| |
| """J-SPACE analyzer — advanced (after Anthropic 'A global workspace in language models', Jul 2026). |
| |
| Beyond the logit-lens primitive. Implements the real machinery to identify & score a model's reasoning |
| 'global workspace', as a DATA-FREE genetic-merge fitness: |
| |
| 1. FUTURE-INFLUENCE JACOBIAN (the actual J-lens signal, not next-token logit-lens): |
| G_l = d(total future NLL)/d(hidden_l) [seq,hid]. Row i = the direction in which position i's |
| activation steers ALL future outputs (causal). This is "the pattern that makes the model likely to |
| say things later" — the workspace read/write signal. |
| |
| 2. J-SPACE SUBSPACE via SVD of G_l per layer: |
| - energy_conc : fraction of future-influence energy in the top-k singular directions. |
| - eff_rank : exp(entropy of normalized singular values) — a LOW effective rank = a small, |
| coherent workspace (<10% signature). Reported as frac = eff_rank/hidden. |
| - The top singular vectors ARE the J-space directions at that layer. |
| |
| 3. PLANNING via the lens: how EARLY the model resolves future tokens (front-loaded competence), |
| base=layer1 (skip embeddings). A rich workspace reasons in mid layers, not just at the end. |
| |
| 4. CAUSAL INTERVENTION: project the J-space subspace OUT at a mid layer (hook) and measure the |
| reasoning-NLL increase vs a random-subspace-of-equal-rank control. If ablating the workspace hurts |
| reasoning MORE than a random subspace, the identified subspace is causally the reasoning substrate. |
| |
| 5. Composite FITNESS = f(front_load, workspace concentration, causal necessity). All data-free |
| (fixed reasoning probe set). CPU / float32. |
| """ |
| import sys, math, torch |
| from transformers import AutoModelForCausalLM, AutoTokenizer |
| MODEL = "/Users/kikocisneros/coco_ppl/attn_longctx/model"; DEV = "cpu" |
| tok = AutoTokenizer.from_pretrained(MODEL) |
| def load(): return AutoModelForCausalLM.from_pretrained(MODEL, dtype=torch.float32).to(DEV).eval() |
|
|
| PROBES = [ |
| "Q: If a train goes 60 km in 1 hour, how far in 3 hours? 60 times 3 equals", |
| "Q: Ana has 5 apples, buys 7 more, gives 3 away. 5 plus 7 is 12, minus 3 is", |
| "Q: A spider has 8 legs. How many legs do 3 spiders have? 8 times 3 is", |
| "The opposite of hot is cold. The opposite of up is down. The opposite of fast is", |
| "Paris is to France as Rome is to", |
| ] |
|
|
| |
| class Tap: |
| def __init__(self, model): |
| self.model = model; self.L = model.config.num_hidden_layers |
| self.h = {}; self.handles = []; self.intervene = None |
| def __enter__(self): |
| for l, lyr in enumerate(self.model.model.layers): |
| self.handles.append(lyr.register_forward_hook(self._mk(l))) |
| return self |
| def _mk(self, l): |
| def hook(m, i, o): |
| hs = o[0] if isinstance(o, tuple) else o |
| if self.intervene and self.intervene[0] == l: |
| Q = self.intervene[1] |
| hs2 = hs - (hs @ Q) @ Q.transpose(-1, -2) |
| hs = hs2 |
| return (hs2,) + o[1:] if isinstance(o, tuple) else hs2 |
| if hs.requires_grad: |
| hs.retain_grad(); self.h[l] = hs |
| return hook |
| def __exit__(self, *a): |
| for h in self.handles: h.remove() |
|
|
| def influence_jacobian(model, ids): |
