# Content Differences in Syntactic and Semantic Representations

## TL;DR

This paper compares syntactic and semantic representations using Universal Dependencies and UCCA, revealing key content divergences and implications for semantic parsing in text understanding.

## Contribution

It provides an empirical comparison of UD and UCCA, identifying main content differences and proposing a methodology for fine-grained evaluation of semantic parsing.

## Key findings

- Most content divergences are due to distinctions like Scene vs. non-Scene in UCCA.
- Different treatments of multi-word expressions and inter-clause linkage cause significant differences.
- The comparison methodology aids in evaluating and improving UCCA parsing.

## Abstract

Syntactic analysis plays an important role in semantic parsing, but the nature of this role remains a topic of ongoing debate. The debate has been constrained by the scarcity of empirical comparative studies between syntactic and semantic schemes, which hinders the development of parsing methods informed by the details of target schemes and constructions. We target this gap, and take Universal Dependencies (UD) and UCCA as a test case. After abstracting away from differences of convention or formalism, we find that most content divergences can be ascribed to: (1) UCCA's distinction between a Scene and a non-Scene; (2) UCCA's distinction between primary relations, secondary ones and participants; (3) different treatment of multi-word expressions, and (4) different treatment of inter-clause linkage. We further discuss the long tail of cases where the two schemes take markedly different approaches. Finally, we show that the proposed comparison methodology can be used for fine-grained evaluation of UCCA parsing, highlighting both challenges and potential sources for improvement. The substantial differences between the schemes suggest that semantic parsers are likely to benefit downstream text understanding applications beyond their syntactic counterparts.