“…Remark Some conditions, which guarantee that (A2) holds, can be found in the work of Panov . For instance, it is sufficient to assume that there exists a density function and ( d − 1) functions , such that - for any u , x > 0,
- the functions monotonically increase in u j for any fixed v , and moreover, for any j = 1,…,( d − 1) and any y > 0, the equation has a closed‐form solution with respect to u j ; we denote this solution by .
In fact, in this case, …”