a depth-first search
GSP: Vertical database, generate candidates, do a breadth first search
FreeSpan: patterngrowth, horizontal database I think... and probably also do database projection but I dont remember
and there are other algorithms.
...

If you did not read my survey of sequential pattern mining, it gives some good overview.

Best regards,

Good morning,

Thank you for this explanation.

I believe that you meant to mention that GSP uses a horizontal database representation as it is mentioned in your survey.

Best regards,

Hi, you are welcome. Yes, I think I made a mistake ;-)

Best regards,

Philippe