Inversion of adjunction conjecture for foliations

Let XX be a normal variety, let F\mathcal F be a foliation on XX, let SS be a prime divisor on XX and let B0B \ge 0 be a Q\mathbb Q-divisor such that mSB=ε(S)m_SB = \varepsilon(S) and such that KF+BK_{\mathcal F}+B is Q\mathbb Q-Cartier. Let n ⁣:TSn\colon T \rightarrow S be the normalisation and define foliation adjunction by

n(KF+B)=KFT+BT.n^*(K_{\mathcal F}+B)=K_{\mathcal F_T}+B_T.

If (FT,BT)(\mathcal F_T,B_T) is log canonical, then (F,B)(\mathcal F,B) is log canonical in a neighbourhood of SS.

Inversion of adjunction. Log canonicity of the induced foliated pair on the normalisation of SS should imply log canonicity of the original foliated pair near SS.

This conjecture is closely related to the deformation conjecture for semi-log canonical foliation singularities and is motivated by inversion of adjunction in the birational study of pairs. The source presents it as an open conjecture.

Sources & referencesView supporting material

Primary source

Calum Spicer, Roberto Svaldi and Sebastian Velazquez, “On moduli of foliated surfaces”, arXiv:2511.13491 (2025).

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