ZKProof 5.5 in Barcelona was a blast! We focused on standardization, and all the 100 participants, well, participated! 
Here’s summary of the talks, for those who couldn’t make it, but also as reference for the workgroups we formed.
Ying Tong Lai delivered an illuminating presentation (slides are here) that advanced understanding of recursive proof composition, clearly explaining techniques like folding schemes, highlighting implementations in areas like neural networks, outlining insightful criteria for comparison, and recruiting participants to drive progress on open problems around specifications, benchmarks, tooling, and theory through collaborative initiatives like ZK Proof.
Overview:
- Ying Tong gave an overview of recursive proof composition, covering motivations like reducing proof size and enabling incrementally verifiable computation.
- She explained core techniques like full recursion, accumulation schemes, and folding schemes.
- Ying highlighted real-world implementations applying these techniques to use cases like verifiable delay functions and virtual machines.
Details:
- She covered how full recursion represents the verifier circuit inside proofs, requiring a succinct verifier.
- Ying explained how accumulation and folding schemes reduce overhead by only verifying parts of the computation.
- She outlined criteria for comparing systems like zero knowledge, field size, threshold, and efficiency.
- Ying detailed the security bug found in the Nova implementation.
Discussion:
- Proposed working groups on topics like tooling, benchmarking, specifications, and theoretical foundations.
- Emphasized need to improve specifications and standards around things like curve cycles.
- Discussed tradeoffs between small field FRI and folding schemes.
Key Takeaways:
- Recent advances have reduced overhead of recursive proofs, enabling large computations.
- A variety of real-world implementations are applying these techniques.
- Open problems remain around specifications, benchmarks, tooling, and theory.
- Collaborative initiatives like ZK Proof standards can help drive progress.