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threshold-subtractor4bit
phanerozoic/threshold-subtractor4bit
threshold-subtractor4bit is a machine learning model from phanerozoic. Use it for the machine learning task on the model card, and read the license before you ship it in a product. The card lists the license as mit.
4-bit subtractor. Computes A - B (modulo 16) with borrow output.
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.py13.2 KB · 72%
At a glance
- License
- mit
- Access
- Public
- Created
- Jan 23, 2026
- Updated
- Jan 23, 2026
- SHA
- 5f77b998
Model card
From the Hugging Face model README
threshold-subtractor4bit
4-bit subtractor. Computes A - B (modulo 16) with borrow output.
Function
subtractor4bit(A, B) = (A - B) mod 16, borrow_out
Truth Table (selected rows)
| A | B | Diff | Borrow |
|---|---|---|---|
| 7 | 3 | 4 | 0 |
| 5 | 5 | 0 | 0 |
| 3 | 7 | 12 | 1 |
| 0 | 1 | 15 | 1 |
Architecture
Ripple-borrow subtractor using full subtractor units.
For each bit i:
- diff_i = a_i XOR b_i XOR borrow_{i-1}
- borrow_i = majority(NOT(a_i), b_i, borrow_{i-1})
The borrow signal indicates A < B (unsigned comparison).
Parameters
| Inputs | 8 (a3-a0, b3-b0) |
| Outputs | 5 (d3-d0, bout) |
| Neurons | 25 |
| Layers | 8 |
| Parameters | 86 |
| Magnitude | 88 |
Usage
from safetensors.torch import load_file
# See model.py for full implementation
# 7 - 3 = 4
# subtractor4(0,1,1,1, 0,0,1,1) = [0,1,0,0, 0]
# 3 - 7 = 12 (wraps), borrow=1
# subtractor4(0,0,1,1, 0,1,1,1) = [1,1,0,0, 1]
License
MIT
- License
- mit
- Created
- Jan 23, 2026
- Updated
- Jan 23, 2026