Stuckardt, Roland

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Mitkov, Ruslan, ed. (2003) The Oxford Handbook of Computational Linguistics, Oxford University Press.  Announced at http://linguistlist.org/issues/14/14-567.html   Roland Stuckardt, Johann Wolfgang Goethe University Frankfurt am Main, Germany  DESCRIPTION OF THE BOOK  The  edited  collection  under  review,  the  Oxford  Handbook  of  Computational  Linguistics (OHCL), belongs to the Oxford Handbooks series, which, according to the publisher, aims at providing „DQDXWKRULWDWLYHDQGVWDWHRIWKHDUWVXUYH\RIFXUUHQWWKLQNLQJDQGUHVHDUFK“ in particular subject areas. According to the editor, the OHCL addresses university researchers, teachers,  and  students  in  the  fields  of  Computational  Linguistics,  Computer  Science  and Linguistics,  as  well  as  professionals  such  as  industrial  researchers,  executives,  software engineers, and translators.  The book consists of thirty-eight chapters authored by fifty experts from all over the world, and  a  preface  by  Martin  Kay  with  a  brief  description  of  the  history  of  the  discipline  of Computational  Linguistics  (CL).  Each  chapter  covers  a  particular  topic  of  CL.  Chapter lengths vary between eleven and twenty-nine pages, with the majority of chapters comprising between fifteen and twenty pages. Access to the individual chapters is facilitated by abstracts. Each chapter includes a local list of bibliographic references, hints at further reading, and pointers (in particular, URLs) to relevant resources (software, corpora etc.).  The OHCL is divided into three parts, which are intended to reflect a natural progression from theory to practice.  Part I, “)XQGDPHQWDOV”, considers the issues typically covered by an introductory text on general linguistics, corresponding to the various levels of linguistic abstraction: 1. Phonology, 2. Morphology, 3. Lexicography, 4. Syntax, 5. Semantics, 6. Discourse, and 7. Pragmatics and Dialogue. However, the topics are discussed from a computational perspective to develop an  understanding  of  the  specific  problems  to  be  solved  before  a  respective  software technology can be implemented. Two further chapters, 8. Formal Grammars and Languages, and  9. Complexity,  provide  relevant  background  material  of mathematical  linguistics and theoretical computer science, covering, in particular, the fundamentals of automata theory, formal languages, and computational complexity.  Part II, “3URFHVVHV0HWKRGVDQG5HVRXUFHV”, takes the computation-oriented discussion of the linguistic and mathematical fundamentals in part I as the point of departure. The following detailed  description  of  the  basic  stages  of  text  and  speech  processing  and  the  employed methods, resources, and formalisms goes one step ahead towards automatic natural language processing  (NLP).  Eight  chapters  deal  with  specific  problems  of  processing  written  and spoken language: 10. Text Segmentation, 11. Part-of-Speech Tagging, 12. Parsing, 13. Word-Sense  Disambiguation  14.  Anaphora  Resolution,  15.  Natural  Language  Generation,  16. Speech Recognition, and 17. Text-to-Speech Synthesis. Another nine chapters describe the most important general methods, resources, and formalisms employed in these processing stages:  18.  Finite-State  Technology,  19.  Statistical  Methods,  20.  Machine  Learning,  21. Lexical Knowledge Acquisition, 22. Evaluation, 23. Sublanguages and Controlled Languages, 24. Corpus Linguistics, 25. Ontologies, and 26 Tree-Adjoining Grammars.  Part III, “$SSOLFDWLRQV”, focuses on the application of NLP technology for solving real world problems, proceeding from the description of the NLP base technology that is provided in part II.  Part  III  comprises  twelve  chapters:  27.  Machine  Translation:  General  Overview,  28. Machine  Translation:  Latest  Developments,  29.  Information  Retrieval,  30.  Information Extraction,  31.  Question  Answering,  32.  Text  Summarization,  33.  Term  Extraction  and Automatic Indexing, 34. Text Data Mining, 35. Natural Language Interaction, 36. Natural Language  in  Multimodal  and  Multimedia  Systems,  37.  Natural  Language  Processing  in Computer-Assisted  Language  Learning,  and  38.  Multilingual  On-Line  Natural  Language Processing.     In addition, the OHCL provides a list of commonly used acronyms and a glossary with brief definitions of about sixhundred key terms of CL and NLP. There are two general indexes: one by subject, and one by author/person.  CRITICAL EVALUATION  It would be beyond the scope of this review to provide a detailed evaluation of each of the thirty-eight chapters. Thus, the OHCL will be commented on at a general level. To some specific subjects it will be looked at in detail. The above description clearly shows that the OHCL covers all main topics of CL. It deals with the whole range of text, speech, and dialogue processing, and discusses issues of text and speech analysis as well as generation. The OHCL is unique in that it bridges between the linguistic fundamentals (as provided in part I), the respective software base technology (as described  in  part  II),  and  possible  applications  (as  discussed  in  part  III).  