Abstract TAGs were recently shown not to be closed under strong lexicalization but to be strongly lexicalizable by context-free tree grammars of rank 2. This paper presents an alternative lexicalization procedure that builds on an earlier generalization of TAGs to multi-dimensional trees. A previous theorem that every Tree Substitution grammar is strongly lexicalized by a corresponding TAG is lifted to higher dimensions to show that for every d-dimensional TAG there exists a (d+1)-dimensional TAG that strongly lexicalizes it. A similar lifting reveals that d-dimensional TAGs are not closed under strong lexicalization, so for arbitrary TAGs an increase in dimensionality is an unavoidable consequence of strong lexicalization.
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@InProceedings{DeSantoEtAl16TAG,
author = {De Santo, Aniello and Aks\"{e}nova, Al\"{e}na and Graf, Thomas},
title = {An Alternate View on Strong Lexicalization in {TAG}},
booktitle = {Proceedings of the 12th International Workshop on {T}ree {A}djoining {G}rammars and Related Formalisms ({TAG}+12)},
year = {2016},
address = {Düsseldorf, Germany},
pages = {93--102},
url = {http://www.aclweb.org/anthology/W16-3310}
}