Number properties - Commutative, associative

Commutative - order - 4+5 = 5+4
Associative - grouping - (4 + 5) + 6 = 5 + (4 + 6)
http://www.onlinemathlearning.com/number-properties.html

http://en.wikipedia.org/wiki/Idempotence
In computer science, the term idempotent is used to describe methods or subroutine calls that can safely be called multiple times, as invoking the procedure a single time or multiple times has the same result; i.e., after any number of method calls all variables have the same value as they did after the first call.
eg. table lookups

http://en.wikipedia.org/wiki/Atomicity_(database_systems)
atomic transaction, a series of database operations either all occur, or nothing occurs.

http://en.wikipedia.org/wiki/Deterministic_system_(mathematics)
In mathematics, a deterministic system is a system in which no randomness is involved in the development of future states of the system