Hardcover | $48.00 Short | £39.95 | 350 pp. | 6 x 9 in | 8 color illus., 48 line drawings | August 2015 | ISBN: 9780262028844 eBook |$34.00 Short | August 2015 | ISBN: 9780262326797
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## Productivity and Reuse in Language

A Theory of Linguistic Computation and Storage

## Overview

Language allows us to express and comprehend an unbounded number of thoughts. This fundamental and much-celebrated property is made possible by a division of labor between a large inventory of stored items (e.g., affixes, words, idioms) and a computational system that productively combines these stored units on the fly to create a potentially unlimited array of new expressions. A language learner must discover a language’s productive, reusable units and determine which computational processes can give rise to new expressions. But how does the learner differentiate between the reusable, generalizable units (for example, the affix -ness, as in coolness, orderliness, cheapness) and apparent units that do not actually generalize in practice (for example, -th, as in warmth but not coolth)? In this book, Timothy O’Donnell proposes a formal computational model, Fragment Grammars, to answer these questions. This model treats productivity and reuse as the target of inference in a probabilistic framework, asking how an optimal agent can make use of the distribution of forms in the linguistic input to learn the distribution of productive word-formation processes and reusable units in a given language.

O’Donnell compares this model to a number of other theoretical and mathematical models, applying them to the English past tense and English derivational morphology, and showing that Fragment Grammars unifies a number of superficially distinct empirical phenomena in these domains and justifies certain seemingly ad hoc assumptions in earlier theories.

Timothy J. O’Donnell is a Postdoctoral Fellow in the Brain and Cognitive Sciences Department at MIT.

## Endorsements

“The trade-off between memory and creative combination is perhaps the fundamental issue in the understanding of language. Focusing on a domain that has long served as a proving ground for theories on this issue, Timothy O’Donnell not only documents the phenomena of productivity and reuse in greater richness than any previous analysis, but lays out a set of powerful and original ideas to explain them. This thoughtful and creative book is a landmark on this fundamental issue.”
Steven Pinker, Johnstone Family Professor of Psychology, Harvard University, and author of The Language Instinct and Learnability and Cognition
“In this groundbreaking book, Timothy O’Donnell portrays the structure of English words as an intricate dance between storage and computation. Knitting together the best of theoretical, computational, and experimental approaches to word structure, he builds an explicit model that yields real insights into how people store and create words.”
Mark Aronoff, Stony Brook University, author of Word Formation in Generative Grammar and Morphology by Itself
“O’Donnell addresses the problem of modeling English morphology in adult performance and child language acquisition, using a probabilistic ‘memo-izing’ functional programming language. The book combines a strong focus on open linguistic and cognitive problems with a deep understanding of machine learning and computational linguistic methods. Researchers in all of these fields will want to read this book.”
Mark Steedman, Professor of Cognitive Science, School of Informatics, University of Edinburgh
“Conceptually compelling. O’Donnell's book is the most rigorous treatment of morphological productivity since Baayen.”
Jennifer Hay, Professor in Linguistics, University of Canterbury
“Fragment grammars constitute the most compelling formal proposal yet for the gradient between combinatoriality and idiosyncrasy in human language. Productive computation and reuse are two paths to observed form, and the learner must infer the optimal balance between the two. O'Donnell’s models set a high bar for analyses of morphological productivity—and beyond—in years to come.”
Roger Levy, Associate Professor of Linguistics, University of California, San Diego