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Temporal information detection

Introduction

The temporal-information detector identifies and returns—in normalized format—the following time expressions:

Expression type Description Examples
Time point A specific time The Declaration was signed on July 4, 1776.

The plane should take off at 3PM.

In November 1996 I traveled to the United States.

A big change took place in 2016.
Time span An amount of time units, from minutes up to years It took her three minutes to find the solution.

Your condition will continue to improve over the next two weeks.

I have known her for more than ten years.
Time interval A time interval (from ... to ...) He ruled the region from July 2005 to September 2011.

Value normalization

Time point

Time point expressions are normalized according to the ISO 8601 standard. Here are some examples of value normalization:

  • July 4, 17761776-07-04
  • 3PM-----T15
  • November 19961996-11
  • 20162016

Time span

Time span expressions are normalized using this format:

[ sign ] quantity unit-of-measure

For example:

Seven days7 day

Possible units of measure are:

  • year
  • month
  • day
  • hour
  • minute

Quantity can be indefinite, for example:

For some months I've been skeptical, but now I believe it.indefinite month

Weeks are returned as days, centuries as years, etc. For example:

Two weeks14 day

The optional sign can be + (plus sign) or - (minus sign) and denotes time spans that "add" or "subtract" time from an explicit or implicit time point. For example:

  • The first agreement was in 2009. After eight years the companies merged.+ 8 year, meaning eight years after 2009
  • These events took place 30 years ago.- 30 year, meaning thirty years before a time that was "this year"—but not further specified—for the writer or speaker.

Time interval

Time interval expression are normalized using this format:

"from" time point / "to" time point

Left and right time points are normalized according to the ISO 8601 standard. For example:

from July 2005 to September 20112005-07/2011-09

Derived time points

The detector is also capable of deriving time points from deixes referring to other time points.

In particular, the detector can derive a time point from:

  • "Before/after" expressions that are recognized as time spans and referred to a time point

    For example, in:

    I first traveled to Australia in 2002 and returned fifteen years later,

    the expression fifteen years later is not recognizable as a time point by itself, but is recognized as a time span (normalized to + 15 year) and, once referred to 2002—which is recognized as a time point—, makes the detector derive a new time point by adding the time span. In this case the new time point is 2017, which is 2002 + 15.

  • "Equal to" expressions referred to a time point

    For example, in:

    We met on July 27, 2014. On the same day we became business partners.

    the expression On the same day is not recognizable as a time point by itself, but once referred to July 27, 2014—which is recognized as a time point—and interpreted as "the same", makes the detector derive another occurrence of the explicit time point, in this case 2014-07-27.

Derived time points are flagged as such in the detectors' output.

Useful resources