diff --git a/backlog/infrastructure/2025-08-15_parameter-tying-framework.md b/backlog/infrastructure/2025-08-15_parameter-tying-framework.md new file mode 100644 index 00000000..0afc189e --- /dev/null +++ b/backlog/infrastructure/2025-08-15_parameter-tying-framework.md @@ -0,0 +1,76 @@ +--- +id: "parameter-tying-framework" +title: "Design parameter tying framework for GPy multioutput kernels" +status: "Ready" +priority: "High" +created: "2025-08-15" +last_updated: "2025-08-15" +owner: "Neil Lawrence" +github_issue: "" +dependencies: "" +tags: +- parameter-tying +- multioutput +- kernel-framework +- architecture +--- + +# Investigate parameter tying limitations and create CIP for discussion + +## Description + +During LFM kernel code review, we identified that GPy lacks systematic parameter tying capabilities compared to GPmat's `modelTieParam()` functionality. This limitation affects combination kernels such as multiouptut or additive kernels. We need to investigate the scope of this problem and create a CIP to discuss potential solutions with the community. + +## Problem Statement + +- **Current Limitation**: GPy's parameter system doesn't support tying parameters across different kernel components +- **Impact on LFM**: Forces complex parameter handling in EQ_ODE1 and EQ_ODE2 kernels +- **Broader Impact**: May affect other multiple kernel scenarios where parameters should be shared +- **Comparison**: GPmat has `modelTieParam()` functionality that GPy lacks + +## Investigation Needed + +### 1. Scope Assessment +- [ ] Search existing GitHub issues for parameter tying discussions +- [ ] Identify other kernels/models that could benefit from parameter tying +- [ ] Assess impact on current GPy codebase + + +### 2. Community Input +- [ ] Create GitHub issue and associated CIP to discuss parameter tying needs +- [ ] Gather feedback from GPy maintainers and users +- [ ] Identify use cases beyond LFM kernels +- [ ] Assess priority relative to other GPy improvements + +### 3. Technical Analysis +- [ ] Analyze GPmat's parameter tying implementation +- [ ] Review GPy's current parameter system architecture +- [ ] Identify potential integration points +- [ ] Assess complexity and maintenance burden + +## Acceptance Criteria + +- [ ] Complete investigation of existing GitHub issues and discussions +- [ ] Document scope of parameter tying needs across GPy +- [ ] Create CIP for parameter tying framework discussion +- [ ] Gather community feedback on approach and priority +- [ ] Provide recommendations for next steps + +## Implementation Notes + +- Focus on problem identification and community discussion +- Avoid prescribing specific solutions until community input is gathered +- Consider whether this should be a separate CIP or part of broader multioutput improvements +- Document trade-offs between different approaches + +## Related + +- CIP: 0001 (LFM kernel implementation) - may depend on parameter tying +- GPy parameter system design +- GPmat parameter tying implementation +- Multioutput kernel architecture discussions + +## Progress Updates + +### 2025-08-15 +Task created after identifying parameter tying as a potential limitation during LFM kernel code review. Need to investigate scope and create CIP for community discussion.