The scarcity of crossing dependencies: a direct outcome of a specific constraint?

Abstract

The structure of a sentence can be represented as a network where vertices are words and edges indicate syntactic dependencies. Interestingly, crossing syntactic dependencies have been observed to be infrequent in human languages. This leads to the question of whether the scarcity of crossings in languages arises from an independent and specific constraint on crossings. We provide statistical evidence suggesting that this is not the case, as the proportion of dependency crossings of sentences from a wide range of languages can be accurately estimated by a simple predictor based on a null hypothesis on the local probability that two dependencies cross given their lengths. The relative error of this predictor never exceeds 5% on average, whereas the error of a baseline predictor assuming a random ordering of the words of a sentence is at least 6 times greater. Our results suggest that the low frequency of crossings in natural languages is neither originated by hidden knowledge of language nor by the undesirability of crossings per se, but as a mere side effect of the principle of dependency length minimization.

minor corrections; in press in Physical Review E

References in corpus (7)

• The spatial structure of networks
• Optimal design of spatial distribution networks
• On the origin of long-range correlations in texts
• Are crossing dependencies really scarce?
• A stronger null hypothesis for crossing dependencies
• Non-crossing dependencies: least effort, not grammar
• Crossings as a side effect of dependency lengths

Cited by in corpus (14)

• Are crossing dependencies really scarce?
• Anti dependency distance minimization in short sequences. A graph theoretic approach
• Memory limitations are hidden in grammar
• Crossings as a side effect of dependency lengths
• The sum of edge lengths in random linear arrangements
• On the relation between dependency distance, crossing dependencies, and parsing. Comment on "Dependency distance: a new perspective on syntactic patterns in natural languages" by Haitao Liu et al
• Edge crossings in random linear arrangements
• The optimal placement of the head in the noun phrase. The case of demonstrative, numeral, adjective and noun
• Swap distance minimization in SOV languages. Cognitive and mathematical foundations
• The expected sum of edge lengths in planar linearizations of trees. Theory and applications
• Dependency distance minimization predicts compression
• Liberating language research from dogmas of the 20th century
• Inherent Dependency Displacement Bias of Transition-Based Algorithms
• The Impact of Edge Displacement Vaserstein Distance on UD Parsing Performance