# Liveness Witness

> A facility that answers whether a process is still running by checking that the process is present, so its absence proves death while its presence proves nothing.

Record: `lexicon:liveness-witness`
Kind: mechanism
Layer: [Execution Core](https://banes-lab.com/records/layer/execution-core.md)
Canonical: https://banes-lab.com/ontology/lexicon#lexicon-liveness-witness

Listed in [Lexicon terms](https://banes-lab.com/api/records/lexicon.md), after [Joiner](https://banes-lab.com/records/lexicon/joiner.md) and before [Distinguished Copy](https://banes-lab.com/records/lexicon/distinguished-copy.md).

## Category

- [Coordination Surfaces](https://banes-lab.com/records/lexicon-category/coordination-surfaces.md)

## Required by

- [One-Sided Liveness](https://banes-lab.com/records/architecture/one-sided-liveness.md)

## Linked from

- [Coordination Surfaces](https://banes-lab.com/ontology/principles/architecture-category-coordination-surfaces.md)

## Evidence in the code

- [models/invocation.model.md](https://banes-lab.com/source/coordination/models/invocation.model.md.md)