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arXiv · 1710.03623

Near-misses in Wilf's conjecture

Shalom Eliahou·Jean Fromentin
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Abstract

Let S $\subseteq$ N be a numerical semigroup with multiplicity m, conductor c and minimal generating set P. Let L = S $\cap$ [0, c -- 1] and W(S) = |P||L| -- c. In 1978, Herbert Wilf asked whether W(S) $\ge$ 0 always holds, a question known as Wilf's conjecture and open since then. A related number W0(S), satisfying W0(S) $\le$ W(S), has recently been introduced. We say that S is a near-miss in Wilf's conjecture if W0(S) < 0. Near-misses are very rare. Here we construct infinite families of them, with c = 4m and W0(S) arbitrarily small, and we show that the members of these families still satisfy Wilf's conjecture.

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Shalom Eliahou, Jean Fromentin. 2017-10-10. Near-misses in Wilf's conjecture. https://doi.org/10.1007/s00233-018-9926-5

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