abstract a mountain glacier, when it occupies a river valley, immediately begins to change the cross-section and profile of that valley. river valleys in mountain areas tends to have v-shaped profiles. glaciers work to widen as well as deepen their valleys and the typical cross-section of a glacial valley is u-shaped. the u-shaped glacial valley is one of the most characteristic of glacial land...

(1999). "Regressions" ("u"-shaped learning) in the acquisition of prosodic structure. This paper addresses learning of constraint rankings by children. We argue that constraint demotion cannot account for all developmental patterns observed in child phonology. Learning algorithms that allow for constraint promotion fare better, but some still cannot account for all developmental changes. Child ...

It is generally believed that job satisfaction increases linearly with age. However, there are persuasive arguments, and some empirical evidence, that the relationship is Ushaped, declining from a moderate level in the early years of employment and then increasing steadily up to retirement. This paper investigates that relationship, using survey responses from a large sample of British employee...

U-shaped learning behaviour in cognitive development involves learning, unlearning and relearning. It occurs, for example, in learning irregular verbs. The prior cognitive science literature is occupied with how humans do it, for example, general rules versus tables of exceptions. This paper is mostly concerned with whether Ushaped learning behaviour may be necessary in the abstract mathematica...