Reasoning Support for Risk Prediction and Prevention in Independent Living 29

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Table 9. Graph for Example 4

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Prevention In order to identify which feedback to provide, in which form and when, the reasoning component applies a set of rules we refer to as a *feedback* policy. A preliminary proposal for the application of a declarative policy description language to reason about feedback has been presented in (Mileo and Bisiani 2009). The basic idea is that a small set of well defined policy rules can be used to produce reactions of the system according to results of prediction. Since we refer to prevention as to those interventions that may keep health changes within safe boundaries, we concentrate on feedback provided as a result of predictions that identify worsening conditions.

The declarative policy language we propose admits different kinds of high-level rules that are then mapped into ASP. These rules make it possible to represent:

- results of prediction for a given item I identify a candidate form fi(X) for a feedback X according to the explanation path associated to the prediction (event-triggering rules);
- only one feedback form fi(X) among the triggered ones should be provided for the same feedback X (choice rules);