Definition
Plain language
A rule that only one part of a system can use a shared resource at a time.
As stated in the literature
A concurrency safety property guaranteeing at most one process holds a given lock or shared resource simultaneously; one of the four properties enforced in verified agent coordination protocols.
Why it matters: It prevents the chaos of multiple processes touching the same resource at once, a core requirement for safe coordination.
For example, it ensures only one agent can edit a shared file at a time, so two of them don't overwrite each other's changes.
Heard on the show
“The four properties TraceFix checks — mutual exclusion, deadlock freedom, orphan locks, channel drainage — map directly onto MAST's specification-and-orchestration categories.”Episode 034 — Catching Multi-Agent Deadlocks Before Deployment With a 40-Year-Old Tool