| """G_l = d(total next-token NLL)/d(hidden_l) for each layer -> {l: [seq,hid]} (future-influence dirs).""" |
| with Tap(model) as tap: |
| out = model(ids) |
| loss = torch.nn.functional.cross_entropy(out.logits[0, :-1], ids[0, 1:], reduction="sum") |
| loss.backward() |
| G = {l: tap.h[l].grad[0].detach().clone() for l in range(tap.L) if tap.h[l].grad is not None} |
| model.zero_grad(set_to_none=True) |
| return G |
|
|
| def subspace_stats(G_l, k=8): |
| """SVD of the future-influence matrix [seq,hid] -> workspace concentration + effective rank + top dirs.""" |
| U, S, Vh = torch.linalg.svd(G_l.float(), full_matrices=False) |
| s = S / (S.sum() + 1e-9) |
| energy_topk = s[:k].sum().item() |
| ent = -(s * (s + 1e-12).log()).sum().item() |
| eff_rank = math.exp(ent) |
| return {"energy_topk": energy_topk, "eff_rank_frac": eff_rank / G_l.shape[1], |
| "dirs": Vh[:k].transpose(0, 1)} |
|
|
| def frontload_and_final(model, ids): |
| L = model.config.num_hidden_layers; norm, head = model.model.norm, model.lm_head |
| with torch.no_grad(): |
| hs = model(ids, output_hidden_states=True).hidden_states |
| tgt = ids[0, 1:]; lp = [] |
| for l in range(L+1): |
| ll = head(norm(hs[l][0][:-1])).float() |
| lp.append(torch.log_softmax(ll, -1).gather(1, tgt.unsqueeze(1)).squeeze(1).mean().item()) |
| base, final = lp[1], lp[-1] |
| c = [max(0., min(1.2, (v - base) / (final - base + 1e-6))) for v in lp] |
| return sum(c[1:]) / L, final |
|
|
| @torch.no_grad() |
| def reasoning_nll(model, ids, intervene=None): |
| with Tap(model) as tap: |
| tap.intervene = intervene |
| out = model(ids) |
| return torch.nn.functional.cross_entropy(out.logits[0, :-1], ids[0, 1:]).item() |
|
|
| def causal_necessity(model, ids, layer, k=8): |
| """Ablate the J-space subspace at `layer` vs a random subspace of equal rank -> reasoning-NLL delta.""" |
| G = influence_jacobian(model, ids) |
| if layer not in G: return 0.0 |
| Q = subspace_stats(G[layer], k)["dirs"] |
| Qr, _ = torch.linalg.qr(torch.randn_like(Q)) |
| base = reasoning_nll(model, ids) |
| js = reasoning_nll(model, ids, intervene=(layer, Q)) |
| rnd = reasoning_nll(model, ids, intervene=(layer, Qr)) |
| return (js - base) - (rnd - base) |
|
|
| def fitness(model, verbose=False): |
| L = model.config.num_hidden_layers; mid = L // 2 |
| fl, fc, et, er, cn = [], [], [], [], [] |
| for p in PROBES: |
| ids = tok(p, return_tensors="pt").input_ids.to(DEV) |
| a, b = frontload_and_final(model, ids); fl.append(a); fc.append(b) |
| G = influence_jacobian(model, ids) |
| st = subspace_stats(G[mid]); et.append(st["energy_topk"]); er.append(st["eff_rank_frac"]) |
| cn.append(causal_necessity(model, ids, mid)) |
| r = {"frontload": sum(fl)/len(fl), "final_comp": sum(fc)/len(fc), |
| "ws_energy_topk": sum(et)/len(et), "ws_effrank_frac": sum(er)/len(er), |
| "causal_necessity": sum(cn)/len(cn)} |
| |
| r["JSPACE_FITNESS"] = (r["frontload"] + r["ws_energy_topk"] - r["ws_effrank_frac"] |
| + 0.1 * r["causal_necessity"] + 0.1 * r["final_comp"]) |
| if verbose: |
| for k, v in r.items(): print(f" {k:18s} = {v:+.4f}") |
| return r |
|
|
| if __name__ == "__main__": |
| print("=== J-SPACE (advanced) on clean 0.5B ==="); fitness(load(), verbose=True) |
| print("JSPACE_ADV_DONE") |
|
|