Solving the Federal Finality–Appealability Problem

We present an empirical evaluation of three methods for the treatment of non-projective structures in transition-based dependency parsing: pseudo-projective parsing, non-adjacent arc transitions, and online reordering. We compare both the theoretical coverage and the empirical performance of these methods using data from Czech, English and German. The results show that although online reordering is the only method with complete theoretical coverage, all three techniques exhibit high precision but somewhat lower recall on non-projective dependencies and can all improve overall parsing accuracy provided that non-projective dependencies are frequent enough. We also find that the use of non-adjacent arc transitions may lead to a drop in accuracy on projective dependencies in the presence of long-distance non-projective dependencies, an effect that is not found for the two other techniques

The Tree-Generative Capacity of Combinatory Categorial Grammars

The generative capacity of combinatory categorial grammars as acceptors of tree languages is investigated. It is demonstrated that the such obtained tree languages can also be generated by simple monadic context-free tree grammars. However, the subclass of pure combinatory categorial grammars cannot even accept all regular tree languages. Additionally, the tree languages accepted by combinatory categorial grammars with limited rule degrees are characterized: If only application rules are allowed, then they can accept only a proper subset of the regular tree languages, whereas they can accept exactly the regular tree languages once first degree composition rules are permitted

Dependency structures and lexicalized grammars

In this dissertation, we show that that both the generative capacity and the parsing complexity of lexicalized grammar formalisms are systematically related to structural properties of the dependency structures that these formalisms can induce. Dependency structures model the syntactic dependencies among the words of a sentence. We identify three empirically relevant classes of dependency structures, and show how they can be characterized both in terms of restrictions on the relation between dependency and word-order and within an algebraic framework. In the second part of the dissertation, we develop natural notions of automata and grammars for dependency structures, show how these yield infinite hierarchies of ever more powerful dependency languages, and classify several grammar formalisms with respect to the languages in these hierarchies that they are able to characterize. Our results provide fundamental insights into the relation between dependency structures and lexicalized grammars.In dieser Arbeit zeigen wir, dass sowohl die Ausdrucksmächtigkeit als auch die Verarbeitungskomplexität von lexikalisierten Grammatikformalismen auf systematische Art und Weise von strukturellen Eigenschaften der Dependenzstrukturen abhängen, die diese Formalismen induzieren. Dependenzstrukturen modellieren die syntaktischen Abhängigkeiten zwischen den Wörtern eines Satzes. Wir identifizieren drei empirisch relevante Klassen von Dependenzstrukturen und zeigen, wie sich diese sowohl durch Einschränkungen der Interaktion zwischen Dependenz und Wortstellung, als auch in einem algebraischen Rahmen charakterisieren lassen. Im zweiten Teil der Arbeit entwickeln wir natürliche Begriffe von Automaten und Grammatiken für Dependenzstrukturen, zeigen, wie diese zu unendlichen Hierarchien immer ausdrucksmächtigerer Dependenzsprachen führen, und klassifizieren mehrere Grammatikformalismen in Bezug auf die Sprachen in diesen Hierarchien, die von ihnen charakterisiert werden können. Unsere Resultate liefern grundlegende Einsichten in das Verhältnis zwischen Dependenzstrukturen und lexikalisierten Grammatiken

Towards a constraint parser for categorial type logics

This thesis shows how constraint programming can be applied to the processing of Categorial Type Logics(CTL). It presents a novel formalisation of the parsing task for categorial grammars as a tree configuration problem, and demonstrates how a recent proposal for emph{structural constraints} on CTL parse trees can be integrated into this framework. The resulting processing model has been implemented using the Mozart programming environment. It appears to be a promising starting point for further research on the application of constraint parsing to CTL and the investigation of the practical processing complexity of CTL grammar fragments.}

Towards a constraint parser for categorial type logics

This thesis shows how constraint programming can be applied to the processing of Categorial Type Logics(CTL). It presents a novel formalisation of the parsing task for categorial grammars as a tree configuration problem, and demonstrates how a recent proposal for emph{structural constraints} on CTL parse trees can be integrated into this framework. The resulting processing model has been implemented using the Mozart programming environment. It appears to be a promising starting point for further research on the application of constraint parsing to CTL and the investigation of the practical processing complexity of CTL grammar fragments.}