{ "id": "1807.01153", "version": "v1", "published": "2018-07-03T13:21:19.000Z", "updated": "2018-07-03T13:21:19.000Z", "title": "On a resolution of singularities with two strata", "authors": [ "Vincenzo Di Gennaro", "Davide Franco" ], "comment": "19 pages, no figures", "categories": [ "math.AG" ], "abstract": "Let $X$ be a complex, irreducible, quasi-projective variety, and $\\pi:\\widetilde X\\to X$ a resolution of singularities of $X$. Assume that the singular locus ${\\text{Sing}}(X)$ of $X$ is smooth, that the induced map $\\pi^{-1}({\\text{Sing}}(X))\\to {\\text{Sing}}(X)$ is a smooth fibration admitting a cohomology extension of the fiber, and that $\\pi^{-1}({\\text{Sing}}(X))$ has a negative normal bundle in $\\widetilde X$. We present a very short and explicit proof of the Decomposition Theorem for $\\pi$, providing a way to compute the intersection cohomology of $X$ by means of the cohomology of $\\widetilde X$ and of $\\pi^{-1}({\\text{Sing}}(X))$. Our result applies to special Schubert varieties with two strata, even if $\\pi$ is non-small. And to certain hypersurfaces of $\\mathbb P^5$ with one-dimensional singular locus.", "revisions": [ { "version": "v1", "updated": "2018-07-03T13:21:19.000Z" } ], "analyses": { "subjects": [ "14B05", "14E15", "14F05", "14F43", "14F45", "14M15", "32S20", "32S60", "58K15" ], "keywords": [ "resolution", "singularities", "one-dimensional singular locus", "special schubert varieties", "cohomology extension" ], "note": { "typesetting": "TeX", "pages": 19, "language": "en", "license": "arXiv", "status": "editable" } } }