ssurface/qwen3-4b-gdpo-length-sft-l2

TEXT GENERATIONConcurrent Unit Cost:1Model Size:4BQuant:BF16Context Size:32kTool Calling:SupportedPublished:Jul 1, 2026License:apache-2.0Architecture:Transformer Open Weights Featherless Exclusive Cold

The ssurface/qwen3-4b-gdpo-length-sft-l2 model is a 4 billion parameter Qwen3-based causal language model developed by ssurface, fine-tuned for compressed chain-of-thought reasoning at a 'Level 2 (Concise)' output. It utilizes a SFT then GRPO training pipeline with a new reward mechanism to optimize for concise reasoning. This model is specifically designed for tasks requiring efficient and condensed problem-solving explanations within its 32768 token context length.

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Model Overview

The ssurface/qwen3-4b-gdpo-length-sft-l2 is a 4 billion parameter model built upon the Qwen3-4B-Instruct architecture. It has undergone a specialized fine-tuning process to excel in compressed chain-of-thought reasoning, specifically targeting a 'Level 2 (Concise)' output style.

Key Capabilities

  • Concise Chain-of-Thought Reasoning: Optimized to provide condensed and efficient reasoning steps, rather than verbose explanations.
  • GRPO Fine-tuning: Leverages a SFT (Supervised Fine-Tuning) followed by GRPO (Generalized Reinforcement Learning from Human Feedback) with a novel reward function to achieve its concise output style.
  • Qwen3 Base: Benefits from the foundational capabilities of the Qwen3-4B-Instruct model.

Training Pipeline

The model's unique capabilities stem from its multi-stage training:

  1. Base Model: Started with Qwen/Qwen3-4B-Instruct-2507.
  2. SFT LoRA: Fine-tuned using LoRA (Low-Rank Adaptation) with ssurface/qwen3-4b-cot-compress-l2.
  3. GRPO with New Reward: Further optimized using GRPO with a custom reward mechanism to reinforce concise reasoning.

Good For

  • Applications requiring efficient and brief reasoning outputs.
  • Scenarios where detailed, step-by-step explanations need to be condensed.
  • Tasks that benefit from a 'Level 2 (Concise)' problem-solving approach.