Trajectory-Certified Contractive RNN / bench_experiment.py

✓✓ Beats tuned baseline

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  1import sys, json, random
  2from pathlib import Path
  3import numpy as np
  4import torch
  5
  6sys.path.insert(0, '/home/maxwelhelp/all/math2nn')
  7from bench import get_dataset, make_model, train_model, evaluate, sweep_baseline, make_report
  8
  9SEEDS = tuple(range(8))
 10# Union is shared by baseline and idea; baseline sweep includes all idea lrs.
 11LRS = [1e-3, 3e-3, 6e-3]
 12EPOCHS = 20
 13BATCH = 128
 14
 15
 16def seed_all(seed):
 17    random.seed(seed); np.random.seed(seed); torch.manual_seed(seed)
 18    if torch.cuda.is_available():
 19        torch.cuda.manual_seed_all(seed)
 20
 21
 22def recurrent_weight(net):
 23    # bench rnn_small uses nn.RNN; robustly find the recurrent hidden-hidden matrix.
 24    for name, p in net.named_parameters():
 25        if 'weight_hh' in name:
 26            return p
 27    raise RuntimeError('recurrent weight not found')
 28
 29
 30def project_certificate(net, radius=0.88):
 31    """Projection implementing a conservative sector certificate for tanh.
 32    Since tanh is 1-Lipschitz, ||W_hh||_2 <= radius gives a common Euclidean
 33    quadratic Lyapunov certificate: V(next)-V <= (rho^2-1)||x||^2 + input terms.
 34    """
 35    with torch.no_grad():
 36        w = recurrent_weight(net)
 37        s = torch.linalg.matrix_norm(w, ord=2)
 38        if torch.isfinite(s) and s > radius:
 39            w.mul_(radius / s)
 40        return float(min(float(s), radius))
 41
 42
 43def train_idea(seed, lr, radius=0.88, return_model=False):
 44    seed_all(seed)
 45    ds = get_dataset('dynamics', seed, n_train=400, n_test=400)
 46    net = make_model('rnn_small', ds['input_shape'], ds['out_dim'])
 47    norms = []
 48    # This is a modified training loop because certification is the intervention.
 49    device = 'cuda' if torch.cuda.is_available() else 'cpu'
 50    try:
 51        net = net.to(device)
 52        opt = torch.optim.Adam(net.parameters(), lr=lr)
 53        lossf = torch.nn.MSELoss()
 54        x, y = ds['xtr'].to(device), ds['ytr'].to(device)
 55        for _ in range(EPOCHS):
 56            net.train(); perm = torch.randperm(len(x), device=device)
 57            for i in range(0, len(x), BATCH):
 58                ix = perm[i:i+BATCH]
 59                loss = lossf(net(x[ix]), y[ix])
 60                opt.zero_grad(); loss.backward(); opt.step()
 61                project_certificate(net, radius)
 62            norms.append(float(torch.linalg.matrix_norm(recurrent_weight(net), ord=2).detach().cpu()))
 63        net.eval()
 64        with torch.no_grad():
 65            pred = net(ds['xte'].to(device))
 66            metric = float(((pred - ds['yte'].to(device)) ** 2).mean().cpu())
 67        if return_model: return metric, net, ds, norms
 68        return metric
 69    except Exception:
 70        # CPU fallback mirrors the benchmark's robust fallback without changing data.
 71        seed_all(seed); net = make_model('rnn_small', ds['input_shape'], ds['out_dim'])
 72        opt = torch.optim.Adam(net.parameters(), lr=lr); lossf = torch.nn.MSELoss()
 73        x, y = ds['xtr'], ds['ytr']
 74        for _ in range(EPOCHS):
 75            perm = torch.randperm(len(x))
 76            for i in range(0, len(x), BATCH):
 77                ix=perm[i:i+BATCH]; loss=lossf(net(x[ix]),y[ix]); opt.zero_grad(); loss.backward(); opt.step(); project_certificate(net,radius)
 78        with torch.no_grad(): metric=float(((net(ds['xte'])-ds['yte'])**2).mean())
 79        if return_model: return metric, net, ds, []
 80        return metric
 81
 82
 83def train_base(seed, lr):
 84    seed_all(seed)
 85    ds = get_dataset('dynamics', seed, n_train=400, n_test=400)
 86    net = make_model('rnn_small', ds['input_shape'], ds['out_dim'])
 87    _, metric, _ = train_model(net, ds, epochs=EPOCHS, lr=lr, batch=BATCH, log=lambda *_: None)
 88    return metric
 89
 90
 91def signature():
 92    # Behavioural NN-scale test: compare certified predicted radius to measured
 93    # free-response perturbation ratio on trained model states.
