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ii) follows from symmetry and multilinearity of the intersection product ([Ful98, Proposition 2.5]). For iii) we reduce first to the case where and have reduced special fibre. Let respectively be the canonical formal models with reduced special fibre as in 4. This construction is functorial and we obtain a commutative diagram
Assuming that we know the claim for reduced special fibres we obtain
So from now on assume that and have reduced special fibre. Let be an irreducible component of with corresponding Shilov point . Let be the preimages of under with corresponding irreducible components of . If is proper then clearly all the are proper. If on the other hand one of the is proper then is proper by [GW10, Proposition 12.59]. In this case we can use the projection formula to calculate:
As already mentioned in Definition 4.2, is finite outside a lower dimensional analytic subset. Hence we may apply equation (3) in the proof of [Gub98, Proposition 4.5] to see that the last term in the display equals .
On the other hand, if is an irreducible component of whose image is not an irreducible component of then its degree with respect to the line bundles is by the projection formula, as the image is of lower dimension. This proves iii).
For i) let be the decomposition into prime cycles. It is then enough to prove the claim for each and by definition of the measure we may hence assume that has irreducible and reduced generic fibre and reduced special fibre. Let be the set of all where is a proper irreducible component of with . Then is discrete as is an open neighbourhood of which does not contain any other points of . Furthermore is the union of all where runs over all irreducible components of and as all of these sets contain at most one point of and by paracompactness of , every has an open neighbourhood which does not intersect and hence is closed. By definition is of the desired form and its support is contained in the relative interior of over by Corollary A.4.
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