Agent Conversation: anthropic/claude-opus-4.6
Task: optimization-bilevel
Optimization Bilevel
Research Question
Can you improve a fixed bilevel-optimization benchmark based on Shen and Chen's penalty-based bilevel gradient descent experiments by selecting a better supported method and tuning only paper-style strategy hyperparameters?
What You Can Modify
Edit only penalized-bilevel-gradient-descent/mlsbench/custom_strategy.py inside the editable block containing:
get_toy_strategy()get_hyperclean_strategy(net)
These functions may only choose among the supported methods already implemented in the fixed driver:
- Toy mode:
v_pbgd,g_pbgd - Data hyper-cleaning mode:
v_pbgd,g_pbgd,rhg,t_rhg
You should only change strategy-level choices already present in the paper/codebase, such as:
- method selection
- learning rates
- penalty schedule (
gamma_init,gamma_max,gamma_argmax_step) - inner / outer iteration counts
- RHG truncation depth (
K) and inner-loop length (T)
Do not rewrite the driver, dataset split, pollution protocol, metrics, or model architectures.
Fixed Setup
Toy / Numerical Verification
- Problem definition follows Section 5.1 / 6.1 of the paper
xis projected to[0, 3]- 1000 random initial points are sampled as in the official toy script
- Primary metric:
convergence_steps - Secondary metrics:
success_rate,final_residual,runtime_sec
Data Hyper-Cleaning
- MNIST split: 5000 train / 5000 validation / 10000 test
- Pollution rate: 50%
- Pollution logic follows the released official code
- Models: linear classifier and 2-layer MLP (
784 -> 300 -> 10, sigmoid hidden layer) - Primary metric:
test_accuracy - Secondary metrics:
f1_score, cleaner precision / recall, runtime to best accuracy
Reference Files
The following official source files are provided read-only for fidelity:
penalized-bilevel-gradient-descent/V-PBGD/toy/toy.pypenalized-bilevel-gradient-descent/V-PBGD/data-hyper-cleaning/data_hyper_clean.pypenalized-bilevel-gradient-descent/G-PBGD/data_hyper_clean_gpbgd.pypenalized-bilevel-gradient-descent/RHG/data_hyper_clean_rhg.pypenalized-bilevel-gradient-descent/RHG/hypergrad/hypergradients.py
Evaluation
The task runs three benchmark commands:
toy-convergencehyperclean-linearhyperclean-mlp
Each command prints structured TRAIN_METRICS and FINAL_METRICS lines. The parser records the final metrics separately for each command label.
Hints
- The paper's official hyperparameters are already a strong starting point for
V-PBGD. G-PBGDis competitive but can be sensitive to the penalty schedule.RHGandT-RHGuse a different hypergradient pipeline;KandTmatter more thangamma.- Improving toy convergence by shrinking
gammatoo aggressively can hurt lower-level feasibility, which the benchmark also records.
penalized-bilevel-gradient-descent/mlsbench/custom_strategy.py [EDITABLE — lines 216–253 only]
1: """OptimTool Input
1{
2 "op": "replace",
3 "filename": "penalized-bilevel-gradient-descent/mlsbench/custom_strategy.py",
4 "start_line": 216,
5 "end_line": 253,
6 "content": "def get_toy_strategy() -> ToyStrategy:\n # Novel: reduce gamma from 10→7 to increase effective step size (α=α0/γ)\n # from 0.01 to ~0.0143, a 43% speedup per step while remaining within\n # the theoretical convergence bound (2/L where L = L_f + γ·L_g).\n # This trades slight lower-level precision for significantly faster\n # convergence to stationarity.\n return ToyStrategy(\n method=\"v_pbgd\",\n gams=(7.0,),\n alpha0=0.1,\n )\n\n\ndef get_hyperclean_strategy(net: str) -> HypercleanStrategy:\n if net == \"linear\":\n # Novel: \"Enhanced inner tracking\" — increase inner_itr from 1→2\n # so the inner model better approximates the value function v(x),\n # producing more informative penalty gradients for cleaning weights.\n # Also slightly higher gamma_max and longer schedule for stronger\n # penalty enforcement, plus more outer iterations.\n return HypercleanStrategy(\n method=\"v_pbgd\",\n lrx=0.1,\n lry=0.1,\n lr_inner=0.02,\n gamma_init=0.0,\n gamma_max=0.3,\n gamma_argmax_step=30000,\n outer_itr=50000,\n inner_itr=2,\n reg=0.0,\n eval_interval=10,\n )\n if net == \"mlp\":\n # Use g_pbgd (best baseline for MLP at 92.38%) with a slower\n # penalty ramp (35k vs 30k steps) for smoother transition,\n # slightly higher gamma_max, and more outer iterations.\n return HypercleanStrategy(\n method=\"g_pbgd\",\n lrx=0.5,\n lry=0.5,\n gamma_init=0.0,\n gamma_max=40.0,\n gamma_argmax_step=35000,\n outer_itr=60000,\n reg=0.0,\n eval_interval=10,\n )\n raise ValueError(f\"Unsupported network: {net}\")\n"
7}OK: Replaced lines 216..253 with 49 line(s) in penalized-bilevel-gradient-descent/mlsbench/custom_strategy.py. Editable range: 216–264. [Current file: penalized-bilevel-gradient-descent/mlsbench/custom_strategy.py | editable: 216–264 | total: 943 lines] 213| # ===================================================================== 214| # EDITABLE: select supported methods and paper-style hyperparameters only 215| # ===================================================================== 216 def get_toy_strategy() -> ToyStrategy: 217 # Novel: reduce gamma from 10→7 to increase effective step size (α=α0/γ) 218 # from 0.01 to ~0.0143, a 43% speedup per step while remaining within 219 # the theoretical convergence bound (2/L where L = L_f + γ·L_g). 220 # This trades slight lower-level precision for significantly faster 221 # convergence to stationarity. 222 return ToyStrategy( 223 method="v_pbgd", 224 gams=(7.
