In RLVR? Quite easily. And OpenAI has induced hallucinations in o3 with RLVR mistakes, not with a failed pre-training run. They used o4-mini as an example - si

In RLVR? Quite easily. And OpenAI has induced hallucinations in o3 with RLVR mistakes, not with a failed pre-training run. They used o4-mini as an example - similar training to o3 and similar issues. Conversely, they have also designed a post-training system that has successfully reduced hallucinations in GPT-5.