Descriptions:
AI researcher Fahd Mirza puts LongCat Flash Prover through its paces in this hands-on review, covering one of the most capable open-source formal mathematics proving models released to date. At 560 billion parameters, Flash Prover is built around a multi-expert architecture where specialized sub-models handle auto-formalization, theorem decomposition, and proof construction, with all outputs verified in real time by Lean 4’s zero-tolerance proof checker—a significant architectural step beyond DeepSeek Prover v2 and InternLM StepProver.
Mirza tests the model across a range of increasingly demanding prompts: a Lean 4 induction proof connecting exponential growth to formal mathematics, a deliberate hallucination trap using the famously unproven Goldbach Conjecture (which the model correctly refuses to fabricate a complete general proof for), and a real-world compound interest inequality requiring strict handling of real number arithmetic. The video also explains two key architectural innovations—HISO, a self-correction mechanism that filters stale or inconsistent training data during long reasoning chains, and the model’s auto-formalization pipeline that converts plain English mathematical statements into formal Lean 4 syntax end to end.
For anyone tracking the state of AI in formal reasoning, this video offers a grounded technical look at how Flash Prover stacks up against current alternatives, with Mirza concluding that its scale, hallucination awareness, and honest acknowledgment of proof boundaries put it ahead of DeepSeek Prover despite an occasionally unstable chat interface. The model weights are available on Hugging Face.
📺 Source: Fahd Mirza · Published March 21, 2026
🏷️ Format: Review
