wMSO theories as grammar formalisms
Theoretical Computer Science - Algebraic methods in language processing
Introduction to Automata Theory, Languages, and Computation (3rd Edition)
Introduction to Automata Theory, Languages, and Computation (3rd Edition)
A Learning Algorithm for Multi-dimensional Trees, or: Learning Beyond Context-Freeness
ICGI '08 Proceedings of the 9th international colloquium on Grammatical Inference: Algorithms and Applications
Proceedings of the 2009 conference on Finite-State Methods and Natural Language Processing: Post-proceedings of the 7th International Workshop FSMNLP 2008
Journal of Computer and System Sciences
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We present and compare two methods of how to make derivation in a Tree Adjoining Grammar a regular process (in the Chomsky hierarchy sense) without loss of expressive power. One regularization method is based on an algebraic operation called Lifting, while the other exploits an additional spatial dimension by transforming the components of a TAG into three-dimensional trees. The regularized grammars generate two kinds of "encoded" trees, from which the intended ones can be reconstructed by a simple decoding function. We can show the equivalence of these two two-step approaches by giving a direct translation between lifted and three-dimensional trees and proving that via this translation it is possible to switch between the encodings without losing the information necessary for the reconstruction of the intended trees.