# Variation of Hodge structure

A variation of Hodge structure of weight on a complex manifold is a couple where is a locally constant sheaf of finitely-generated Abelian groups on , and is a finite decreasing filtration of by holomorphic subbundles, subject to the following conditions: i) the flat connection on defined by , for , local sections of and , respectively, satisfies (Griffiths' transversality); ii) for each , the pair is a Hodge structure of weight .

A polarization of a variation of Hodge structure is a flat bilinear form which induces a polarization of the Hodge structure for each . Similar notions exist for replaced by or , [a2]. If is a proper smooth morphism of algebraic varieties over , then is the underlying local system of a polarizable variation of Hodge structure on . By a result of A. Borel, for a polarized variation of Hodge structure on a complex manifold of the form , where is compact and is a divisor with normal crossings, the monodromy around each local component of is quasi-unipotent [a3] (monodromy theorem). A polarized variation of Hodge structure over gives rise to a holomorphic period mapping from to a classifying space of Hodge structures (see Period mapping).

If with a compact Kähler manifold and a divisor with normal crossings on , then for a polarized variation of Hodge structure on , the sheaf has a minimal extension to a perverse sheaf on and carries a pure Hodge structure [a4]–[a6]. In fact, is part of a polarized Hodge module [a7]. Generalizations are the notions of variation of mixed Hodge structure [a8], [a9] and mixed Hodge module [a10].

#### References

[a1a] | P. Griffiths, "Periods of integrals on algebraic manifolds I" Amer. J. Math. , 90 (1968) pp. 568–626 MR0229641 Zbl 0169.52303 |

[a1b] | P. Griffiths, "Periods of integrals on algebraic manifolds II" Amer. J. Math. , 90 (1968) pp. 808–865 MR0233825 Zbl 0183.25501 |

[a1c] | P. Griffiths, "Periods of integrals on algebraic manifolds III" Publ. Math. IHES , 38 (1970) pp. 228–296 MR0282990 Zbl 0212.53503 |

[a2] | P. Deligne, "Travaux de Griffiths" , Sem. Bourbaki Exp. 376 , Lect. notes in math. , 180 , Springer (1970) pp. 213–235 Zbl 0208.48601 |

[a3] | W. Schmid, "Variation of Hodge structure: the singularities of the period mapping" Invent. Math. , 22 (1973) pp. 211–319 MR0382272 Zbl 0278.14003 |

[a4] | E. Cattani, A. Kaplan, W. Schmid, " and intersection cohomologies for a polarizable variation of Hodge structure" Invent. Math. , 87 (1987) pp. 217–252 MR870728 Zbl 0611.14006 |

[a5] | M. Kashiwara, T. Kawai, "The Poincaré lemma for variations of polarized Hodge structures" Publ. R.I.M.S. Kyoto Univ. , 23 (1987) pp. 345–407 MR0890924 |

[a6] | S. Zucker, "Hodge theory with degenerating coefficients: -cohomology in the Poincaré metric" Ann. of Math. , 109 (1979) pp. 415–476 MR534758 |

[a7] | M. Saito, "Modules de Hodge polarisables" Publ. R.I.M.S. Kyoto Univ. , 24 (1988) pp. 849–995 MR1000123 Zbl 0691.14007 |

[a8] | J. Steenbrink, S. Zucker, "Variation of mixed Hodge structure, I" Invent. Math. , 80 (1985) pp. 489–542 MR0791673 MR0791674 Zbl 0626.14007 |

[a9] | M. Kashiwara, "A study of a variation of mixed Hodge structure" Publ. R.I.M.S. Kyoto Univ. , 22 (1986) pp. 991–1024 MR866665 Zbl 0621.14007 |

[a10] | M. Saito, "Mixed Hodge modules" Publ. R.I.M.S. Kyoto Univ. , 26 (1990) pp. 221–333 MR1047741 MR1047415 Zbl 0727.14004 Zbl 0726.14007 |

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Variation of Hodge structure.

*Encyclopedia of Mathematics.*URL: http://www.encyclopediaofmath.org/index.php?title=Variation_of_Hodge_structure&oldid=24589