SUTIME: A Library for Recognizing and Normalizing Time Expressions
Detecting Temporal Expressions
There are 2 steps for extracting time from natural language expressions 
 Detecting temporal expressions.
 Extracting normalized time expressions from natural language phrases.
This paper is about the latter. They use TIMEX representation of time expression.
Types of Temporal Expressions
There are 4 types of temporal expressions 

Time  A time point indicating a particular instance on a time scale. Examples include Nov 20 1988, 5:30 PM, now, next weekend or Sunday Evening.

Duration  The amount of intervening time between the two endpoints of a time interval. Examples include 5 days, 10 months, a decade, few years or 23 months.

Interval  A range of time defined by a start and end time points. Examples include Jan 2021 to Feb 2022.

Set  A set of temporals. Examples include “every 3rd Sunday”.
Datasets and Evaluation
 A popular dataset is TempEval2. SUTime had the best Recall and F1 on this dataset but HeidelTime had the best precision. They’ve incorporated the work into Stanford CoreNLP.
Kaushik Rangadurai
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