1. The investigation of mathematical properties of data, such as numbers, and of operations on data, such as the addition and multiplication of numbers.
2. A collection of sets together with a collection of operations over those sets. Many examples involve only one set, such as the following:
In computer science, however, it is natural to consider algebras involving more than one set. These are called
many-sorted algebras, in contrast to
single-sorted algebras with only one set. For example, in programming languages there are different data types such as Boolean, integer, real, character, etc., as well as user-defined types. Operations on elements of these types can then be seen as giving rise to a many-sorted algebra. By stating axioms that define properties of these operations, an abstract data type can be specified.
See also algebraic structure,
signature.