As  such  it complements  the  recent  textbook  by  Jurafsky  and  Martin  (2000),  which  focuses  on  the algorithmic, mathematical, and engineering aspects of NLP. Another positive aspect is the inclusion of brief and quite comprehensive surveys of the most central methods, resources, and formalisms, such as machine learning, statistics, finite-state technology, and corpora.  The general organization of the handbook is excellent. In many cases, multi-authored volumes consist  of  collections  of  more  or  less  loosely  connected  articles.  Regarding  the  OHCL, editorial efforts concerning the overall coherence have been highly successful, resulting in self-contained chapters that provide a large number of useful cross-references that foster the connectivity of the material. Coherence and general accessibility are enhanced by the uniform style of presentation, which enables the reader to quickly access the relevant resources and further readings without skimming through the whole body of text.   Content quality and actuality of the individual chapters are generally high, fostered by the selection of authors that are world-leading experts with extensive research experience on the respective topics. However, the assignment of multiple authors also entails a certain variance in the formal (organizational and presentational) quality of the individual contributions and, more importantly, in the accessibility for different types of readers. It goes without saying that tight  page  limits  always  involve  a  trade-off  between  coverage  on  one  and  verbosity  and readability on the other hand. Regarding the OHCL, with respect to both accessibility and formal quality, the difference between the individual articles is considerable, which may only partly be attributed to the varying degree of complexity of the issues covered. Beginning  with  the  positive  side  of  the  gamut,  the  majority  of  chapters  is  of  high organizational  and  presentational  quality,  and  accessible,  with  reasonable  efforts,  for advanced students, scientists, and professionals with moderate previous knowledge of CL, NLP, or Linguistics. Among the many excellently written chapters are: 2. Morphology, 3. Lexicography, 7. Pragmatics and Dialogue, 10. Text Segmentation, 15. Natural Language Generation,  25.  Ontologies,    27.  Machine  Translation:  General  Overview,  28.  Machine Translation:  Latest  Developments,  29.  Information  Retrieval,  34.  Text  Data  Mining,  35. Natural Language Interaction, 37. NLP in Computer-Assisted Language Learning.     However, there is also room for further improvement. In part I, “)XQGDPHQWDOV”, for instance, the strong direction of chapter 2 (Morphology) towards computational issues is in line with the computational perspective to be assumed. Some other articles, however, are to a lesser extent, such as the overall excellent chapter 5 on computational semantics, which could be further enhanced by an assessment of the general computational feasibility of the construction of  compositional-semantic  descriptions,  their  expected  coverage,  and  their  potential contribution  to  robust  NLP.  More  importantly,  the  presentation  and  organization  of  the material  covered  by  chapters  8  (Formal  Grammars  and  Languages)  and  9  (Complexity) should be revised. While these articles are useful references for researchers with previous knowledge, their presentation may be in parts too dense for an audience unfamiliar with these rather mathematical issues. The author of the last-mentioned chapter himself admits: “)RUDWUXHXQGHUVWDQGLQJRIFRPSOH[LW\LWLVEHVWWRUHDGDVHULRXVDOJRULWKPVERRN>«@” (page 196). Since the topics covered in these two chapters are highly related, it may be reasonable to integrate them into a single chapter of forty to fifty pages. To enhance the coherence of this rather  formal  subject  matter  with  the  rest  of  the  book,  the  important  discussion  of  its implications for practical issues of NLP may be expanded; the respective material, which is currently  scattered about  various subsections  (e.g., 9.2.6 and  9.3.8),  should be put into a dedicated section.  Regarding part II, “3URFHVVHV0HWKRGVDQG5HVRXUFHV”, parts of the generally well-written chapter 16 on speech recognition may be considered as quite difficult to access.Section 16.2 (Acoustic  Parameterization  and  Modeling)  refers  to  advanced  technical  notions  and presupposes a quite high amount of previous knowledge. On the other hand, it misses out some fundamentals, e.g. the notion of formants, which play a central role in the analysis of waveforms, and which are not included in the glossary either (cf. Jurafsky and Martin (2000), which provides a more extensive discussion of this topic). However, the other sections of this chapter are readily accessible without expert knowledge; in particular, the discussion of the performance of state-of-the-art speech recognition technology is excellent.  