On July 23, 2026, xAI's Grok 4.5 constructed a counterexample in eight minutes during an informal internal team chat on a Slack channel, overturning a classic graph theory conjecture that had puzzled mathematicians for roughly 30 years. The overturned Dinitz-Garg-Goemans conjecture, in graph theory and combinatorial optimization, was disproven when Grok 4.5 found a counterexample graph showing a fractional flow cost of 58, while any unsplittable flow with capacity violation not exceeding 15 had a cost of at least 60. Founder Elon Musk reposted the news on X, commenting: "Grok 4.5 just solved a ~30 year old open graph theory conjecture." According to Tron founder Justin Sun, an AI agent named Capy, running on Grok 4.5 Medium, proactively attempted to solve the problem after the team shared an original math problem posted by user Dmitry Rybin. Rybin revealed that this discovery was initially made through conversations with OpenAI's GPT-5, meaning both top-tier models delivered valid solutions in rapid succession. The breakthrough comes amid intensified US-China AI model competition, as Chinese AI unicorn Moonshot AI had recently released its flagship model, Kimi K3, drawing attention from Musk.