Initial commit: ept — backprop-free equilibrium transformer (EP)

Code (ep_run/), organized docs (docs/{method,campaign,hardware,outreach,paper}),
analysis scripts (scripts/), ONBOARDING.md entry point. Large data/checkpoints
git-ignored (share separately).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014FAPDWQ49M5Ye3NpTndTpn

1 files changed, 38 insertions, 0 deletions

diff --git a/ep_run/spec_bifurcation.py b/ep_run/spec_bifurcation.py
new file mode 100644
index 0000000..aca7629
--- /dev/null
+++ b/ep_run/spec_bifurcation.py
@@ -0,0 +1,38 @@
+import torch, glob, re, math, pickle
+from pathlib import Path
+import lt_ep_train as L
+from lt_ep_train import EQBlock
+L.DD = Path('data/tinystories_bpe')
+L.vocab = pickle.load(open(L.DD/'meta.pkl','rb'))['vocab_size']
+dev='cuda'; eps=0.1; B=8; T=256; N=800
+torch.manual_seed(1234)                       # FIXED batch across all ckpts
+idx, y = L.get_batch('val', B, T)
+idx = idx.to(dev) if hasattr(idx,'to') else idx
+def measure(ckpt):
+    blk = EQBlock(512,16,256,256, s=1.0, c=1.0, attn_mode='thick'); blk.qknorm=True
+    ck = torch.load(ckpt, map_location=dev)
+    with torch.no_grad():
+        for p,w in zip(blk.allp, ck['allp']): p.copy_(w.to(dev))
+        xin = blk.embed(idx).detach(); z = xin.clone(); ress=[]
+        for t in range(N):
+            z2 = z + eps*blk.force(z, xin).detach()
+            r = (z2-z).norm().item()/(z.norm().item()+1e-9); ress.append(r); z=z2
+            if (not math.isfinite(r)) or r>1e2: break
+    win=[ress[i] for i in range(len(ress)) if 1e-6<ress[i]<1e-1] or ress[-200:]
+    rats=[win[i+1]/win[i] for i in range(len(win)-1) if win[i]>0]
+    rho = math.exp(sum(math.log(x) for x in rats)/len(rats)) if rats else float('nan')
+    return rho, ress[-1], len(ress)
+valmap={}
+for l in open('runs/ep_redx.log'):
+    if l.startswith('step'):
+        m=re.search(r'step\s+(\d+)/.*val CE ([\d.]+)', l)
+        if m: valmap[int(m.group(1))]=m.group(2)
+print("=== BIFURCATION PROBE — free-phase contraction ratio rho (fixed batch, 800 relax steps) ===")
+print("rho<1 contractive | rho->1 marginal | rho>=1 divergent ; final_res = floor reached")
+r,fr,n = measure('runs/bptt_final.pt'); print(f"REF  BPTT(val~1.83): rho={r:.4f}  final_res={fr:.2e}  steps={n}")
+print("redx approach to blowup:")
+for ck in sorted(glob.glob('runs/redx_traj/s*.pt'), key=lambda p:int(re.search(r's(\d+)',p).group(1))):
+    step=int(re.search(r's(\d+)',ck).group(1))
+    try: r,fr,n = measure(ck); print(f"  step {step:5d} (val {valmap.get(step,'?')}): rho={r:.4f}  final_res={fr:.2e}  steps={n}")
+    except Exception as e: print(f"  step {step:5d}: ERR {repr(e)[:80]}")
+print("=== DONE ===")