Knowledge Systems Laboratory, Stanford
University
3
Points and Intervals
uTime point
„Position on a
temporal coordinate system
E.g., “2:22 p.m.,
February 2, 2000”
„Primitive
object
„Analogous to a
real number
„Also
represented at varying granularities
E.g., “March 14,
1994”
uTime interval
„Set of two or
more time points
E.g., “the 16th century”
“10:50 to 11:00 a.m. on
May 30, 1993”
“noon to 1:00 p.m. every
Tuesday in 2000”
„Primitive
object
„Convex interval analogous to interval on number line
„Has two
distinguished points: Start-Point and End-Point
„Can be
Left-Open, Left-Closed, Right-Open, and/or Right-Closed