A stronger null hypothesis for crossing dependencies

Abstract

The syntactic structure of a sentence can be modeled as a tree where vertices are words and edges indicate syntactic dependencies between words. It is well-known that those edges normally do not cross when drawn over the sentence. Here a new null hypothesis for the number of edge crossings of a sentence is presented. That null hypothesis takes into account the length of the pair of edges that may cross and predicts the relative number of crossings in random trees with a small error, suggesting that a ban of crossings or a principle of minimization of crossings are not needed in general to explain the origins of non-crossing dependencies. Our work paves the way for more powerful null hypotheses to investigate the origins of non-crossing dependencies in nature.

typos corrected and English improved

References in corpus (1)

• Random $k$-noncrossing RNA Structures

Cited by in corpus (11)

• Text authorship identified using the dynamics of word co-occurrence networks
• Are crossing dependencies really scarce?
• The scarcity of crossing dependencies: a direct outcome of a specific constraint?
• Memory limitations are hidden in grammar
• Crossings as a side effect of dependency lengths
• The sum of edge lengths in random linear arrangements
• Random crossings in dependency trees
• Towards a theory of word order. Comment on "Dependency distance: a new perspective on syntactic patterns in natural language" by Haitao Liu et al
• Compression and the origins of Zipf's law of abbreviation
• Edge crossings in random linear arrangements
• A commentary on "The now-or-never bottleneck: a fundamental constraint on language", by Christiansen and Chater (2016)