Both environmental quality and health care expenditure are determinants of health and life expectancy, but the support for them appears to be different according to the electors' age, with a relatively larger support for health expenditure among the elderly as it is generally effective on a...

We study different extended formulations for the set (formule) in order to tackle the feasibility problem for the set (formule). Here the goal is not to find an improved polyhedral relaxation of conv(X+), but rather to reformulate in such a way that the new variables introduced provide good...