Summing up over ALL path costs?

[Marlene S]

True or false: “A key operation in DTW is the summation of all path costs at each point in the grid.”?

What confuses me is the term “ALL” – would that imply the addition not only of subpaths that make up ONE path leading into the cell, but of all the possible (alternative paths)? Because the latter is false.

[Simon]

In DTW, there is no summing at all. We are only interested in the signal best path, and so take the minimum path cost at every grid point.

[Marlene S]

Yes, but to we do sum up over sub-paths that belong to the SAME (sub)path, leading into that node? Else how do we get the total path cost? And wouldn’t that be too greedy otherwise?

[Kurt A]

Every time a token moves, you’re updating its distance with a subcost, not recomputing the distance by summing up all past subcosts. The question’s referring to what happens at a junction with regard to all incoming tokens.

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