Temporal expression normalisation in natural language texts

TL;DR

This paper presents a new rule-based system for normalizing temporal expressions in English texts, outperforming existing methods and providing a new annotated corpus for research.

Contribution

A novel rule-based architecture for temporal expression normalization, along with a new annotated corpus, advancing the state-of-the-art in temporal information extraction.

Findings

Outperforms TempEval-2 shared task systems

Achieves better results than previous systems

Provides a publicly available annotated corpus

Abstract

Automatic annotation of temporal expressions is a research challenge of great interest in the field of information extraction. In this report, I describe a novel rule-based architecture, built on top of a pre-existing system, which is able to normalise temporal expressions detected in English texts. Gold standard temporally-annotated resources are limited in size and this makes research difficult. The proposed system outperforms the state-of-the-art systems with respect to TempEval-2 Shared Task (value attribute) and achieves substantially better results with respect to the pre-existing system on top of which it has been developed. I will also introduce a new free corpus consisting of 2822 unique annotated temporal expressions. Both the corpus and the system are freely available on-line.