4 In Friedman’s policy framework, u* and r* are economic destinations, not policy rule inputs. Of course, I do not need to elaborate for this audience that the history of k-percent rules is that they were rarely tried, and when they were tried in the 1970s and the 1980s, they were found to work much better in theory than in practice.
5 Velocity relationships  3  See Friedman (1968, pp. 8–11). At roughly the same time, Phelps (1967) derived similar results using a formal economic model.