Local closedness and finiteness conjectures for Kollár valuations

Let x?x\text{?} denote the klt singularity and let DD be a Q\mathbb{Q}-complement such that {x\} is the only lc center of (X,Δ+D)(X,\Delta+D). Write D(X,Δ+D)\mathcal{D}(X,\Delta+D) for the associated dual complex and DKV(X,Δ+D)\mathcal{D}^{\rm KV}(X,\Delta+D) for its locus of Kollár valuations. A rational triangulation is a triangulation whose vertices have rational coordinates, and a finite triangulation has finitely many simplices. A cell is realized in a Kollár model if it is represented by Kollár valuations on such a model.

Local closedness and finiteness conjectures. The locus DKV(X,Δ+D)\mathcal{D}^{\rm KV}(X,\Delta+D) satisfies all of the following:

  1. There is a rational triangulation of D(X,Δ+D)\mathcal{D}(X,\Delta+D) such that for each open simplex CC^{\circ}, DKV(X,Δ+D)C\mathcal{D}^{\rm KV}(X,\Delta+D)\cap C^{\circ} is open in its closure DKV(X,Δ+D)CC\overline{\mathcal{D}^{\rm KV}(X,\Delta+D)\cap C^{\circ}}\subset C^{\circ}.
  2. There is a rational triangulation of D(X,Δ+D)\mathcal{D}(X,\Delta+D) such that for each open simplex CC^{\circ}, DKV(X,Δ+D)CC\mathcal{D}^{\rm KV}(X,\Delta+D)\cap C^{\circ}\subset C^{\circ} is open.
  3. If D(X,Δ+D)=DKV(X,Δ+D)\mathcal{D}(X,\Delta+D)=\mathcal{D}^{\rm KV}(X,\Delta+D), then there is a finite triangulation of D(X,Δ+D)\mathcal{D}(X,\Delta+D) such that each simplex can be realized on a Kollár model.
  4. If CDKV(X,Δ+D)C\subseteq\mathcal{D}^{\rm KV}(X,\Delta+D) is a closed cell of D(X,Δ+D)\mathcal{D}(X,\Delta+D) after a triangulation given by a log resolution, then there is a finite triangulation C=i=1NCiC=\bigcup_{i=1}^{N}C_i such that each CiC_i is realized in a Kollár model.

These conjectures refine the known nonemptiness, local structure, and path connectedness results for the locus of Kollár valuations. The source does not provide evidence resolving any of the four assertions.

Sources & referencesView supporting material

Primary source

Yuchen Liu and Chenyang Xu, “A note on Kollár valuations”, arXiv:2406.00228 (2024).

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