OpenAI’s new o3 model has achieved a breakthrough performance on the ARC-AGI benchmark, demonstrating advanced reasoning capabilities through a ‘private chain of thought’ mechanism. The model searches over natural language programs to solve tasks, with a significant increase in compute leading to a substantial improvement in its score. This approach highlights the use of deep learning to guide program search, pushing the boundaries beyond simple next-token prediction. The o3 model’s ability to recombine knowledge at test time through program execution suggests a significant step towards more general AI capabilities.