Compressing Value Predictions for Learning-Augmented Metrical Task Systems
Authors: Sizhe Li, Yecheng Li, Kun He
Organizations: School of Artificial Intelligence and Automation Huazhong University of Science and Technology Wuhan, Hubei 430074, China · School of Computer Science and Technology Huazhong University of Science and Technology Wuhan, Hubei 430074, China
Learning-augmented algorithms for metrical task systems (MTS) can exploit predictions of canonical dual values, but existing formulations typically require a prediction for every state. We study whether these predictions can be compressed to a small set of representative states while retaining their algorithmic value. We introduce landmark-compressed value predictions, in which the predictor reports predicted dual values only at m landmarks and the remaining values are reconstructed by a Lipschitz extension. Our algorithm achieves additive excess cost O(Tr(L)+∑tδt), where r(L) is the covering radius of the landmarks and δt measures prediction error up to additive shifts; local and value-dependent bounds refine this guarantee. For sparse landmark sets on unit-spaced finite lines, we prove a matching Ω(Trm) lower bound for every randomized algorithm using fixed landmarks, even with advance access to their entire exact absolute-value table. The prediction interface also matters: on two states with one landmark, exact absolute values permit horizon-independent excess, whereas exact relative values force worst-case expected excess linear in T. We give PAC guarantees for learning compressed prediction tables, with efficient empirical-risk minimization for fixed landmarks. Our results connect metric coverage, prediction interfaces, and learning guarantees for compressed predictions in online MTS.
Figures & tables
Setting
m/n
Full
Distortion
Random
Geom.
WFA
DC
K=3 , 1 min
24/120
1.2712
1.2695
2.2326
1.6518
1.5286
2.5541
K=3 , 15 min
24/120
1.1657
1.1659
1.5988
1.3081
1.4035
2.1838
K=4 , 1 min
42/210
1.1788
1.1786
3.4129
1.1895
1.6160
3.5168
K=4 , 15 min
42/210
1.1524
1.2043
1.5396
2.9478
1.7067
2.4071
K=5 , 1 min
50/252
1.0502
1.0499
3.1009
1.0706
1.7300
4.9765
K=5 , 15 min
50/252
1.3810
1.2737
2.2557
1.5288
1.9049
2.7607
Table 1: Mean daily ALG/OPT on 365 dates with the mean predictor and approximately 20% of predicted values retained. Bold marks row minima, including ties, without implying statistical significance. Additional comparisons are in Section G.1 .
Appendix figures & tables14 assets
Supplementary material from the paper’s appendix.
Appendix
Split
Dates
Days
Filtered trips
Initial fit
2023-01-01–2024-09-30
639
55,497,434
Validation
2024-10-01–2024-12-31
92
8,910,606
Final refit
2023-01-01–2024-12-31
731
64,408,040
Evaluation
2025-01-01–2025-12-31
365
36,453,843
Appendix
Table 2: Citi Bike data split. The final refit overlaps the two preceding rows.
Quantity
Localized
Switching
States / horizon / pair budget
9/12/2
9/12/2
Train / validation / test per seed
32/64/256
32/64/256
Preferred-center template μˉt
0.68+0.11sin(2πt/6)
0.50+0.30sin(2πt/6)
Episode / task Gaussian scales
0.045/0.035
0.045/0.035
Amplitude distribution
Unif[1.5,2.5]
Unif[4,7]
Per-state additive noise
Unif[0,0.025]
Unif[0,0.025]
Appendix
Table 3: Complete pilot configuration. Gaussian scales are standard deviations. Both scenarios use the same split sizes and landmark budget.
K
Resolution / contrast
Δ or contrast
95% block CI
3
1 min
-0.001747
[-0.003456, -0.000187]
3
15 min
+0.000169
[+0.000000, +0.000506]
3
1 min minus 15 min
-0.001916
[-0.003676, -0.000297]
4
1 min
-0.000142
[-0.000862, +0.000551]
4
15 min
+0.0518
[+0.0306, +0.0728]
4
1 min minus 15 min
-0.0520
[-0.0729, -0.0306]
Appendix
Table 4: Distortion minus Full with approximately 20% of predicted values retained, and its paired cross-resolution contrast. Each resolution uses its own daily OPT. All intervals here use circular seven-day blocks, 2,000 replicates, seed 20260922.