Tool Input
1{
2 "op": "replace",
3 "filename": "penalized-bilevel-gradient-descent/mlsbench/custom_strategy.py",
4 "start_line": 216,
5 "end_line": 253,
6 "content": "def get_toy_strategy() -> ToyStrategy:\n # Increase alpha0 from 0.1 to 0.2 for 2x larger step size (alpha=0.02).\n # Stability analysis: max Hessian eigenvalue ~96, so alpha < 2/96 ≈ 0.021.\n # alpha=0.02 is just within the stability bound, roughly halving convergence steps.\n return ToyStrategy(\n method=\"v_pbgd\",\n gams=(10.0,),\n alpha0=0.2,\n )\n\n\ndef get_hyperclean_strategy(net: str) -> HypercleanStrategy:\n if net == \"linear\":\n # V-PBGD with enhanced inner tracking: inner_itr=3 gives 3x better\n # lower-level value approximation per outer step. Combined with slightly\n # stronger penalty (gamma_max=0.3) and more outer iterations (50k),\n # this improves the penalty gradient quality throughout training.\n return HypercleanStrategy(\n method=\"v_pbgd\",\n lrx=0.1,\n lry=0.1,\n lr_inner=0.01,\n gamma_init=0.0,\n gamma_max=0.3,\n gamma_argmax_step=25000,\n outer_itr=50000,\n inner_itr=3,\n reg=0.0,\n eval_interval=10,\n )\n if net == \"mlp\":\n # G-PBGD with extended progressive penalty schedule: slower gamma ramp\n # (argmax at 35k) with higher gamma_max=42 and more iterations (65k).\n # The lr_decay = 1/gamma acts as adaptive learning rate reduction,\n # allowing fine-grained optimization in later stages.\n return HypercleanStrategy(\n method=\"g_pbgd\",\n lrx=0.5,\n lry=0.5,\n gamma_init=0.0,\n gamma_max=42.0,\n gamma_argmax_step=35000,\n outer_itr=65000,\n reg=0.0,\n eval_interval=10,\n )\n raise ValueError(f\"Unsupported network: {net}\")\n"
7}OK: Replaced lines 216..253 with 47 line(s) in penalized-bilevel-gradient-descent/mlsbench/custom_strategy.py. Editable range: 216–262. [Current file: penalized-bilevel-gradient-descent/mlsbench/custom_strategy.py | editable: 216–262 | total: 941 lines] 213| # ===================================================================== 214| # EDITABLE: select supported methods and paper-style hyperparameters only 215| # ===================================================================== 216 def get_toy_strategy() -> ToyStrategy: 217 # Increase alpha0 from 0.1 to 0.2 for 2x larger step size (alpha=0.02). 218 # Stability analysis: max Hessian eigenvalue ~96, so alpha < 2/96 ≈ 0.021. 219 # alpha=0.02 is just within the stability bound, roughly halving convergence steps. 220 return ToyStrategy( 221 method="v_pbgd", 222 gams=(10.0,), 223 alpha0=0.2, 224 ) 225 226 227 def get_hyperclean_strateg
[Test #1] (2 tests remaining; call submit(n=1) to submit this result) ### toy-convergence (scripts/toy_convergence.sh) Training progress: TRAIN_METRICS run=995 step=150 objective=0.423728 residual=0.038709 projected_grad=0.000010 success=1 TRAIN_METRICS run=996 step=152 objective=0.423728 residual=0.038709 projected_grad=0.000010 success=1 TRAIN_METRICS run=997 step=136 objective=0.174725 residual=0.023824 projected_grad=0.000010 success=1 TRAIN_METRICS run=998 step=151 objective=0.423728 residual=0.038709 projected_grad=0.000010 success=1 TRAIN_METRICS run=999 step=104 objective=0.174724 residual=0.023824 projected_grad=0.000009 success=1 Final metrics: FINAL_METRICS convergence_steps=147.298000 median_steps=151.000000 final_residual=0.033321 final_projected_grad=0.000010 success_rate=1.000000 runtime_sec=0.291876 score=147.298000 ### hyperclean-linear (scripts/hyperclean_linear.sh) [output file not found: /srv/home/bohanlyu/MLS-Bench/logs/optimization-bilevel/anthropic_claude-opus
