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キーワード:
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要旨:
We consider the following combinatorial problem. We are given three strings s, t, and t'of length L over some fixed finite alphabet and an integer m that is polylogarithmic inL. We have a symmetric relation on substrings of constant length that specifies whichsubstrings are allowed to be replaced with each other. Let Δ(n) denote the differencebetween the numbers of possibilities to obtain t from s, and t' from s after n ∈ Nreplacements. The problem is to determine the sign of Δ(m). As promises we have agap condition and a growth condition. The former states that |Δ(m)| ≥ εcm where ε isinverse polylogarithmic in L and c > 0 is a constant. The latter is given by Δ(n) ≤ cnfor all n. We show that this problem is PromiseBQP-complete, i.e., it represents theclass of problems that can be solved efficiently on a quantum computer.