Superpermutation Almanac

Back to n = 9

W-0083

A superpermutation on 9 symbols, found by Jay Pantone. It ties W-0038, which was the record at the time.

Length
408,731
Repeated permutations
257
Received
Nov 6, 202623:02:15 UTC
Begins 012345678012345670812345670182345670128345670123845670123485670123458670123456870123456078123456071823456071283456071238…

Windows

408,723windows of 9 consecutive letters
=362,880distinct permutations
+257repeated permutations
+45,586windows that are not permutations

Detours by weight

A step is the move from one permutation in the superpermutation to the next permutation in it, and its weight is the number of letters added in that move. A detour starts at a step that differs from the next step of the recursive construction, and ends at the first permutation after that whose next step has weight 1. The weight of a detour is the number of letters added in it. After each detour, we consider the recursive construction to begin again from scratch at the permutation where the detour ends.

WeightDetours
10
22
31,513
44
54
639
74
80
90

How it was found

From the submitter

Found by a cold-start Gurobi MILP assembling recursive runs followed by maximal detours, using the detour patterns of rumstd's W-0038 plus all maximal weight-2 and weight-3 patterns. Allowed reset states were those of W-0038 together with first-pair and last-pair positional swaps; runs had at most 503 default steps, and at most two maximal weight-2 detours were permitted. The solver found this 408,731-letter tie with 257 repeated permutation occurrences and reported it optimal within that restricted family; no shorter word was found.

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