It is well known that left conjuncts tend to be shorter in English coordinate structures. On the basis of Penn Treebank, Przepiórkowski and Woźniak 2023 (in ACL 2023 proceedings) show that this tendency depends on the difference between lengths of conjuncts: the larger the difference, the stronger the tendency for the shorter conjunct to occur on the left. However, this dynamics is observed only when the governor of the coordinate structure is on the left of the coordination (e.g., “Bring apples and oranges!”) or when it is absent (e.g., “Come and sing!”), and not when it is on the right (e.g., “Apples and oranges fell”). Given the principle of Dependency Length Minimization, this turns out to provide an argument for the symmetric structure of coordination. We replicate and sharpen this result on the basis of a much larger dataset: parts of the COCA corpus parsed with Stanza. We also investigate the dependence of this result on the assumed unit of length (word vs. character) and on genre.

The aim of this paper is to replicate and extend recent treebank-based considerations regarding the syntactic structure of coordination. Overall, we confirm the previous results that, given the principle of Dependency Length Minimization, corpus data suggest that the structure of coordination is symmetric. While previous work was based on 2 English datasets, we extend the investigation to 3 more English datasets, 3 Polish datasets, and UD corpora for a number of diverse languages. The results confirm the symmetric structure of coordination, but they also make it possible to question some of the previous findings regarding the exact symmetric structure of coordination.