sige11/div3-classifier

Div3Net — Divisibility-by-3 Classifier

A custom PyTorch classifier that predicts whether a non-negative integer is divisible by 3. Uses a digit histogram encoding: the input is a count of each digit (0-9) plus the total digit count, so the network cannot see digit order — it must rediscover the digit-sum rule.

Architecture

• Input: 10 digit counts + 1 normalized digit-count feature
• Body: layers hidden layers of hidden units, ReLU between them
• Output: single logit
• Params: ~135K per model, ensemble of N models

Checkpoint format

The file div3_model.pt is a dict with:

• format_version: 4
• config: {MAX_DIGITS, hidden, layers, num_models, encoding}
• state_dicts: list of state_dict objects, one per ensemble member

Load with the model.py file from the same project.

Performance

~99.8% on held-out random numbers spanning 1 to 50 digits.

Test

Note: this is just for testing PyTorch.