Remove closed-loop classes (CerebellarGate, LossPredictor, EmotionGate) from forward_model.py
Browse files- forward_model.py +2 -87
forward_model.py
CHANGED
|
@@ -1,12 +1,7 @@
|
|
| 1 |
-
"""Forward models
|
| 2 |
|
| 3 |
ForwardModel: per-position MLP. Structurally blind to cross-position effects.
|
| 4 |
-
TransformerForwardModel: small transformer
|
| 5 |
-
position-blind — the residual captures computational novelty, not attention's
|
| 6 |
-
existence. Architecture mirrors the cerebellar circuit:
|
| 7 |
-
- Causal attention with compressed projections (pontine relay)
|
| 8 |
-
- MLP expansion (granule cell combinatorial coding)
|
| 9 |
-
- Linear readout (Purkinje cell)
|
| 10 |
"""
|
| 11 |
|
| 12 |
import math
|
|
@@ -82,86 +77,6 @@ class ForwardBlock(nn.Module):
|
|
| 82 |
return x
|
| 83 |
|
| 84 |
|
| 85 |
-
class CerebellarGate(nn.Module):
|
| 86 |
-
"""Learned gated projection for injecting forward model predictions.
|
| 87 |
-
|
| 88 |
-
Zero-initialized so the injection starts at exactly zero.
|
| 89 |
-
The projection learns to transform the forward model's prediction
|
| 90 |
-
into a useful signal for the main model's residual stream (thalamic
|
| 91 |
-
relay analog). Injection magnitude grows from zero as training
|
| 92 |
-
discovers useful structure.
|
| 93 |
-
"""
|
| 94 |
-
|
| 95 |
-
def __init__(self, d_model: int):
|
| 96 |
-
super().__init__()
|
| 97 |
-
self.projection = nn.Linear(d_model, d_model)
|
| 98 |
-
nn.init.zeros_(self.projection.weight)
|
| 99 |
-
nn.init.zeros_(self.projection.bias)
|
| 100 |
-
print(f"CerebellarGate: {sum(p.numel() for p in self.parameters())/1e3:.1f}K "
|
| 101 |
-
f"parameters (d_model={d_model})")
|
| 102 |
-
|
| 103 |
-
def forward(self, fwd_pred):
|
| 104 |
-
return self.projection(fwd_pred)
|
| 105 |
-
|
| 106 |
-
def injection_norm(self):
|
| 107 |
-
return self.projection.weight.norm().item()
|
| 108 |
-
|
| 109 |
-
|
| 110 |
-
class LossPredictor(nn.Module):
|
| 111 |
-
"""Predicts per-token loss from early-layer activations (emotion analog).
|
| 112 |
-
|
| 113 |
-
Returns both a low-dimensional embedding (for injection via EmotionGate)
|
| 114 |
-
and a scalar loss prediction (for training via MSE against actual CE).
|
| 115 |
-
When embed_dim=1, the embedding IS the scalar prediction.
|
| 116 |
-
When embed_dim>1, a linear head maps the embedding to a scalar for training,
|
| 117 |
-
but the full embedding is what gets injected.
|
| 118 |
-
"""
|
| 119 |
-
|
| 120 |
-
def __init__(self, d_model: int, embed_dim: int = 1, hidden: int = 128):
|
| 121 |
-
super().__init__()
|
| 122 |
-
self.embed_dim = embed_dim
|
| 123 |
-
self.encoder = nn.Sequential(
|
| 124 |
-
nn.LayerNorm(d_model),
|
| 125 |
-
nn.Linear(d_model, hidden),
|
| 126 |
-
nn.GELU(),
|
| 127 |
-
nn.Linear(hidden, embed_dim),
|
| 128 |
-
)
|
| 129 |
-
self.head = nn.Linear(embed_dim, 1) if embed_dim > 1 else None
|
| 130 |
-
n_params = sum(p.numel() for p in self.parameters())
|
| 131 |
-
print(f"LossPredictor: {n_params/1e3:.1f}K parameters "
|
| 132 |
-
f"(d_model={d_model}, embed_dim={embed_dim}, hidden={hidden})")
|
| 133 |
-
|
| 134 |
-
def forward(self, x):
|
| 135 |
-
embed = self.encoder(x) # (B, T, embed_dim)
|
| 136 |
-
if self.head is not None:
|
| 137 |
-
loss_pred = self.head(embed).squeeze(-1) # (B, T)
|
| 138 |
-
else:
|
| 139 |
-
loss_pred = embed.squeeze(-1) # (B, T)
|
| 140 |
-
return embed, loss_pred
|
| 141 |
-
|
| 142 |
-
|
| 143 |
-
class EmotionGate(nn.Module):
|
| 144 |
-
"""Learned projection for injecting evaluative signals into the residual stream.
|
| 145 |
-
|
| 146 |
-
Zero-initialized like CerebellarGate. Projects from a low-dimensional
|
| 147 |
-
evaluative embedding to full residual stream dimensionality.
|
| 148 |
-
"""
|
| 149 |
-
|
| 150 |
-
def __init__(self, embed_dim: int, d_model: int):
|
| 151 |
-
super().__init__()
|
| 152 |
-
self.projection = nn.Linear(embed_dim, d_model)
|
| 153 |
-
nn.init.zeros_(self.projection.weight)
|
| 154 |
-
nn.init.zeros_(self.projection.bias)
|
| 155 |
-
print(f"EmotionGate: {sum(p.numel() for p in self.parameters())/1e3:.1f}K "
|
| 156 |
-
f"parameters (embed_dim={embed_dim}, d_model={d_model})")
|
| 157 |
-
|
| 158 |
-
def forward(self, embed):
|
| 159 |
-
return self.projection(embed)
|
| 160 |
-
|
| 161 |
-
def injection_norm(self):
|
| 162 |
-
return self.projection.weight.norm().item()
|
| 163 |
-
|
| 164 |
-
|
| 165 |
class TransformerForwardModel(nn.Module):
|
| 166 |
def __init__(self, d_model: int, d_head: int = 64, n_head: int = 1,
|
| 167 |
n_layer: int = 1, mlp_mult: float = 2, block_size: int = 128,
|
|
|
|
| 1 |
+
"""Forward models for predicting transformer activations.
|
| 2 |
|
| 3 |
ForwardModel: per-position MLP. Structurally blind to cross-position effects.
|
| 4 |
+
TransformerForwardModel: small transformer with capacity bottleneck.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 5 |
"""
|
| 6 |
|
| 7 |
import math
|
|
|
|
| 77 |
return x
|
| 78 |
|
| 79 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 80 |
class TransformerForwardModel(nn.Module):
|
| 81 |
def __init__(self, d_model: int, d_head: int = 64, n_head: int = 1,
|
| 82 |
n_layer: int = 1, mlp_mult: float = 2, block_size: int = 128,
|