Introduction to Computational Linguistics · requires all steps relevant to linguistic analysis of input sentences and linguistic generation of output sentences hence, machine translation

Introduction to ComputationalLinguistics

Frank Richter

[email protected].

Seminar fur Sprachwissenschaft

Eberhard-Karls-Universit at Tubingen

Germany

Intro to CL – WS 2006/7 – p.1

Central Goal of the Field

build psychologically adequate models of humanlanguage processing capabilities on the basis ofknowledge about the way in which humans acquire,store, and process language.

build functionally correct models of human languageprocessing capabilities on the basis of knowledge aboutthe world and about language elicited from people andstored in the system.


Application Areas

machine translation

speech recognition

speech synthesis

man-machine interfaces


Application Areas

intelligent word processing: spelling correction,grammar correction

document managementfind relevant documents in collectionsestablish authorship of documentscatch plagiarismextract information from documentsclassify documentssummarize documentssummarize document collections


A bit of Philosophy of Science

Theory:A set of statements that determine the format andsemantics of descriptions of phenomena in the purviewof the theory

Methodology:An effective theory comes with an explicit methodologyfor acquiring these descriptions

Application:A theory associated with a methodology can be appliedto tasks for which the methodology is appropriate.


Scientific Strategies

Method Oriented Approach:devise or import a tool, a procedure or a formalism,apply it to a task and develop it further. Then(optionally) see whether it works for additional tasks

Task oriented Approach:select a task; devise or import a method or severalmethods for its solution; integrate the methods asrequired to improve performance.


Machine Translation

What makes Machine Translation an important applicationarea to study:

historically first application area, and for at least adecade the only application area, of computationallinguistics


Machine Translation



requires all steps relevant to linguistic analysis of inputsentences and linguistic generation of output sentences


Machine Translation



requires all steps relevant to linguistic analysis of inputsentences and linguistic generation of output sentences

hence, machine translation is scientifically one of themost challenging and most comprehensive tasks incomputational linguistics


The Purposes of Translation

Information Acquisition:e.g. Gather information on scientific articles ornewspapers written in a foreign language.




Information Dissemination:e.g. Translation of technical manuals, legal texts,weather reports, etc.




Information Dissemination:e.g. Translation of technical manuals, legal texts,weather reports, etc.

Literary Translation:e.g. Translation of novels, poems, etc.


Relating Translation Purposes to MT

Information Acquisition:involves translation from a foreign to a nativelanguage



Information Acquisition:involves translation from a foreign to a nativelanguagetypically used by non-linguists with little or nolinguistic competence in the source language



Information Acquisition:involves translation from a foreign to a nativelanguagetypically used by non-linguists with little or nolinguistic competence in the source languagepre-processing of the input not feasible due to lack oflinguistic competence by the user in the sourcelanguage



Information Acquisition:involves translation from a foreign to a nativelanguagetypically used by non-linguists with little or nolinguistic competence in the source languagepre-processing of the input not feasible due to lack oflinguistic competence by the user in the sourcelanguagemay require special-purpose lexica



Information Acquisition:involves translation from a foreign to a nativelanguagetypically used by non-linguists with little or nolinguistic competence in the source languagepre-processing of the input not feasible due to lack oflinguistic competence by the user in the sourcelanguagemay require special-purpose lexicalow-quality translation is tolerable


Relating Translation Purposes to MT(2)

Information Dissemination:involves translation from a native to a foreignlanguage



Information Dissemination:involves translation from a native to a foreignlanguagepre- and post-processing of the input feasible due tolinguistic competence by the translator in the sourcelanguage



Information Dissemination:involves translation from a native to a foreignlanguagepre- and post-processing of the input feasible due tolinguistic competence by the translator in the sourcelanguagemay involve sublanguage with restricted vocabulary;e.g. translation of weather reports



Information Dissemination:involves translation from a native to a foreignlanguagepre- and post-processing of the input feasible due tolinguistic competence by the translator in the sourcelanguagemay involve sublanguage with restricted vocabulary;e.g. translation of weather reportsoften involves special terminologies stored in aterminology database; e.g. for translation oftechnical manuals



Information Dissemination:involves translation from a native to a foreignlanguagepre- and post-processing of the input feasible due tolinguistic competence by the translator in the sourcelanguagemay involve sublanguage with restricted vocabulary;e.g. translation of weather reportsoften involves special terminologies stored in aterminology database; e.g. for translation oftechnical manualspurely human translation for such tasks can betime-consuming, inconsistent, or tedious.



Literary Translationrequires stylistic elegance, often involvesmetaphorical and metonymic language



Literary Translationrequires stylistic elegance, often involvesmetaphorical and metonymic languageabundance of highly-trained human translators



Literary Translationrequires stylistic elegance, often involvesmetaphorical and metonymic languageabundance of highly-trained human translatorstask rarely performed by machine translation


What Makes Machine Translation Hard

Lexical Ambiguity



Lexical Ambiguity

Lexical Gaps



Lexical Ambiguity

Lexical Gaps

Syntactic Divergences between Source and TargetLanguage


Documents

Introduction to Computational Linguistics · requires all steps relevant to linguistic analysis of input sentences and linguistic generation of output sentences hence, machine translation