Pollux-4B-Judge

Pollux-4B-Judge is a 4-billion parameter generative language model specifically designed to evaluate the quality of other language models' responses in Russian. The model assesses answer quality given input instruction, specific criteria and rubrics, providing automated LLM performance evaluation for Russian-language tasks.

Model Details

Model Description

Pollux-4B-Judge is an integral component of the POLLUX project, a comprehensive initiative dedicated to evaluating the generative capabilities of Large Language Models (LLMs). At the heart of this project lies the Qwen/Qwen3-4B, which introduces systematic taxonomies for both generative tasks and evaluation criteria, providing quantitative and qualitative assessments of responses from top-tier LLMs.

Built upon the Qwen/Qwen3-4B architecture, Pollux-4B-Judge is a decoder-based 4 billion parameter model trained in a sequence-to-sequence fashion. The model is designed to predict both numerical scores and detailed textual rationales based on the original instruction, the LLM's response, specific evaluation criteria, scoring rubrics, and reference answers when available.

While the model is technically capable of processing any type of instruction and criterion when properly formatted, its training has been specifically optimized using the generative tasks and evaluation criteria derived from the taxonomies established within the POLLUX dataset.

• Model type: decoder
• Language(s) (NLP): Russian
• License: MIT
• Finetuned from model: Qwen/Qwen3-4B

Model Sources

• Repository: POLLUX code base
• Paper: ArXiv preprint

Uses

Direct Use

Pollux-4B-Judge is specifically designed for assessing text responses against a single, predefined criterion per evaluation run. The model operates optimally when provided with all essential components: the source instruction, the response to be evaluated (typically generated by another LLM), the specific evaluation criterion, and its corresponding scoring rubrics.

Out-of-Scope Use

While the model may technically process multiple criteria simultaneously, such usage falls outside its intended design and may yield unpredictable results. Similarly, the model is not designed to function autonomously in determining appropriate evaluation criteria—it requires explicit criterion specification to perform reliable assessments.

For optimal performance and reliable results, users should structure each evaluation session around one criterion at a time, providing all necessary contextual components to enable the model's comprehensive scoring and rationale generation capabilities.

MODEL OUTPUT DISCLAIMER AND LIMITATION OF LIABILITY

All content, responses, and outputs generated by Pollux-4B-Judge (the "Model") are produced through automated computational processes based on statistical patterns learned from pre-training data. Such outputs do not constitute statements, opinions, recommendations, or positions of the model developers, publishers, or affiliated entities (collectively, the "Developers").

The Model's outputs do not represent, reflect, or endorse any views, beliefs, policies, or positions held by the Developers. Generated content should not be interpreted as official statements, advice, or guidance from the Developers.

While the Developers employed appropriate data curation practices during fine-tuning and avoided the intentional inclusion of inappropriate content, the Model's responses may reflect patterns present in the underlying pre-training datasets, which were sourced from publicly available internet content and other large-scale text corpora.

The Developers expressly disclaim responsibility for any content generated by the Model. Users acknowledge that:

• Generated outputs are probabilistic and may contain inaccuracies, biases, or inappropriate content
• The Developers cannot guarantee the accuracy, completeness, or appropriateness of any Model output
• Users assume full responsibility for evaluating and using Model-generated content

Users are solely responsible for reviewing, validating, and determining the appropriateness of any Model-generated content before use or distribution.

How to Get Started with the Model

Install the required packages:

pip install vllm==0.19.0
pip install transformers==5.3.0
pip install openai

Start the vLLM OpenAI-compatible server:

vllm serve ai-forever/Pollux-4B-Judge --tensor-parallel-size 1 --reasoning-parser qwen3

Use the code below to send requests to the running server:

from openai import OpenAI

client = OpenAI(
    base_url="http://localhost:8000/v1",
    api_key="EMPTY",
)

PROMPT_TEMPLATE = """### Задание для оценки:
{instruction}

### Эталонный ответ:
{reference_answer}

### Ответ для оценки:
{answer}

### Критерий оценки:
{criteria_name}

### Шкала оценивания по критерию:
{criteria_rubrics}
"""

instruction = "Сколько будет 2+2?"
reference_answer = "4"
answer = "Будет 4"
criteria_name = "Правильность ответа"
criteria_rubrics = """0: Дан неправильный ответ или ответ отсутствует.

1: Ответ модели неполный (не на все вопросы задания получен ответ, в формулировке ответа отсутствует часть информации).

2: Ответ модели совпадает с эталонным или эквивалентен ему."""

prompt = PROMPT_TEMPLATE.format(
    instruction=instruction,
    reference_answer=reference_answer,
    answer=answer,
    criteria_name=criteria_name,
    criteria_rubrics=criteria_rubrics,
)
response = client.chat.completions.create(
    model="ai-forever/Pollux-4B-Judge",
    messages=[{"role": "user", "content": prompt}],
    max_tokens=512,
    temperature=0.0,
)

score = response.choices[0].message.content.strip()
reasoning = response.choices[0].message.reasoning

print(score)
print(reasoning)

Testing Data

For testing data we employed the POLLUX dataset. Note this provides both in- and out-of-domain evaluation as some of the tasks and criteria are absent in training data.

Metrics

We employed RMSE, macro F1, and Spearman’s rank correlation with expert judgements to assess the performance of Pollux-4B-Judge and compare it with those of the reference models.

RMSE offers a high degree of interpretability, as it is measured on the same scale as the annotation – specifically, in points. Macro F1 captures score classification quality across labels, while Spearman’s rank correlation allows to quantify the degree of monotonic association between the two rankings of models outputs and to demonstrate how consistently the LLM-as-Judge reproduces the relative ordering of output quality as established by human experts.

Results

We report aggregate evaluation results in the table below.

Citation

BibTeX:

@misc{martynov2025eyejudgementdissectingevaluation,
      title={Eye of Judgement: Dissecting the Evaluation of Russian-speaking LLMs with POLLUX}, 
      author={Nikita Martynov and Anastasia Mordasheva and Dmitriy Gorbetskiy and Danil Astafurov and Ulyana Isaeva and Elina Basyrova and Sergey Skachkov and Victoria Berestova and Nikolay Ivanov and Valeriia Zanina and Alena Fenogenova},
      year={2025},
      eprint={2505.24616},
      archivePrefix={arXiv},
      primaryClass={cs.CL},
      url={https://arxiv.org/abs/2505.24616}, 
}