Regarding part III, “$SSOLFDWLRQV´, chapter 31 on question answering might be, to a certain extent, enhanced. While this article is logically structured and well organized, some parts of the  presentation  may  be  perceived  as  too  dense,  particularly  section  31.7  on  answer extraction. The details on training a perceptron, in particular the formula for the computation of a relative comparison score and the empirically determined weights and threshold values, are of little value to a reader interested in the fundamentals of answer extraction. Instead, more room  should be  given  to the discussion of  the  principal ideas  of answer extraction methods, perhaps focusing on the two most promising approaches and referring the reader to the literature for further technical details.  There is an additional topic further editions of the OHCL should include: discourse parsing. Fostered in large parts by the seminal work of Marcu (2000), this subject area has made rapid progress in  the  last few years. A chapter  on algorithmic  approaches  to discourse parsing would neatly fit in the book and supplement the current edition’s single article on discourse in part II (14. Anaphora Resolution). As such, it would provide a natural link between chapter 6 on the linguistic fundamentals of discourse and important applications discussed in part III, in particular  text  summarization  (chapter  32,  which  explicitly  refers  to  Marcu’s    work). Moreover, part III might be enhanced if chapters on text categorization and internet search engines were included.  There  are  some  further  minor  content-related  issues.  Chapter  14  (Anaphora  Resolution) should  include  a  brief  discussion  of  the  intricacies  of  anaphor  and  ellipsis  resolution  in dialogue; this important issue is referred to in chapter 35 on natural language interaction. Chapter 20 on machine learning should include approaches of unsupervised learning, which receive increasing attention in NLP since supervised learning requires annotated corpora the gathering of which is, in general, expensive. Chapter 22 on the central topic of evaluation should be allotted more pages. Some practical examples of formal, corpus-based evaluation tasks would be helpful. Furthermore, the comparatively dense section 22.4 on the evaluation of  interactive  systems  should  include  more  details.  Chapter  30  on  information  extraction should  provide  more  pointers  to  concrete  systems,  including  an  overview  of  software technology  available  for  different  languages.  Finally,  chapter  35  on  natural  language interaction  should  include  a  discussion  on  the  emerging  dialogue  modeling  standard VoiceXML.   Two further marginal organizational issues: the table of contents should provide at least the section headings in addition to the chapter headings. Chapter 2 employs five different levels of section embedding; thisis inadequate with an article of only 23 pages.    CONCLUDING REMARKS  In accordance with the intentionsset out by the editor and the publisher, the OHCL provides a comprehensive high-quality survey of the theoretical fundamentals of CL and state-of-the-art NLP,  as  it  covers  the  base  technology,  the  underlying  methods,  and  a  wide  range  of application scenarios. Most chapters provide self-contained surveys of specific CL topics that are  adequate  reading  to  an  audience  with  moderate  previous knowledge,  ranging  from advanced  students  of  CL,  Linguistics,  and  Computer  Science  to  scientists  and  industrial researchers. While it neither substitutes introductory textbooks nor monographs on the issues under discussion, it is an excellent reference book that provides a wealth of information and enables  the  experienced  reader  to  quickly  enter  into  new  subject  areas  of  CL  and  NLP. Thanks to its unique structure, it neatly complements books that focus on the technological aspects of NLP such as the text of Jurafsky and Martin (2000). Whereas these authors provide more  thorough  descriptions  and  illustrations  of  algorithms,  the  particular  strengths  of  the OHCL are the comprehensive computation-oriented discussion of the fundamental linguistic issues and the broad coverage of NLP methods and resources. It thus extensively accounts for the theoretical and methodological backgrounds of CL and NLP.  A final note on pricing: the relatively high price of GBP 95.- (US$ 150.-) quoted by the publisher  may  put  off  many  potential  readers.  The  publisher  should  consider  issuing  a moderately priced student’s edition to make the OHCL affordable to the wide audience it definitely deserves.  REFERENCES  Daniel  Jurafsky  and  James  H.  Martin  (2000).  6SHHFK DQG /DQJXDJH 3URFHVVLQJ $Q,QWURGXFWLRQ WR 1DWXUDO /DQJXDJH 3URFHVVLQJ &RPSXWDWLRQDO /LQJXLVWLFV DQG 6SHHFK5HFRJQLWLRQ Prentice Hall, Upper Saddle River, NJ.  Daniel Marcu (2000). 7KH7KHRU\DQG3UDFWLFHRI'LVFRXUVH3DUVLQJDQG6XPPDUL]DWLRQ. The MIT Press, Cambridge, MA.  ABOUT THE REVIEWER  Roland  Stuckardt  works  as  a  postdoctoral  researcher  and  consultant  in  the  fields  of Computational Linguistics and Natural Language Engineering. He received his Ph.D. in 2000 from the University of Frankfurt am Main. His current research interests include anaphor resolution,  information  extraction,  text  summarization,  question  answering,  and  spoken dialogue systems. (web: http://www.stuckardt.de/)  

Mitkov, Ruslan, ed. (2003) The Oxford Handbook of Computational Linguistics, Oxford University Press : [review]

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