21 Years Open: Conjecture 176 Joins the Growing List of Opus 5's Pre-2006 Disproofs

Claude Opus 5's third disproof targets a conjecture from August 8, 2005 — making it 21 years old and the oldest conjecture disproved today. The previous disproofs: Conjecture 66 (March 25, 2004, 22 years) and Conjecture 340 (February 18, 2009, 17 years). Combined, Opus 5 has closed 60 years of open-problem history in a single day. The 2004-2009 date range spans the Graffiti.pc collection's most active period (DeLaViña's "Written on the Wall II" era). Each disproof was published with hand-checkable verification and committed to the graffiti-verification GitLab repo, creating a permanent, reproducible record of the counterexamples.