What's that CS "big word" term for the same action always having the same effect

Question

There's a computer science term for this that escapes my head, one of those words that ends with "-icity".

It means something like a given action will always produce the same result, IE there won't be any hysteresis, or the action will not alter the functioning of the system...

Ring a bell, anyone? Thanks.

_{Apologies for the tagging, I'm only tagging it Java b/c I learned about this in a Java class back in school and I figure that crowd tends to have more CS background...}

Answer 1

deterministic ,.,-=

Answer 2

You mean an atomic block of code?

Answer 3

you mean idempotent ??

Answer 4

Nullipotent?

Answer 5

or the action will not alter the functioning of the system...

Are you looking for ‘idempotence’?

Answer 6

you mean idempotence?

Answer 7

In math, a function 'f' is idempotent if multiple applications do not change the result.

Answer 8

This could mean two different things:

deterministic - meaning that given the same initial state, the same operation (with exactly the same data) will always produce the same resulting state (and optional output.) - http://en.wikipedia.org/wiki/Determinism

i.e. same action has the same effect - assuming you start from the same place in the same system. (Nothing random about it, nothing fed in from the outside that could effect the result...)

idempotent - meaning that a command run once produces some effect, but running the command multiple times has that effect only once - as though it had only been run once. - http://en.wikipedia.org/wiki/Idempotence

i.e. same action has the same effect - same effect if you run it once, or multiple times one after another times

Answer 9

Referential transparency is also used in some CS circles.

Answer 10

The A in ACID.

Atomicity - states that database modifications must follow an “all or nothing” rule. Each transaction is said to be “atomic.” If one part of the transaction fails, the entire transaction fails.

Answer 11

It sounds like what you're describing would be a memoryless function. Although the term memorylessness is usually used for stochastic distributions, I don't quite remember if it has a programming equivalent...

Answer 12

side effect-free?

Answer 13

Are you looking for invariant?

http://en.wikipedia.org/wiki/Invariant_%28computer_science%29

In computer science, a predicate is called an invariant to a sequence of operations if the predicate always evaluates at the end of the sequence to the same value as before starting the sequence.

Answer 14

The "ends with -icity" part of your question makes me think you might be looking for monotonicity, even though it does not quite match description/definition of the word. From the Wikipedia article:

In mathematics, a monotonic function (or monotone function) is a function which preserves the given order. This concept first arose in calculus, and was later generalized to the more abstract setting of order theory.

In the following illustrations (also borrowed from the Wikipedia article) three functions are drawn:

A:      B:      C:

A and B and both monotonic (increasing and decreasing respectively), while C is not monotonic.