On the Infinite Dimensionality of the Middle $L^2$ Cohomology of Complex Domains
Author(s) -
Takeo Ohsawa
Publication year - 1989
Publication title -
publications of the research institute for mathematical sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.786
H-Index - 39
eISSN - 1663-4926
pISSN - 0034-5318
DOI - 10.2977/prims/1195173354
Subject(s) - mathematics , cohomology , bounded function , pure mathematics , holomorphic function , manifold (fluid mechanics) , complex manifold , invariant (physics) , stein manifold , degree (music) , boundary (topology) , dimension (graph theory) , domain (mathematical analysis) , mathematical analysis , acoustics , mechanical engineering , physics , engineering , mathematical physics
In 1983, H. Donnelly and C. Fefferman [3] discovered a strikingly new phenomenon in complex analysis by establishing a vanishing theorem for the invariant L cohomology. According to their result, for any strictly pseudoconvex bounded domain D in a Stein manifold of dimension n, the L cohomology groups of D vanish except for that of the middle degree n. Their proof is based on a rather original estimate of H. Donnelly and F. Xavier [4] which may well be called the Hardy's inequality on manifolds. As for this new estimate, K. Takegoshi and the author [10] noticed that it is a direct consequence of Jacobi's identity, and applied it later to show an extension theorem for L holomorphic functions (cf. [9]). It has applications to the Hodge theory on singular complex spaces, too. (cf. [7] and [8]). As for the L cohomology in the middle degree, it was also shown in [3] that their (p, q) components are all infinite dimensional. Compared to the vanishing theorem, the basic reason for such infinite dimensionality seems to remain less transparent, although it is discussed under several different geometric situations (cf. [1], [6]). Therefore it might make sense to ask for a general geometric situation under which the infinite dimensionality is valid. The present paper is meant for that purpose. Let D be a domain in a connected complex manifold of dimension n. By definition, a regular boundary point of D is a point p e dD which admits a realvalued C°° function cp defined on a neighbourhood U B p such that dcp(p) ^ 0 and [/n D = {xeU;
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