Example 5.26 . [02TP]
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Example 5.26.
Let be a complete fan in and the
corresponding toric variety. Recall the description of the
projective space as a toric variety
given in Example
4.3.
Let be a linear map such that, for each there
exist with . Let . Then we have an equivariant morphism
. Consider the support
function on . Then
. Write
,
and . Thus .
Set for the affine map.
Let be
the metric on induced by the canonical metric of
and let be the function
associated to it by Proposition 5.16. By Proposition 5.24,
. This is a piecewise affine concave function on
with that can be made explicit as follows.
Let be the standard basis of and let
be the dual basis. Write
and
.
Then
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