Fujita's log spectrum conjecture for pseudo-effective thresholds

Let (X,Δ)(X,\Delta) be a log smooth variety with Δ\Delta a reduced divisor. Let MM be an ample Cartier divisor on XX, and let pet(X,Δ;M)R0\operatorname{pet}(X,\Delta;M)\in\mathbb{R}_{\geq 0} be the pseudo-effective threshold of KX+ΔK_X+\Delta with respect to MM. Let PETn\operatorname{PET}_n be the set of all such thresholds for varieties of dimension nn. For SRS\subseteq\mathbb{R}, let lim1S\lim^1S be the set of accumulation points of SS, and define

limkS=lim1(limk1S)\lim^kS=\lim^1(\lim^{k-1}S)

for kNk\in\mathbb{N}.

Fujita's log spectrum conjecture. Under this notation,

limk(PETn)nk\lim^k(\operatorname{PET}_n)\leq n-k

for any positive integer knk\leq n.

The conjecture is an analogue for pseudo-effective thresholds of the conjecture on accumulation points of log canonical thresholds. The source notes that the related ACC conjecture for pseudo-effective thresholds has been proved in several settings, but gives no resolution status for this log spectrum conjecture.

Sources & referencesView supporting material

Primary source

Jingjun Han and Zhan Li, “On accumulation points of pseudo-effective thresholds”, arXiv:1812.04260 (2020).

Additional references

3 papers in this index state this conjecture (1997–2018). The statement above is taken from the most recent of them; the others are arXiv:1301.4967, arXiv:alg-geom/9712002.

Source: https://arxiv.org/abs/1812.04260 Fujita (1996), cited in the source as Fuj96

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