Definition
Plain language
A guarantee that a system will eventually make progress, rather than just never doing anything wrong by sitting still.
As stated in the literature
A class of formal properties asserting that something good eventually happens (progress, termination); distinguished from safety properties and explicitly not checked in TraceFix's verification of agent coordination.
Why it matters: It's the difference between a system that makes progress and one that's technically safe but frozen, and notably some verification efforts check safety without it.
For example, a liveness guarantee promises that every request a system receives will eventually get answered, not just that it never gives a wrong answer.
Heard on the show
“Third — liveness isn't checked.”Episode 034 — Catching Multi-Agent Deadlocks Before Deployment With a 40-Year-Old Tool