No fully-black-box reduction from ZKP to Argument systems

A reduction of class fully-black-box from ZKP to Argument systems would imply a contradiction.

Statement

Migrated verbatim from black-box-separations § Limitations:

• Non-black-box constructions exist. Barak’s non-black-box zero-knowledge construction uses the circuit of the adversary to achieve constant-round ZK arguments, bypassing oracle-separation impossibilities that apply to fully BB zero-knowledge protocols.

Notes

source: folklore: the claim carried no citation on the page it was migrated from, and none was invented.

Recorded during migration and not fixed — these are claims about the source text, not changes to it:

• NO CITATION. ‘Barak’s non-black-box zero-knowledge construction’ names an author and a result with no wikilink and no reference page. content/References/ has no Bar01/Barak entry. CLAUDE.md requires a citation for exactly this kind of claim, and it is not folklore.
• This is a barrier CIRCUMVENTION, not a barrier: it records that a known impossibility (GK96, constant-round black-box-simulation ZK) is bypassed by a non-black-box technique. The data model needs an explicit ‘circumvents barrier X’ edge type; there is nowhere to put this.
• The barrier it circumvents (GK96) is stated on a different page (content/Complexity/computational-zero-knowledge.md:35) with no cross-link in either direction.