PPT Slide
Single or Interval Values
Add more on single or interval values.
- REAL-, INTEGER- and COUNT-typed attributes may be either a single value or an interval (value-pair).
- There are eight types of intervals:
- Four bounded interval types:
- (a, b), [a, b), (a, b], and [a, b]
- Four unbounded interval types:
- (a, +infinity), [a, +infinity), (-infinity, b), and (-infinity, b]
- Notation interpretation example: (5, +infinity)
- The span of numbers included in the group is often imagined as being on a number line, usually the x-axis.
- The '(5' on the left means the set of numbers starts at the real number which is immediately to the right of 5 on the number line. It means you should imagine a number the tinniest bit greater than 5, and that is where the group of numbers begins. The parenthesis to the left of 5 is called a round bracket or an exclusive bracket. That is, 5 is excluded from the group, but the numbers directly to the right of 5 are included. Simply put, numbers greater than 5 are included.
- The group of numbers continues to include values greater than 5 all the way to a value which is infinitely greater than 5. That is, the set of numbers goes all the way to positive infinity.
- Infinity symbols are always accompanied by round brackets.