Remark 4.83 . [02RY]
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Remark 4.83.
Let be a complete fan in and a virtual support function on . Let be a toric model of . Then, by Theorem 4.81, there exists a complete SCR polyhedral complex in with and a rational piecewise affine function on such that is an H-lattice function, and . Moreover, if is another toric model that gives the function , then both models are equivalent if and only if . Thus, to every toric model we have associated a rational piecewise affine function on such that . Two equivalent models give rise to the same function.
The converse is not true. Given a rational piecewise affine function , with , we can find a complete SCR polyhedral complex such that is piecewise affine on . But, in general does not agree with . What we can expect is that is a refinement of . Therefore the function gives us an equivalence class of toric models of . But may not determine an equivalence class of toric models of . In Corollary 5.43 in next section we will give a necessary condition for a function to define an equivalence class of toric models of and in Example 5.44 we will exhibit a function that does not satisfy this necessary condition. By contrast, as we will see in Theorem 4.97, the concave case is much more transparent.