GLM-5.1 vs OpenMythos

GLM-5.1 is Z.ai's (formerly Zhipu AI) open-weight model released April 7, 2026 under the MIT license. It's a 744-billion-parameter Mixture-of-Experts architecture with 40 billion active parameters per token, a 200K-token context window, and a 131K maximum output length — and it became the first open-source model ever to lead SWE-bench Pro, scoring 58.4% versus Claude Opus 4.6's 57.3%. The training story is almost as remarkable as the performance. GLM-5.1 was trained entirely on approximately 100,000 Huawei Ascend 910B chips using the MindSpore framework — no Nvidia hardware was used at any point. That makes it one of the first frontier-tier models to demonstrate that the CUDA monoculture isn't technically mandatory for training state-of-the-art models. Z.ai became the first publicly traded foundation model company via a Hong Kong IPO in January 2026 (~$558M raised). The model is free to download from HuggingFace and also available via API at $0.95 per million input tokens. In agentic demonstrations, it has run autonomously for eight hours straight — 655 planning and execution iterations — without human checkpoints.

OpenMythos is a community-driven theoretical reconstruction of Claude Mythos's suspected architecture, implementing a Recurrent-Depth Transformer (RDT) — a looped transformer that recycles layers multiple times per forward pass for deeper reasoning without massive parameter growth. The project drew 10,100 GitHub stars in its first week, reflecting intense developer curiosity about what's powering Anthropic's latest generation models. The architecture has three stages: a Prelude (initial layers), a Recurrent Block (looped up to 32 times with shared weights), and a Coda (final layers). Rather than stacking hundreds of unique layers, the recurrent block runs the same weights multiple times with learned injection parameters updating hidden states between loops — enabling implicit chain-of-thought reasoning in continuous latent space without generating intermediate tokens. The project supports Grouped Query Attention (GQA) with optional Flash Attention 2, Multi-Latent Attention (MLA), and sparse MoE with routed and shared experts. Model scales range from 1B to 1T parameters. The key claim is that RDT achieves reasoning depth comparable to fixed-depth models with far more parameters, since computational complexity scales with loop iterations rather than layer count. This would explain how Claude Mythos achieves strong reasoning performance without the extreme parameter counts of brute-force scaling — though Anthropic has neither confirmed nor denied the architecture.