PPL 146 / 177 permanent IDsPrize Problem Ledger · PPLChecked 2026.07.26
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Prize Problem LedgerIndependentPPL 146Shallit #14 · Divisibility and automata

Permanent problem IDPPL 146

Source-statedIndependentconjecture

Formal languages

Shallit #14 · Divisibility and automata

Is it decidable whether a DFA over pairs of base-k digits accepts some pair of integers (x, y) with x dividing y?

automata theorytheoretical computer scienceformal languages
01

The problem

Is it decidable whether a DFA over pairs of base-k digits accepts some pair of integers (x, y) with x dividing y?

Open since2013historical source
Last checked2026.07.26Catalog verification
02

Reward offers

Offer 01£50Jeffrey 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.

Award source ↗Rules ↗
03

Sources & reading

2 unique reference linksSponsor’s official problem slides Claim or award rules
04

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