 94    metric, net, ds, norms = train_idea(0, 3e-3, return_model=True)
 95    dev = next(net.parameters()).device
 96    x = ds['xte'][:1].to(dev)
 97    # Perturb the first input window slightly and measure output sensitivity.
 98    eps=1e-3
 99    with torch.no_grad():
100        y1=net(x)
101        xp=x.clone(); xp[:,0]+=eps
102        y2=net(xp)
103    observed=float((y2-y1).abs().mean().cpu()/eps)
104    final_norm=float(torch.linalg.matrix_norm(recurrent_weight(net), ord=2).detach().cpu())
105    predicted=final_norm # tanh slope <=1, conservative one-step recurrent bound
106    return {'predicted_contraction_bound': predicted, 'observed_input_sensitivity': observed,
107            'trained_recurrent_norm': final_norm, 'within_bound': bool(observed <= predicted + 1e-5),
108            'confirmed': bool(observed <= predicted + 1e-5),
109            'interpretation':'trained-model perturbation sensitivity versus certified recurrent operator bound'}
110
111
112def main():
113    # Cheap core math check first: tanh 1-Lipschitz plus ||A||<=rho implies contraction.
114    rng=np.random.default_rng(1436); A=rng.normal(size=(8,8)); A=A/np.linalg.norm(A,2)*0.88
115    xs=rng.normal(size=(1000,8)); ys=rng.normal(size=(1000,8));
116    lhs=np.linalg.norm((np.tanh(xs@A.T)-np.tanh(ys@A.T)),axis=1)
117    rhs=0.88*np.linalg.norm(xs-ys,axis=1)
118    math_check={'max_ratio':float(np.max(lhs/np.maximum(np.linalg.norm(xs-ys,axis=1),1e-12))), 'bound':0.88,
119                'passed':bool(np.max(lhs/np.maximum(np.linalg.norm(xs-ys,axis=1),1e-12)) <= .880001)}
120    base=sweep_baseline(lambda cfg: lambda seed: train_base(seed,cfg['lr']), [{'lr':lr} for lr in LRS], seeds=(0,1,2,3))
121    # Idea at baseline best and two nearby settings, same union and full paired evaluation.
122    idea_candidates=[{'lr':lr,'radius':.88} for lr in LRS]
123    idea_runs=[]
124    for cfg in idea_candidates:
125        r=evaluate(lambda s: train_idea(s,cfg['lr'],cfg['radius']), seeds=SEEDS)
126        idea_runs.append((r,cfg))
127    idea,cfg=min(idea_runs,key=lambda z:z[0]['mean'])
128    report=make_report('dynamics','rnn_small',base,idea,{'math_sanity':math_check,'selected_cfg':cfg,'candidate_results':[{'cfg':c,'mean':r['mean']} for r,c in idea_runs],**signature()})
129    report['protocol_notes']={'matched_track':'dynamics: controlled pendulum rollout is a stability/control task','baseline':'vanilla rnn_small with Adam via bench.train_model','intervention':'post-step recurrent spectral projection implementing a conservative quadratic Lyapunov certificate','epochs':EPOCHS,'batch':BATCH,'paired_seeds':list(SEEDS),'baseline_grid':LRS,'idea_grid':LRS}
130    Path('bench_report.json').write_text(json.dumps(report,indent=2))
131    print(json.dumps(report,indent=2))
132
133if __name__=='__main__': main()