{ "id": "0806.1461", "version": "v5", "published": "2008-06-09T13:47:41.000Z", "updated": "2008-09-29T15:20:32.000Z", "title": "Generalized Thomas hyperplane sections and relations between vanishing cycles", "authors": [ "Morihiko Saito" ], "comment": "14 pages", "categories": [ "math.AG" ], "abstract": "As is remarked by B. Totaro, R. Thomas essentially proved that the Hodge conjecture is inductively equivalent to the existence of a hyperplane section, called a generalized Thomas hyperplane section, such that the restriction to it of a given primitive Hodge class does not vanish. We study the relations between the vanishing cycles in the cohomology of a general fiber, and show that each relation between the vanishing cycles of type (0,0) with unipotent monodromy around a singular hyperplane section defines a primitive Hodge class such that this singular hyperplane section is a generalized Thomas hyperplane section if and only if the pairing between a given primitive Hodge class and some of the constructed primitive Hodge classes does not vanish. This is a generalization of a construction by P. Griffiths.", "revisions": [ { "version": "v5", "updated": "2008-09-29T15:20:32.000Z" } ], "analyses": { "subjects": [ "32S40" ], "keywords": [ "generalized thomas hyperplane section", "vanishing cycles", "primitive hodge class", "singular hyperplane section defines" ], "note": { "typesetting": "TeX", "pages": 14, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2008arXiv0806.1461S" } } }