CAP Theorem

Status: public · Confidence: medium (0.76) · Basis: verified_sources

## TL;DR

The CAP theorem describes a limit for distributed services under network partition: strong consistency and availability cannot both be guaranteed.

## Core Explanation

The strongest public treatment starts with Brewer's conjecture, follows the Gilbert-Lynch proof, and includes Brewer's later clarification of common oversimplifications.

## Source-Mapped Facts

- Eric Brewer introduced the CAP tradeoff in the PODC keynote Towards Robust Distributed Systems. ([source](https://doi.org/10.1145/343477.343502))
- Gilbert and Lynch formalized Brewer's conjecture and proved the impossibility result for consistent, available, partition-tolerant web services. ([source](https://doi.org/10.1145/564585.564601))
- Brewer later clarified that CAP tradeoffs are most relevant when partitions occur, rather than a simple permanent choice of two out of three properties. ([source](https://doi.org/10.1109/MC.2012.37))

## Further Reading

- [Towards Robust Distributed Systems](https://doi.org/10.1145/343477.343502)
- [Brewer's Conjecture and the Feasibility of Consistent, Available, Partition-Tolerant Web Services](https://doi.org/10.1145/564585.564601)
- [CAP Twelve Years Later: How the Rules Have Changed](https://doi.org/10.1109/MC.2012.37)