ai-forever/Pollux-4B-Judge

TEXT GENERATIONConcurrent Unit Cost:1Model Size:4BQuant:BF16Context Size:32kTool Calling:SupportedPublished:Apr 12, 2026License:mitArchitecture:Transformer0.0K Open Weights Featherless Exclusive Cold

Pollux-4B-Judge is a 4-billion parameter generative language model developed by ai-forever, built upon the Qwen3-4B architecture. This decoder-based model is specifically designed for evaluating the quality of other language models' responses in Russian, predicting numerical scores and detailed textual rationales. It excels at automated LLM performance evaluation for Russian-language tasks, assessing answer quality against specific criteria and rubrics.

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Overview

Pollux-4B-Judge is a 4-billion parameter generative language model from ai-forever, specifically engineered to evaluate the quality of Russian-language LLM responses. Built on the Qwen/Qwen3-4B architecture, it functions as a decoder-based model trained in a sequence-to-sequence fashion.

Key Capabilities

  • Automated LLM Evaluation: Designed to assess the quality of other language models' outputs in Russian.
  • Score and Rationale Generation: Predicts both numerical scores and detailed textual rationales for responses.
  • Criterion-Based Assessment: Evaluates answers based on input instruction, the LLM's response, specific evaluation criteria, and scoring rubrics.
  • Optimized for Russian: Training is specifically optimized using generative tasks and evaluation criteria from the POLLUX dataset.

Performance

Pollux-4B-Judge demonstrates strong performance in evaluating Russian LLM responses. When compared against other models, it achieves a RMSE of 0.568, a macro F1 of 0.705, and a Spearman's rank correlation of 0.744 with expert judgments, outperforming several larger models in these metrics.

Intended Use

This model is best used for assessing text responses against a single, predefined criterion per evaluation run, requiring explicit instruction, the response to be evaluated, the specific criterion, and its corresponding scoring rubrics. It is not designed for simultaneous multi-criteria processing or autonomous criterion determination.