An ICALL writing support system tunable to varying levels of learner initiative Karin Harbusch 1 & Gerard Kempen 2,3 1 University of Koblenz-Landau, Koblenz, DE 2 Max Planck Institute for Psycholinguistics, Nijmegen, NL 3 Department of Psychology, Leiden University, NL

Motivation: Learning to write in L2 through a dialogue with a sentence generator COMPASSII prototype at work (based on the Performance Grammar (PG) formalism) Student-initiated feedback production in our L2-writing system COMPASSII Conclusions and future work Overview

Observation: Langugage lerners like to create and test their own sentences instead of being restricted to work with prepared text materials. Motivation (I): Why ICALL? ICALL solution: Apply Natural Language Processing (NLP) techniques. Parsing Generation

Motivation (II): Parsing-based ICALL-system After the student has typed a sentence, the parser evaluates it and provides feedback on the grammatical quality. Problems with producing fine-tuned feedback: The more errors a sentence contains, the less accurate the feedback, due to the many correction options in the parser. Ambiguities in the analysis process make it difficult to select appropriate feedback. Origin of parsing problems: Student and parser perform rather different tasks although they use the very same grammar rules. However, interpreting and applying the rules for production purposes is not the same thing as doing this for comprehension purposes.

In producing a written sentence, writer and generation system perform the same job, based on the same grammar rules. Motivation (III): Generation-based L2 learning So, let them do the job together. Let them inform and help each other while building a grammatically correct sentence that expresses the student’s communicative intention.

Students construct sentences in a dialogue via a graphical drag&drop user interface of a natural language generation system, which intervenes immediately when they try to build an ill-formed structure. Every construction step is commented with informative feedback that the student might study in more depth. Motivation (IV): Dialogue with the generator Learner-initiated grammar study based on fine-tuned informative feedback

NLP techniques deployed in the L2-writing system COMPASSII COMPASSII: COMbinatorial and Paraphrastic Assembly of Sentence Structure Feedback in COMPASSII is based on a natural-language sentence and paraphrase generator with a graphical drag&drop user interface. Performance Grammar (PG) formalism and paraphrase generation for PG

The student drags words into a workspace where their grammatical properties are displayed in the form of syntactic treelets as defined in our grammar formalism (Lexicalized Performance Grammar). System at work (L2 = German, L1 = English) Why Performance Grammar? During the construction process, Performance Grammar affords the flexibility to concentrate on any part of the linguistic structure, in any order. Learner-initiative

Performance Grammar (PG) is a fully lexicalized grammar that belongs to the family of tree substitution grammars and deploys disjunctive feature unification as its main structure building mechanism. It adheres to the ID/LP format and includes separate components generating the hierarchical and the linear structure of sentences. Flat constituent/dependency trees. Every node contains finegrained syntactic information of the form: syntactic feature = value (e.g. case = accusative). Nodes may share this information. Word order rules are decoupled from constituent/dependency information. Word order rules are based on the linguistic theory of topological fields During the construction process, Performance Grammar affords the flexibility to concentrate on any part of the linguistic structure, in any order.

The student drags words into a workspace where their grammatical properties are displayed in the form of syntactic treelets as defined in our grammar formalism (Lexicalized Performance Grammar). Lexicon window List of inflected word forms the students can select from

The student drags words into a workspace where their grammatical properties are displayed in the form of syntactic treelets as defined in our grammar formalism (Lexicalized Performance Grammar). Workspace window Student manipulates lexical treelets in the workspace

The student drags words into a workspace where their grammatical properties are displayed in the form of syntactic treelets as defined in our grammar formalism (Lexicalized Performance Grammar). Feedback window Communication window currently showing treelet information belonging to selected node in the workspace

In the workspace, the student can combine treelets by moving the root of one treelet to a foot of another treelet. In the generator, this triggers a unification process that evaluates the quality of the intended structure. Tree building in the workspace If the latter is licensed by the generator’s syntax, the tree grows and a larger phrase-structure tree is displayed. In case of licensing failure, the generator informs the student about the reason(s). This feedback follows directly from the unification requirements.

Tree composition via drag&drop

Feedback generation during the writing dialogue Each student action triggers detailed informative feedback (positive/negative). All feedback texts are attached to a PG treelet or to a word order rule, which can be inspected in more detail if desired. MAL-RULES extend the grammar to model frequently observed errors.

Conclusions COMPASSII system is a new sentence generation application.We deploy the paraphrase generator for PG which allows direct graphical manipulation of syntactic structures. COMPASSII supports students in producing diverse sentence structures on-line allowing them to focus on grammatical structure.

Future work (I) Feedback texts adapted to the grammatical knowledge of the student, Developing a real German course targeting some domain of constructions, e.g. word order in German clauses, for highschool students who are native speakers of English. Evaluation studies with such ICALL courses.

Future work (II) Teach coordinate elision in German Example of clausal coordination from the TIGER treebank: Monopole sollen geknackt werden und Märkte sollen getrennt werden ‘Monopolies should be shattered and markets split’ Monopole sollen geknackt werden und Märkte sollen getrennt werden ⌧ ⌧ ⌧⌧ COMPASSII subsystem of ELLEIPO: generates all possible elisions corpus frequences determine preferred choice

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For more information on the Performance Grammar formalism and COMPASSII see our websites: Ask us for a liveAsk us for a live demo here at CALL 2010!