  In this paper we present web-liver, a rule-based system for decision support
in the medical domain, focusing on its application in a liver transplantation
unit for implementing policies for donor-patient matching. The rule-based
system is built on top of an interpreter for logic programs with partial
functions, called lppf, that extends the paradigm of Answer Set Programming
(ASP) adding two main features: (1) the inclusion of partial functions and (2)
the computation of causal explanations for the obtained solutions. The final
goal of web-liver is assisting the medical experts in the design of new
donor-patient matching policies that take into account not only the patient
severity but also the transplantation utility. As an example, we illustrate the
tool behaviour with a set of rules that implement the utility index called
SOFT.
