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Abstract:

In the pandiagonal Latin Square problem, a square grid of size N needs to be filled with N types of objects, so that each column, row, and wrapped around diagonal (both up and down) contains an object of each type. This problem dates back to at least Euler. In its specification as a constraint satisfaction problem, one uses the all_different constraint. The known redundancy result about all_different constraints in the Latin Square problem is lifted to the pandiagonal Latin Square problem. This proof method's theoretical limits are established.