Mysterious 'gpt2-chatbot' AI Model Appears Suddenly, Confuses Experts

An anonymous reader quotes a report from Ars Technica: On Sunday, word began to spread on social media about a new mystery chatbot named "gpt2-chatbot" that appeared in the LMSYS Chatbot Arena. Some people speculate that it may be a secret test version of OpenAI's upcoming GPT-4.5 or GPT-5 large language model (LLM). The paid version of ChatGPT is currently powered by GPT-4 Turbo. Currently, the new model is only available for use through the Chatbot Arena website, although in a limited way. In the site's "side-by-side" arena mode where users can purposely select the model, gpt2-chatbot has a rate limit of eight queries per day -- dramatically limiting people's ability to test it in detail. [...] On Monday evening, OpenAI CEO Sam Altman seemingly dropped a hint by tweeting, "i do have a soft spot for gpt2." [...] OpenAI's fingerprints seem to be all over the new bot. "I think it may well be an OpenAI stealth preview of something," AI researcher Simon Willison told Ars Technica. But what "gpt2" is exactly, he doesn't know. After surveying online speculation, it seems that no one apart from its creator knows precisely what the model is, either. Willison has uncovered the system prompt for the AI model, which claims it is based on GPT-4 and made by OpenAI. But as Willison noted in a tweet, that's no guarantee of provenance because "the goal of a system prompt is to influence the model to behave in certain ways, not to give it truthful information about itself."

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