The system is knowledge sound even if the outer proof system only provides standard (and not knowledge) soundness

We don't know how to prove knowledge soundness of systems with linear recursion depth in general

Recursion based on succinct verification only makes sense when the verification circuit of inner proof system is simpler than the circuit proved by the inner proof system

Using cycle of curves, we can do recursion without any field emulation

The folding scheme discussed in the lecture is zero-knowledge

The verifier complexity of IVC from folding schemes is O(t * |x| + |F|), where t is the current time step, |x| is the size of public input at each step, and |F| is the size of the transition function.

In IVC from folding schemes, the prover proves an augmented circuit that also proves that the folding was done correctly

The extractor runtime in IVC from folding schemes grows exponentially with recursion depth