{"data":{"event":{"id":"4c914784-5f72-49d1-95d3-94c0a60ce131","slug":"claude-hadamard-matrix-668","title":"A three-human plus Claude team is reported to construct a Hadamard matrix of order 668","short_summary":"In August 2026 Epoch’s open-problems index listed a Hadamard matrix of order 668 as Solved (AI) by a three-human plus Claude team, while the dedicated problem page still appeared to say open. The construction is included as disputed until those sources agree.","full_description":"Existence of Hadamard matrices is classical; order 668 was a remaining computational target. Because Epoch’s index and the problem page disagree, this event is disputed with reduced evidence. Claude’s version is undisclosed, so identity is version-unspecified in the Claude family.","ledger_type":"benefit","primary_domain_id":"23d935bb-b857-4b2b-9471-d568bb848a66","event_status":"disputed","event_date":"2026-08-12T00:00:00.000Z","discovery_date":"2026-08-12T00:00:00.000Z","first_published_date":"2026-08-12T00:00:00.000Z","last_reviewed_date":"2026-08-12T00:00:00.000Z","geographic_scope":"International","affected_population":"Combinatorial design research community","base_impact_tier":2,"base_score":"3.00","attribution_multiplier":"0.4500","evidence_multiplier":"0.2500","realization_multiplier":"0.4000","durability_multiplier":"0.7000","current_event_score":"0.094500","confidence_level":"medium","score_explanation":"A Hadamard matrix of a new order would be notable (tier 2). Human–AI team with unnamed Claude (0.45). Evidence is inconsistent Epoch pages (0.25). Realization is a reported finite matrix, not a converged public record (0.40).","methodology_version_id":"d7881163-fb23-4e71-8625-bac1a8662c0f","original_methodology_version_id":"d7881163-fb23-4e71-8625-bac1a8662c0f","published_at":"2026-08-12T00:00:00.000Z","created_at":"2026-09-13T22:56:05.431Z","updated_at":"2026-09-13T22:56:05.431Z","flags":[],"domain_name":"Mathematics","domain_slug":"mathematics","methodology_version":"0.1"},"contributions":[{"id":"0ad72199-3391-46cf-845f-da2127e55125","event_id":"4c914784-5f72-49d1-95d3-94c0a60ce131","model_id":"059c33b6-fc2e-4d3d-acdb-c0d966ee5e6e","role_description":"Unspecified Claude used by a three-human team in the reported Hadamard 668 construction.","attribution_multiplier":"0.4500","credit_share":"1.0000","contribution_score":"0.094500","attribution_rationale":"Epoch commentary credits a three-human plus Claude team; no Fable/Opus SKU is given, so Claude stays version-unspecified and attribution stays modest.","attribution_confidence":"medium","first_used_date":"2026-08-12T00:00:00.000Z","model_version_if_known":null,"review_status":"approved","created_at":"2026-09-13T22:56:05.431Z","model_slug":"claude","model_name":"Claude","identity_class":"unknown","is_internal":false,"family_name":"Claude","family_slug":"anthropic-claude","organization_name":"Anthropic","organization_slug":"anthropic"}],"sources":[{"id":"9021fcb6-bebf-4bfe-96c3-13bcdd989c5c","event_id":"4c914784-5f72-49d1-95d3-94c0a60ce131","url":"https://epoch.ai/frontiermath/open-problems","canonical_url":"https://epoch.ai/frontiermath/open-problems","source_type":"other","publisher":"Epoch AI","author":null,"publication_date":"2026-08-12T00:00:00.000Z","retrieved_at":"2026-09-13T22:56:05.431Z","title":"FrontierMath Open Problems index","excerpt":null,"content_hash":null,"source_reliability_class":"medium","is_primary_source":true,"is_independent":true,"is_peer_reviewed":false,"archived_url":null,"created_at":"2026-09-13T22:56:05.431Z"},{"id":"1c5590dc-a26b-473e-84bb-f8fec5659930","event_id":"4c914784-5f72-49d1-95d3-94c0a60ce131","url":"https://epoch.ai/frontiermath/open-problems/hadamard","canonical_url":"https://epoch.ai/frontiermath/open-problems/hadamard","source_type":"other","publisher":"Epoch AI","author":null,"publication_date":"2026-08-12T00:00:00.000Z","retrieved_at":"2026-09-13T22:56:05.431Z","title":"Hadamard matrices (FrontierMath Open Problems)","excerpt":null,"content_hash":null,"source_reliability_class":"medium","is_primary_source":true,"is_independent":true,"is_peer_reviewed":false,"archived_url":null,"created_at":"2026-09-13T22:56:05.431Z"}],"claims":[{"id":"9d7575d9-c690-475b-8262-242e03599028","event_id":"4c914784-5f72-49d1-95d3-94c0a60ce131","claim_text":"Epoch’s index/changelog has marked Hadamard order 668 as solved by a three-human plus Claude team.","claim_type":"outcome","claim_status":"supported","confidence_score":null,"created_at":"2026-09-13T22:56:05.431Z","updated_at":"2026-09-13T22:56:05.431Z"},{"id":"631541ac-2631-4e84-ac7e-37793f17db8f","event_id":"4c914784-5f72-49d1-95d3-94c0a60ce131","claim_text":"Epoch’s dedicated Hadamard page and the index currently agree that a matrix is public and verified.","claim_type":"significance","claim_status":"disputed","confidence_score":null,"created_at":"2026-09-13T22:56:05.431Z","updated_at":"2026-09-13T22:56:05.431Z"}],"revisions":[{"id":"63c6e0a5-a9a9-4908-b7dc-4aafeb6a678d","event_id":"4c914784-5f72-49d1-95d3-94c0a60ce131","model_id":null,"previous_score":"0.000000","new_score":"0.094500","previous_factors":{},"new_factors":{"evidence":0.25,"base_score":3,"durability":0.7,"attribution":0.45,"realization":0.4},"change_reason":"Imported events under methodology 0.1.","trigger_type":"editorial_import","trigger_source_ids":null,"reviewer_id":null,"review_status":"published","created_at":"2026-09-13T22:56:05.431Z"}],"secondary":[{"name":"Computer Science","slug":"computer-science"}]},"methodology_version":"0.1"}