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