Directionality in cross-categorial derivations

What exactly is the relationship between verb hammer and noun hammer? Is one derived from other, are both a common source, how can we tell? This article provides an overview of recent generative approaches to derivational directionality reviews different kinds answers given such questions, considering diachrony synchrony deverbal nouns, deadjectival denominal verbs, similar forms. We critically survey main empirical points argued for in languages evaluate analyses that have been proposed. highlight where progress has made what open questions still remain, proposing formal accounts be seen as implementing two concrete processes, which term Affix Imposition Root Augmentation.