Formal Definitions

next up previous
Next: Safety of Expressions Up: The Tuple Relational Previous: Example Queries

Formal Definitions

  1. A tuple relational calculus expression is of the form

    where is a formula.

    Several tuple variables may appear in a formula.

  2. A tuple variable is said to be a free variable unless it is quantified by a or a . Then it is said to be a bound variable.

  3. A formula is built of atoms. An atom is one of the following forms:
  4. Formulae are built up from atoms using the following rules:
  5. Note some equivalences:

Page created and maintained by Osmar R. Zaï ane
Last Update: Wed Sep 20 15:45:57 PDT 1995