We study the mixed spectrum and vanishing cohomology for several classes of (isolated and nonisolated) hypersurface singularities, and how they contribute to the limiting mixed Hodge structure of a smoothing. Applications are given to several types of singularities arising in KSBA and GIT compactifications and mirror symmetry, including nodes, k-log-canonical singularities, singularities with Calabi-Yau tail, normal-crossing degenerations, slc surface singularities, and the J k,∞ series.
ContentsIntroduction Set-up and overview of results Structure of the paper Synopsis of Part I ([KL19]) Acknowledgement 1. Mixed spectra of isolated singularities 2. The quasi-homogeneous case 2.1. Weighted Fermat singularities and deformations 2.2. Nodes on odd-dimensional hypersurfaces 3. Singularities with Calabi-Yau tail 4. Isolated hypersurface singularities: birational invariants 5. Isolated hypersurface singularities: spectral combinatorics 5.1. Toric geometry approach 5.2. Brieskorn lattice approach 6. Sebastiani-Thom formula 6.1. Application to k-log-canonical singularities 7. Non-isolated singularities 7.1. Remarks on rational, du Bois, normal-crossing, and k-lc singularities 7.2. The SSS formula 7.3. Some non-isolated slc surface singularities 7.4. The J k,∞ series 7.5. Clemens-Schmid discrepancies for nodal total spaces References