Kato's log ll-adic monodromy-weight conjecture

Let X\overset{\circ}{X} be the underlying scheme of a proper SNCL scheme over κ\kappa, and let

N ⁣:Hketq(X1l,Ql)Hketq(X1l,Ql)(1)N\colon H^q_{\rm ket}(\overline{X}_{\frac{1}{l^{\infty}}},{\mathbb Q}_l)\longrightarrow H^q_{\rm ket}(\overline{X}_{\frac{1}{l^{\infty}}},{\mathbb Q}_l)(-1)

be the ll-adic monodromy operator. Let PP denote the filtration induced by the weight spectral sequence.

Kato's log ll-adic monodromy-weight conjecture. If X\overset{\circ}{X} is projective over κ\kappa, then, for every eZ1e\in{\mathbb Z}_{\geq 1}, NN induces an isomorphism

Ne ⁣:grq+ePHketq(X1l,Ql)grqePHketq(X1l,Ql)(e).N^e\colon {\rm gr}_{q+e}^P H^q_{\rm ket}(\overline{X}_{\frac{1}{l^{\infty}}},{\mathbb Q}_l)\overset{\sim}{\longrightarrow}{\rm gr}_{q-e}^P H^q_{\rm ket}(\overline{X}_{\frac{1}{l^{\infty}}},{\mathbb Q}_l)(-e).

This is a log ll-adic analogue of the monodromy-weight conjecture: it predicts that the monodromy operator satisfies hard Lefschetz-type isomorphisms on the graded pieces of the weight filtration. The source records this as Kato's conjecture; no resolution status is supplied here.

Sources & referencesView supporting material

Primary source

Yukiyoshi Nakkajima, “The l-adic bifiltered El Zein-Steenbrink-Zucker complex of a proper SNCL scheme with a relative SNCD”, arXiv:2504.00201 (2026).

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