# Are crossing dependencies really scarce?

arXiv: https://arxiv.org/abs/1703.08324 · HTML: https://mlsanity.com/paper/1703.08324/

## Key facts

- Cited by 7 papers in the map (data through 14 Oct 2026).
- First posted on arXiv 24 Mar 2017.

## Built on by (most cited first, 7 of 7)

- [A Cross-Linguistic Pressure for Uniform Information Density in Word Order](https://mlsanity.com/paper/2306.03734/) (2023)
- [The Linear Arrangement Library. A new tool for research on syntactic dependency structures](https://mlsanity.com/paper/2112.02512/) (2021)
- [The expected sum of edge lengths in planar linearizations of trees. Theory and applications](https://mlsanity.com/paper/2207.05564/) (2022)
- [Better Benchmarking LLMs for Zero-Shot Dependency Parsing](https://mlsanity.com/paper/2502.20866/) (2025)
- [Who is the root in a syntactic dependency structure?](https://mlsanity.com/paper/2501.15188/) (2025)
- [The Impact of Edge Displacement Vaserstein Distance on UD Parsing Performance](https://mlsanity.com/paper/2209.07139/) (2022)
- [Formal Constraints on Dependency Syntax](https://mlsanity.com/paper/2604.04542/) (2026)

## Abstract (arXiv)

The syntactic structure of a sentence can be modelled as a tree, where vertices correspond to words and edges indicate syntactic dependencies. It has been claimed recurrently that the number of edge crossings in real sentences is small. However, a baseline or null hypothesis has been lacking. Here we quantify the amount of crossings of real sentences and compare it to the predictions of a series of baselines. We conclude that crossings are really scarce in real sentences. Their scarcity is unexpected by the hubiness of the trees. Indeed, real sentences are close to linear trees, where the potential number of crossings is maximized.