Definition · foundations
idempotency
idempotency is a property that lets the same action run again without causing a second change. You can spot idempotency in practice when the record shows what the system observes, what choice it makes, and what changes next, without asking the reader to guess or trust a slogan.
157 definitions656 sourced recordsNamed source: ACL Anthology
Why does idempotency matter?
A safe retry should not repeat the effect. This matters when a timeout hides whether the first call worked. For idempotency, start with three checks: What can the system observe? What choice can it make? What changes after it acts? The answers should point to visible evidence, not a promise.
What does idempotency look like?
A payment request uses one key, so a retry cannot charge the card twice. This example makes idempotency visible by naming the actor, the action, and the result in practice. It is an illustration for readers, not a claim that every product behaves this way.
What is idempotency easy to confuse with?
Idempotency makes repeats have one effect. Deduplication finds and removes copies after they appear. The closest entries here are human on the loop, indirect prompt injection, world model. Compare their definitions with idempotency before using the names as if they mean the same thing. That comparison keeps idempotency separate from nearby ideas without pretending the boundary is always perfect.
How certain is this definition?
This definition is provisional. ACL Anthology supports the version you see today, but a better or more direct source may change it. Open the cited page and check its date before you use this entry to choose a product, write a policy, set a safety control, or design a system.
Who introduced the term idempotency?
We have not verified who first introduced idempotency. The source supports a useful definition, but it may not be the earliest use. Until a dated primary record settles the question, we leave the origin open. A popular article or product page is not enough to name the person who coined a term.
What should you understand before idempotency?
Read artificial intelligence (AI) first when idempotency depends on a more basic idea or mechanism. The link gives you a useful route through the glossary. It does not mean every author teaches the subject in this order, so follow the source when the sequence matters.
What should this term help you answer?
Use idempotency to ask what an agent can observe, decide, change, remember, or hand off. The questions below turn the definition into a practical check. They are prompts for your own work, not claims made by the source, so change them to fit the system you are examining.
- What can the system observe?
- What choice can it make?
- What changes after it acts?
Which source supports this definition of idempotency?
ACL Anthology supports this working definition of idempotency. We checked the link on 2026-07-12. Open the original record for its context, methods, limits, and publication details. The short explanation here is a guide to idempotency; the linked source remains the evidence to inspect when the wording or boundary matters.
source foundidempotencyChecked 2026-07-12→