wcamon/circus-0.4-t9

VISIONConcurrent Unit Cost:1Model Size:4.5BQuant:BF16Context Size:32kTool Calling:SupportedPublished:Aug 9, 2026License:apache-2.0Architecture:Transformer Open Weights Featherless Exclusive Cold

wcamon/circus-0.4-t9 is a 4.5 billion parameter language model developed by Wei-Ciao Wu, derived from Agents-A1-4B. It features a novel additive two-plane 9-level quantization grid, constraining every linear weight to achieve approximately 3.67 bits per weight. This model focuses on demonstrating an advanced quantization recovery methodology and the additive bit-plane form for efficient inference, maintaining high retention across various benchmarks like MMLU and GSM8k.

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Overview

wcamon/circus-0.4-t9 is a 4.5 billion parameter language model based on the Agents-A1-4B architecture, developed by Wei-Ciao Wu. Its core innovation lies in its additive two-plane 9-level quantization grid, where every linear weight is constrained to a specific set of values, achieving an approximate density of 3.67 bits per weight. This approach enables the potential for addition-only matmul kernels, similar to BitNet-style models, offering significant inference efficiency.

Key Characteristics

  • Advanced Quantization: Utilizes a unique 9-level additive bit-plane quantization scheme, represented by two ternary planes. This allows for a compact representation (1.7 GB true quantized artifact vs. 8.5 GB bf16 materialization).
  • High Retention: Despite aggressive quantization, the model demonstrates strong performance retention, achieving over 90% retention on tasks like GSM8k (96.3%), MMLU (99.0%), and HumanEval (93.6%) compared to its bf16 base.
  • Novel Recovery Methodology: The model was produced using a sophisticated recovery recipe involving GPTQ-style per-layer initialization, sliding-window soft-anneal reconstruction, and light polish with scale-only logit KD. This methodology is a key contribution, particularly for low-bit recovery.
  • Dual Artifacts: Ships with both a bf16 materialized version for immediate use with transformers and a bitplanes_k2_c0.6.npz file representing the true bit-exact quantized artifact.

Good For

  • Research in Quantization: Ideal for researchers exploring advanced quantization techniques, particularly additive bit-plane forms and their recovery methodologies.
  • Efficient Inference Development: Provides a foundation for developing and testing addition-only matmul kernels for highly efficient, low-bit inference.
  • Understanding Low-Bit Model Behavior: Offers insights into the trade-offs and challenges of achieving high performance with very low bit-width models, especially regarding assignment quality and recovery bottlenecks.