---
library_name: transformers
pipeline_tag: text-classification
tags:
  - transformers
  - pytorch
  - text-classification
  - synthetic-data
  - parity
license: mit
---

# Is Even

`Is Even` is a tiny decoder-only transformer trained on chat-formatted synthetic data from SnurfyAI that predicts whether a decimal input is even.

This repository contains the published model weights and metadata for the released checkpoint.

## What The Model Does

- Input: a decimal numeral rendered inside a fixed ChatML prompt
- Output: `true` for even numbers and `false` for odd numbers
- Tokenization: strict digit-level tokenization with a tiny fixed vocabulary

The task is mathematically determined by the final decimal digit, but the model was trained as a small transformer classifier on synthetic examples.

## Prompt Format

```text
<|im_start|>user
123456<|im_end|>
<|im_start|>assistant
```

The expected completion label is `true` or `false`.

## Training Code

You can train the model yourself using the official SnurfyAI training codebase:

- [SnurfyAI Is Even Core](https://github.com/SnurfyAI/is-even)

The repository contains the code needed to generate the dataset, train the model, and benchmark saved checkpoints.


## Research Paper

- [A Microscopic Study of Decimal Parity in a Tiny Causal Transformer](https://ai.snurfy.net/research/is-even)

The accompanying paper analyzes the model’s generalization behavior, attention structure, and causal dependence on the final digit.