File size: 3,103 Bytes
4754707 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 | """v31: Shared-weight recurrent depth.
Physically N distinct blocks; each block is applied K times sequentially.
Effective depth = N·K with only N params. Tests whether discrete forward
passes benefit disproportionately from depth at the same param cost.
"""
import math
import torch
import torch.nn as nn
import torch.nn.functional as F
from model import sign_ste, BinaryEmbedding
from model_v18 import BitBlockV18, IntBinaryAttention
class BitLMv31(nn.Module):
def __init__(self, vocab_size=128, d_model=256, n_unique_blocks=4, block_repeat=2,
n_heads=8, d_ff=512, max_seq_len=256):
super().__init__()
self.vocab_size = vocab_size
self.d_model = d_model
self.n_unique_blocks = n_unique_blocks
self.block_repeat = block_repeat
self.n_layers = n_unique_blocks * block_repeat # effective depth
self.max_seq_len = max_seq_len
self.embed = BinaryEmbedding(vocab_size, d_model)
# Only N unique block parameter sets, but we apply each K times.
self.unique_blocks = nn.ModuleList([
BitBlockV18(d_model, n_heads, d_ff) for _ in range(n_unique_blocks)
])
self.out_codebook = nn.Parameter(torch.randn(vocab_size, d_model) * 0.02)
self.logit_scale = nn.Parameter(torch.tensor(1.0 / math.sqrt(d_model)))
self.out_bias = nn.Parameter(torch.zeros(vocab_size))
def forward(self, idx, targets=None):
x = self.embed(idx)
for blk in self.unique_blocks:
for _ in range(self.block_repeat):
x = blk(x)
W_out = sign_ste(self.out_codebook)
scores = torch.matmul(x, W_out.t())
logits = scores * self.logit_scale + self.out_bias
loss = None
if targets is not None:
loss = F.cross_entropy(logits.view(-1, self.vocab_size), targets.view(-1))
return logits, loss
@torch.no_grad()
def generate(self, idx, max_new_tokens=200, temperature=1.0, top_k=None):
self.eval()
for _ in range(max_new_tokens):
idx_cond = idx[:, -self.max_seq_len:]
logits, _ = self(idx_cond)
logits = logits[:, -1, :] / max(temperature, 1e-5)
if top_k is not None:
v, _ = torch.topk(logits, top_k)
logits[logits < v[:, [-1]]] = -float('inf')
probs = F.softmax(logits, dim=-1)
nxt = torch.multinomial(probs, num_samples=1)
idx = torch.cat([idx, nxt], dim=1)
return idx
if __name__ == '__main__':
from model_v16 import set_gumbel_tau
set_gumbel_tau(0.5)
# Match v17's 5M with 4 unique blocks × 2 repeat = 8 effective layers
m = BitLMv31(vocab_size=128, d_model=256, n_unique_blocks=4, block_repeat=2,
n_heads=8, d_ff=512)
n = sum(p.numel() for p in m.parameters())
print(f'v31 (4 blocks × 2 repeat): {n:,} params ({n/1e6:.2f}M)')
x = torch.randint(0, 128, (2, 64))
y = torch.randint(0, 128, (2, 64))
logits, loss = m(x, y)
loss.backward()
print(f' loss={loss.item():.3f}, backward OK')
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