Community claims Rio 3.5 is a rebranded Nex 2.5 PRO

🔑 Enhanced Key Takeaways

• •The Rio 3.5 Open 397B model was developed by IplanRIO, the municipal IT company of Rio de Janeiro, and is a fine-tuned version of Alibaba's Qwen 3.5-397B-A17B, not a completely new model.
• •Rio 3.5 integrates a novel 'SwiReasoning' inference framework, a training-free method that dynamically switches between explicit chain-of-thought reasoning and implicit vector-space reasoning based on information entropy, leading to significant performance improvements on benchmarks like SWE-Bench Pro and IMOAnswerBench.
• •The model is open-source, released under an MIT license, and features a sparse Mixture-of-Experts (MoE) architecture with approximately 397 billion total parameters, activating around 17 billion parameters per token.
• •Despite its impressive benchmark claims, which place it among top open-source and some closed models, independent reproductions of Rio 3.5's benchmarks and repo-local code for SwiReasoning were not found at the time of its release, highlighting the need for verification.
• •A primary limitation for fully utilizing Rio 3.5's capabilities is the requirement for inference engines that support 'soft embedding inputs' for SwiReasoning, which current popular tools like llama.cpp cannot fully support.

🛠️ Technical Deep Dive

🔮 Future ImplicationsAI analysis grounded in cited sources

⏳ Timeline