Ethan Mollick(@emollick):Agreed: GPT-5.6 Pro (which is only available via the chatbot) is the smartest model out there. GPT-5.6 Ultra (the best model in Codex) is not near as powerful on hard tasks. For really hard problems: GPT-5.6 Sol Pro>Fable 5 Ultracode > GPT-5.6 Sol Ultra. (Yes, this is confusing)

Ethan Mollick

@emollick

Professor @Wharton studying AI. New book, Co-Existence, coming October 20. Preorder here: Substack:

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Ethan Mollick@emollick

2026.07.24 04:50

Agreed: GPT-5.6 Pro (which is only available via the chatbot) is the smartest model out there. GPT-5.6 Ultra (the best model in Codex) is not near as powerful on hard tasks. For really hard problems: GPT-5.6 Sol Pro>Fable 5 Ultracode > GPT-5.6 Sol Ultra. (Yes, this is confusing)

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