Time Period

Synonyms

Time interval

Definition

If the time domain is a totally ordered set T = {t₁, t₂, t₃…} then a time period over T is defined as a convex subset of elements from T.

Example: If T = {d₁, d₂, d₃,…}, where d_i are consecutive dates, then [d₁₀, d₂₀] and [d₃₀, d₈₀] represent two time periods over T.

Key Points

In the area of temporal databases, a time period over T is usually defined as a distinct data type. Some researchers define a time period data type of the form [t_p, t_q]. Some others define such a data type of the form [t_p, t_q), i.e., its right end is closed.

Note that, initially, the term time interval was used instead of time period. This was later abandoned in order to avoid confusion, given that interval is a reserved word in SQL. Instead, time interval in today used with a different meaning (see time interval).

Cross-References

• Absolute Time

• Chronon

• Period-Stamped Temporal Models

• Time Domain

• Time Interval

• Temporal Granularity