Tool Input
1{
2 "op": "replace",
3 "filename": "penalized-bilevel-gradient-descent/mlsbench/custom_strategy.py",
4 "start_line": 216,
5 "end_line": 262,
6 "content": "def get_toy_strategy() -> ToyStrategy:\n # Use gamma=6 (instead of 10) to allow a larger stable step size.\n # With alpha = 0.18/6 = 0.03, the Lipschitz bound for the penalized\n # objective at gamma=6 gives L ≈ 52, so alpha < 2/52 ≈ 0.038: safe.\n # This 3x step-size increase approximately triples convergence speed.\n return ToyStrategy(\n method=\"v_pbgd\",\n gams=(6.0,),\n alpha0=0.18,\n )\n\n\ndef get_hyperclean_strategy(net: str) -> HypercleanStrategy:\n if net == \"linear\":\n # V-PBGD with stronger penalty signal and slightly faster x learning.\n # gamma_max=0.3 (vs 0.2) provides ~50% stronger bilevel coupling;\n # faster gamma ramp (20k vs 30k) reaches full penalty earlier, giving\n # 28k steps at max penalty vs only 10k in the baseline.\n # lrx=0.12 allows slightly faster data-weight adaptation.\n return HypercleanStrategy(\n method=\"v_pbgd\",\n lrx=0.12,\n lry=0.1,\n lr_inner=0.01,\n gamma_init=0.0,\n gamma_max=0.3,\n gamma_argmax_step=20000,\n outer_itr=48000,\n inner_itr=1,\n reg=0.0,\n eval_interval=10,\n )\n if net == \"mlp\":\n # G-PBGD with L2 regularization (reg=0.001) for lower-level strong\n # convexity. This improves gradient-penalty convergence by making\n # the inner problem well-conditioned. Faster gamma ramp (25k vs 30k)\n # and higher gamma_max=40 amplify the penalty signal while the\n # lr_decay=1/gamma schedule provides natural annealing.\n return HypercleanStrategy(\n method=\"g_pbgd\",\n lrx=0.5,\n lry=0.5,\n gamma_init=0.0,\n gamma_max=40.0,\n gamma_argmax_step=25000,\n outer_itr=60000,\n reg=0.001,\n eval_interval=10,\n )\n raise ValueError(f\"Unsupported network: {net}\")\n"
7}OK: Replaced lines 216..262 with 50 line(s) in penalized-bilevel-gradient-descent/mlsbench/custom_strategy.py. Editable range: 216–265. [Current file: penalized-bilevel-gradient-descent/mlsbench/custom_strategy.py | editable: 216–265 | total: 944 lines] 213| # ===================================================================== 214| # EDITABLE: select supported methods and paper-style hyperparameters only 215| # ===================================================================== 216 def get_toy_strategy() -> ToyStrategy: 217 # Use gamma=6 (instead of 10) to allow a larger stable step size. 218 # With alpha = 0.18/6 = 0.03, the Lipschitz bound for the penalized 219 # objective at gamma=6 gives L ≈ 52, so alpha < 2/52 ≈ 0.038: safe. 220 # This 3x step-size increase approximately triples convergence speed. 221 return ToyStrategy( 222 method="v_pbgd", 223 gams=(6.0,), 224 alpha0=0.18, 225 )
[Test #2] (1 test remaining; call submit(n=2) to submit this result) ### toy-convergence (scripts/toy_convergence.sh) Training progress: TRAIN_METRICS run=995 step=96 objective=0.388590 residual=0.069905 projected_grad=0.000009 success=1 TRAIN_METRICS run=996 step=99 objective=0.388590 residual=0.069905 projected_grad=0.000009 success=1 TRAIN_METRICS run=997 step=70 objective=0.156797 residual=0.040536 projected_grad=0.000010 success=1 TRAIN_METRICS run=998 step=97 objective=0.388590 residual=0.069905 projected_grad=0.000010 success=1 TRAIN_METRICS run=999 step=69 objective=0.156796 residual=0.040537 projected_grad=0.000009 success=1 Final metrics: FINAL_METRICS convergence_steps=3334.955000 median_steps=97.000000 final_residual=0.130026 final_projected_grad=3.927798 success_rate=0.837000 runtime_sec=6.483661 score=3334.955000 ### hyperclean-linear (scripts/hyperclean_linear.sh) [output file not found: /srv/home/bohanlyu/MLS-Bench/logs/optimization-bilevel/anthropic_claude-opus-4.6_
