**Description
|** Some Portuguese Public-Private Partnerships (PPP)
contracts in the road sector include a set of mathematical formulas
designed to evaluate the annual rents paid to the private partners.
Some of those formulas have peculiar characteristics, providing
interesting challenges for mathematical modelling research. Among them
there are denominators that may be zero, penalties with negative
values, sums of symmetric amounts and other bizarre features.

In this work we will try to investigate those formulas, describe them and build an alternative model for the underlying sections on the PPP contracts.

**Coordinator
|** José M. A. Matos, ISEP/LEMA and CMUP.