4.2 [035K]
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4.2
We will define some local invariants in . On an open affine neighbourhood , the point is given by a multiplicative seminorm on and we often write for . Dividing out the prime ideal , we get a multiplicative norm on the integral domain which extends to an absolute value on the quotient field of . The completion of this field is denoted by . It does not depend on the choice of and it may be also constructed analytically. The absolute value of is denoted by as it extends the given absolute value on . Note that the completed residue field of remains the same if we replace the ambient variety by the Zariski closure of in .
Let be the transcendence degree of the residue field of over . The quotient of the value group of by is a finitely generated abelian group and we denote its -rank by . Finally, we set . By [Be90], Proposition 9.1.3, we have for every open subset of .