At least 2 of 4 threshold circuit, magnitude 6

README.md

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+---
+license: mit
+tags:
+- pytorch
+- safetensors
+- threshold-logic
+- neuromorphic
+---
+
+# threshold-2outof4
+
+At least 2 of 4 inputs high.
+
+## Function
+
+2outof4(a, b, c, d) = 1 if (a + b + c + d) >= 2, else 0
+
+## Truth Table
+
+| a | b | c | d | sum | out |
+|---|---|---|---|-----|-----|
+| 0 | 0 | 0 | 0 | 0 | 0 |
+| 0 | 0 | 0 | 1 | 1 | 0 |
+| 0 | 0 | 1 | 1 | 2 | 1 |
+| 0 | 1 | 1 | 1 | 3 | 1 |
+| 1 | 1 | 1 | 1 | 4 | 1 |
+
+## Architecture
+
+Single neuron: weights [1, 1, 1, 1], bias -2
+
+Fires when: a + b + c + d - 2 >= 0, i.e., sum >= 2
+
+## Parameters
+
+| | |
+|---|---|
+| Inputs | 4 |
+| Outputs | 1 |
+| Neurons | 1 |
+| Layers | 1 |
+| Parameters | 5 |
+| Magnitude | 6 |
+
+## Usage
+
+```python
+from safetensors.torch import load_file
+import torch
+
+w = load_file('model.safetensors')
+
+def atleast2of4(a, b, c, d):
+    inp = torch.tensor([float(a), float(b), float(c), float(d)])
+    return int((inp @ w['neuron.weight'].T + w['neuron.bias'] >= 0).item())
+
+print(atleast2of4(0, 0, 0, 1))  # 0 (sum=1)
+print(atleast2of4(0, 0, 1, 1))  # 1 (sum=2)
+```
+
+## License
+
+MIT

config.json

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+{
+  "name": "threshold-2outof4",
+  "description": "At least 2 of 4 inputs high",
+  "inputs": 4,
+  "outputs": 1,
+  "neurons": 1,
+  "layers": 1,
+  "parameters": 5
+}

create_safetensors.py

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+import torch
+from safetensors.torch import save_file
+
+weights = {
+    'neuron.weight': torch.tensor([[1.0, 1.0, 1.0, 1.0]], dtype=torch.float32),
+    'neuron.bias': torch.tensor([-2.0], dtype=torch.float32)
+}
+
+save_file(weights, 'model.safetensors')
+
+# Verify
+def atleast2of4(a, b, c, d):
+    inp = torch.tensor([float(a), float(b), float(c), float(d)])
+    return int((inp @ weights['neuron.weight'].T + weights['neuron.bias'] >= 0).item())
+
+print("Verifying 2outof4...")
+errors = 0
+for i in range(16):
+    a, b, c, d = (i >> 3) & 1, (i >> 2) & 1, (i >> 1) & 1, i & 1
+    result = atleast2of4(a, b, c, d)
+    expected = 1 if (a + b + c + d) >= 2 else 0
+    if result != expected:
+        errors += 1
+        print(f"ERROR: {a}{b}{c}{d} -> {result}, expected {expected}")
+
+if errors == 0:
+    print("All 16 test cases passed!")
+else:
+    print(f"FAILED: {errors} errors")
+
+mag = sum(t.abs().sum().item() for t in weights.values())
+print(f"Magnitude: {mag:.0f}")

model.py

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+import torch
+from safetensors.torch import load_file
+
+def load_model(path='model.safetensors'):
+    return load_file(path)
+
+def atleast2of4(a, b, c, d, weights):
+    """Returns 1 if at least 2 of 4 inputs are high"""
+    inp = torch.tensor([float(a), float(b), float(c), float(d)])
+    return int((inp @ weights['neuron.weight'].T + weights['neuron.bias'] >= 0).item())
+
+if __name__ == '__main__':
+    w = load_model()
+    print('2outof4 truth table:')
+    for i in range(16):
+        a, b, c, d = (i >> 3) & 1, (i >> 2) & 1, (i >> 1) & 1, i & 1
+        result = atleast2of4(a, b, c, d, w)
+        print(f'  {a}{b}{c}{d} -> {result}')