The rank of étale cohomology of varieties over -adic or number fields
We consider a short sequence of hermitian vector bundles on some arithmetic variety. Assuming that this sequence is exact on the generic fiber we prove that the alternated sum of the arithmetic Chern characters of these bundles is the sum of two terms, namely the secondary Bott Chern class of the sequence and its Chern character with support on the finite fibers. Next, we compute these classes in the situation encountered by the second author when proving a “Kodaira vanishing theorem”...
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