PPL 149 / 177 permanent IDsPrize Problem Ledger · PPLChecked 2026.07.26
Prize Problem LedgerIndependentPPL 149Shallit #17 · Factor universality of a finite language

Permanent problem IDPPL 149

Source-statedIndependentconjecture

Formal languages

Shallit #17 · Factor universality of a finite language

Determine the complexity of deciding whether every finite word occurs as a contiguous factor of a word in L*, for a finite list L.

automata theorytheoretical computer scienceformal languages
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The problem

Determine the complexity of deciding whether every finite word occurs as a contiguous factor of a word in L*, for a finite list L.

Open since2012historical source
Last checked2026.07.26Catalog verification
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Reward offers

Offer 01£25Jeffrey Shallit
Personal offer

Personal cash offer stated in Shallit’s official talk. The live talks page records subsequent updates, including a paid solution to one omitted problem; confirm claim procedure with the sponsor before relying on the award.

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Sources & reading