# PART 2: Existing subsystems to reuse instead of building be… (1)

Checks 1 to 4 of 4, each with its evidence

## What you can do here

- **Verify 1: Open Policy Agent (OPA) | General policy en…**: Verify: Open Policy Agent (OPA) | General policy engine using the Rego langua…
- **Verify 2: Cedar | Authorisation policy language desig…**: Verify: Cedar | Authorisation policy language designed for automated reasonin…
- **Verify 3: OpenFGA | Relationship-based (Zanzibar-styl…**: Verify: OpenFGA | Relationship-based (Zanzibar-style) fine-grained authorisat…
- **Verify 4: Suggested pattern (assessment): OpenFGA ans…**: Verify: Suggested pattern (assessment): OpenFGA answers who is related to who…
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- **Open Meet the research: 2.7 Policy and author**