Temiar Reduplication in One-Level Prosodic Morphology

Temiar reduplication is a difficult piece of prosodic morphology. This paper presents the first computational analysis of Temiar reduplication, using the novel finite-state approach of One-Level Prosodic Morphology originally developed by Walther (1999b, 2000). After reviewing both the data and the basic tenets of One-level Prosodic Morphology, the analysis is laid out in some detail, using the notation of the FSA Utilities finite-state toolkit (van Noord 1997). One important discovery is that in this approach one can easily define a regular expression operator which ambiguously scans a string in the left- or rightward direction for a certain prosodic property. This yields an elegant account of base-length-dependent triggering of reduplication as found in Temiar.

Finite-State Reduplication in One-Level Prosodic Morphology

Reduplication, a central instance of prosodic morphology, is particularly challenging for state-of-the-art computational morphology, since it involves copying of some part of a phonological string. In this paper I advocate a finite-state method that combines enriched lexical representations via intersection to implement the copying. The proposal includes a resource-conscious variant of automata and can benefit from the existence of lazy algorithms. Finally, the implementation of a complex case from Koasati is presented.

One-Level Prosodic Morphology

Recent developments in theoretical linguistics have lead to a widespread acceptance of constraint-based analyses of prosodic morphology phenomena such as truncation, infixation, floating morphemes and reduplication. Of these, reduplication is particularly challenging for state-of-the-art computational morphology, since it involves copying of some part of a phonological string. In this paper I argue for certain extensions to the one-level model of phonology and morphology (Bird & Ellison 1994) to cover the computational aspects of prosodic morphology using finite-state methods. In a nutshell, enriched lexical representations provide additional automaton arcs to repeat or skip sounds and also to allow insertion of additional material. A kind of resource consciousness is introduced to control this additional freedom, distinguishing between producer and consumer arcs. The non-finite-state copying aspect of reduplication is mapped to automata intersection, itself a non-finite-state operation. Bounded local optimization prunes certain automaton arcs that fail to contribute to linguistic optimisation criteria. The paper then presents implemented case studies of Ulwa construct state infixation, German hypocoristic truncation and Tagalog over-applying reduplication that illustrate the expressive power of this approach, before its merits and limitations are discussed and possible extensions are sketched. I conclude that the one-level approach to prosodic morphology presents an attractive way of extending finite-state techniques to difficult phenomena that hitherto resisted elegant computational analyses.

Computing Declarative Prosodic Morphology

This paper describes a computational, declarative approach to prosodic morphology that uses inviolable constraints to denote small finite candidate sets which are filtered by a restrictive incremental optimization mechanism. The new approach is illustrated with an implemented fragment of Modern Hebrew verbs couched in MicroCUF, an expressive constraint logic formalism. For generation and parsing of word forms, I propose a novel off-line technique to eliminate run-time optimization. It produces a finite-state oracle that efficiently restricts the constraint interpreter's search space. As a byproduct, unknown words can be analyzed without special mechanisms. Unlike pure finite-state transducer approaches, this hybrid setup allows for more expressivity in constraints to specify e.g. token identity for reduplication or arithmetic constraints for phonetics.

Processing Unknown Words in HPSG

The lexical acquisition system presented in this paper incrementally updates linguistic properties of unknown words inferred from their surrounding context by parsing sentences with an HPSG grammar for German. We employ a gradual, information-based concept of ``unknownness'' providing a uniform treatment for the range of completely known to maximally unknown lexical entries. ``Unknown'' information is viewed as revisable information, which is either generalizable or specializable. Updating takes place after parsing, which only requires a modified lexical lookup. Revisable pieces of information are identified by grammar-specified declarations which provide access paths into the parse feature structure. The updating mechanism revises the corresponding places in the lexical feature structures iff the context actually provides new information. For revising generalizable information, type union is required. A worked-out example demonstrates the inferential capacity of our implemented system.

OT SIMPLE - a construction-kit approach to Optimality Theory implementation

This paper details a simple approach to the implementation of Optimality Theory (OT, Prince and Smolensky 1993) on a computer, in part reusing standard system software. In a nutshell, OT's GENerating source is implemented as a BinProlog program interpreting a context-free specification of a GEN structural grammar according to a user-supplied input form. The resulting set of textually flattened candidate tree representations is passed to the CONstraint stage. Constraints are implemented by finite-state transducers specified as `sed' stream editor scripts that typically map ill-formed portions of the candidate to violation marks. EVALuation of candidates reduces to simple sorting: the violation-mark-annotated output leaving CON is fed into `sort', which orders candidates on the basis of the violation vector column of each line, thereby bringing the optimal candidate to the top. This approach gave rise to OT SIMPLE, the first freely available software tool for the OT framework to provide generic facilities for both GEN and CONstraint definition. Its practical applicability is demonstrated by modelling the OT analysis of apparent subtractive pluralization in Upper Hessian presented in Golston and Wiese (1996).

Coupling Phonology and Phonetics in a Constraint-Based Gestural Model

An implemented approach which couples a constraint-based phonology component with an articulatory speech synthesizer is proposed. Articulatory gestures ensure a tight connection between both components, as they comprise both physical-phonetic and phonological aspects. The phonological modelling of e.g. syllabification and phonological processes such as German final devoicing is expressed in the constraint logic programming language CUF. Extending CUF by arithmetic constraints allows the simultaneous description of both phonology and phonetics. Thus declarative lexicalist theories of grammar such as HPSG may be enriched up to the level of detailed phonetic realisation. Initial acoustic demonstrations show that our approach is in principle capable of synthesizing full utterances in a linguistically motivated fashion.