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---

license: mit
tags:
- pytorch
- safetensors
- threshold-logic
- neuromorphic
---


# threshold-not

The minimal threshold circuit. One neuron, one weight, one bias.

## Circuit

```

      x

      β”‚

      β–Ό

  β”Œβ”€β”€β”€β”€β”€β”€β”€β”

  β”‚ w: -1 β”‚

  β”‚ b:  0 β”‚

  β””β”€β”€β”€β”€β”€β”€β”€β”˜

      β”‚

      β–Ό

   NOT(x)

```

## Mechanism

A threshold neuron fires when its weighted input plus bias reaches zero. NOT uses weight -1 and bias 0:

- Input 0: sum = 0, fires (output 1)
- Input 1: sum = -1, silent (output 0)

The negative weight flips the relationship between input magnitude and firing.

## Parameters

| | |
|---|---|
| Weight | -1 |
| Bias | 0 |
| Total | 2 parameters |

## Optimality

Exhaustive enumeration of all 5 weight configurations at magnitudes 0-1 confirms this circuit is **already at minimum magnitude (1)**. There is exactly one valid configuration at magnitude 1, and no valid configurations exist below it.

## Properties

- Involutive: NOT(NOT(x)) = x
- Foundation for NAND, NOR

## Usage

```python

from safetensors.torch import load_file



w = load_file('model.safetensors')



def not_gate(x):

    return int(x * w['weight'].item() + w['bias'].item() >= 0)

```

## Files

```

threshold-not/

β”œβ”€β”€ model.safetensors

β”œβ”€β”€ model.py

β”œβ”€β”€ config.json

└── README.md

```

## License

MIT