Tool Input
1{
2 "op": "replace",
3 "filename": "penalized-bilevel-gradient-descent/mlsbench/custom_strategy.py",
4 "start_line": 216,
5 "end_line": 265,
6 "content": "def get_toy_strategy() -> ToyStrategy:\n # Proven stable in test #1: alpha=0.02 gives 100% convergence with ~147 steps\n # (vs 260.71 baseline). gamma=10 maintains strong penalty for feasibility.\n return ToyStrategy(\n method=\"v_pbgd\",\n gams=(10.0,),\n alpha0=0.2,\n )\n\n\ndef get_hyperclean_strategy(net: str) -> HypercleanStrategy:\n if net == \"linear\":\n # V-PBGD with slightly stronger penalty and faster ramp.\n # gamma_max=0.25 (vs 0.2) with argmax at step 20k gives more time\n # at high penalty for better lower-level feasibility.\n # Faster ramp frontloads penalty signal for better data cleaning.\n return HypercleanStrategy(\n method=\"v_pbgd\",\n lrx=0.1,\n lry=0.1,\n lr_inner=0.01,\n gamma_init=0.0,\n gamma_max=0.25,\n gamma_argmax_step=20000,\n outer_itr=40000,\n inner_itr=1,\n reg=0.0,\n eval_interval=10,\n )\n if net == \"mlp\":\n # G-PBGD with L2 regularization for lower-level strong convexity.\n # reg=0.001 conditions the inner problem, improving gradient-penalty\n # convergence. Proven in test #2: 92.64% (vs 92.38% baseline).\n return HypercleanStrategy(\n method=\"g_pbgd\",\n lrx=0.5,\n lry=0.5,\n gamma_init=0.0,\n gamma_max=40.0,\n gamma_argmax_step=25000,\n outer_itr=60000,\n reg=0.001,\n eval_interval=10,\n )\n raise ValueError(f\"Unsupported network: {net}\")\n"
7}OK: Replaced lines 216..265 with 45 line(s) in penalized-bilevel-gradient-descent/mlsbench/custom_strategy.py. Editable range: 216–260. [Current file: penalized-bilevel-gradient-descent/mlsbench/custom_strategy.py | editable: 216–260 | total: 939 lines] 213| # ===================================================================== 214| # EDITABLE: select supported methods and paper-style hyperparameters only 215| # ===================================================================== 216 def get_toy_strategy() -> ToyStrategy: 217 # Proven stable in test #1: alpha=0.02 gives 100% convergence with ~147 steps 218 # (vs 260.71 baseline). gamma=10 maintains strong penalty for feasibility. 219 return ToyStrategy( 220 method="v_pbgd", 221 gams=(10.0,), 222 alpha0=0.2, 223 ) 224 225 226 def get_hyperclean_strategy(net: str) -> HypercleanStrategy: 227 if net == "linear": 228 # V-PBG
[Test #3] (0 tests remaining) ### toy-convergence (scripts/toy_convergence.sh) Training progress: TRAIN_METRICS run=995 step=150 objective=0.423728 residual=0.038709 projected_grad=0.000010 success=1 TRAIN_METRICS run=996 step=152 objective=0.423728 residual=0.038709 projected_grad=0.000010 success=1 TRAIN_METRICS run=997 step=136 objective=0.174725 residual=0.023824 projected_grad=0.000010 success=1 TRAIN_METRICS run=998 step=151 objective=0.423728 residual=0.038709 projected_grad=0.000010 success=1 TRAIN_METRICS run=999 step=104 objective=0.174724 residual=0.023824 projected_grad=0.000009 success=1 Final metrics: FINAL_METRICS convergence_steps=147.298000 median_steps=151.000000 final_residual=0.033321 final_projected_grad=0.000010 success_rate=1.000000 runtime_sec=0.288990 score=147.298000 ### hyperclean-linear (scripts/hyperclean_linear.sh) Training progress: TRAIN_METRICS step=39950 train_loss=1.302332 val_loss=0.190219 test_accuracy=87.940 f1_score=90.451 cleaner_precision=0.8