2. proof system modifications

the original zcash/halo2 consists of:

• an optimising system compatible with UltraPlonK arithmetisation;
• the UltraPlonK interactive oracle proof; and
• the inner product argument, used as a polynomial commitment scheme.

popular forks of halo2 have incorporated proof system modifications across the stack.

arithmetisation

• Axiom’s halo2-base, a frontend to halo2’s cell assignment API

interactive oracle proof (IOP)

• privacy-scaling-exploration’s Challenge API, which introduces multiple phases to the IOP
• privacy-scaling-exploration’s shuffle API, which introduces a multiset equality check to the IOP

lookups

• mvlookup: implementation of log-derivative based MVLookup
• cq: implementation of cached quotients lookup cq

commitment scheme

• privacy-scaling-exploration’s integration of the KZG polynomial commitment scheme

general experimentation

• han0110/plonkish: implementations of HyperPlonK, Sangria, ProtoStar, and more