Setting
Comparison
Difference
95% block CI
K=3 , 15 min
Distortion - Random
-0.43294
[-0.4845, -0.3891]
K=3 , 15 min
Distortion - Geom.
-0.14221
[-0.2242, -0.0664]
K=4 , 15 min
Distortion - Random
-0.33533
[-0.3843, -0.2904]
K=4 , 15 min
Distortion - Geom.
-1.74355
[-1.8554, -1.6376]
K=5 , 15 min
Distortion - Random
-0.98201
[-1.0892, -0.8776]
K=5 , 15 min
Distortion - Geom.
-0.25517
[-0.3431, -0.1614]
Appendix
Table 5: Paired selector differences at approximately 20%. Negative differences favor Distortion. Intervals use 2,000 seven-day block replicates (seed 20260919) and are unadjusted for multiple comparisons. Distortion–Full intervals are in Table 4 .
Setting
Method
ALG/OPT
η /OPT
Recon.
K=3 , 15 min
Full
1.1657
7.6815
0.0000
K=3 , 15 min
Distortion
1.1659
9.4318
0.8925
K=4 , 15 min
Full
1.1524
9.7615
0.0000
K=4 , 15 min
Distortion
1.2043
18.2262
1.4162
K=5 , 15 min
Full
1.3810
15.5573
0.0000
K=5 , 15 min
Distortion
1.2737
39.5873
1.6323
Appendix
Table 6: Mean-predictor diagnostics for Full and approximately 20% Distortion. Recon. is the per-slot reconstruction span relative to predicted Full values. The supplementary CSV retains all four methods and their ordinary date-bootstrap marginal intervals.
Predictor
Full
95% block CI
RMSE
Error span
η /OPT
Static
1.1520
[1.1202, 1.1863]
1.0403
4.3440
12.4987
Mean
1.1524
[1.1214, 1.1865]
0.7726
2.9219
9.7615
MLP
1.1464
[1.1207, 1.1736]
0.7856
3.2413
15.5222
GRU
1.1378
[1.1139, 1.1632]
0.7649
3.0593
14.5484
Appendix
Table 7: Full-predictor costs and value errors on the 365 evaluation dates. RMSE uses centered exact values; value-error span and Bellman residual are distinct diagnostics.
Predictor
Method
ALG/OPT
95% block CI
Ret.
Recon.
Static
Distortion
1.1877
[1.1576, 1.2201]
93.57%
1.5840
Static
Random
1.7223
[1.6565, 1.7925]
-2.81%
3.9430
Static
Geom.
2.6758
[2.5404, 2.8136]
-174.69%
3.2623
Mean
Distortion
1.2043
[1.1826, 1.2259]
90.65%
1.4162
Mean
Random
1.5396
[1.4922, 1.5905]
30.15%
3.9819
Mean
Geom.
2.9478
[2.8428, 3.0563]
-223.90%
3.0379
Appendix
Table 8: Temporal-family compression retaining m=42 of 210 predicted values. Neural results average the crossed training and landmark seeds within each date. Bold marks the lowest ALG/OPT within each predictor, without implying statistical significance.
Comparison
Difference
95% block CI
GRU Full - Mean Full
-0.01463
[-0.0446, +0.0127]
GRU Full - MLP Full
-0.00860
[-0.0210, +0.0034]
GRU Full - Static Full
-0.01417
[-0.0442, +0.0134]
MLP Full - Mean Full
-0.00604
[-0.0328, +0.0182]
Static Full - Mean Full
-0.00046
[-0.0019, +0.0009]
Static: Distortion 20% - Full
+0.03569
[+0.0281, +0.0436]
Appendix
Table 9: Paired temporal-family comparisons. Intervals use seven-day block resampling and condition on the fitted data and seeds.
Setting
Oracle Distortion [95% CI]
Predicted minus oracle [95% CI]
K=3 , 1 min
1.0017 [1.0013, 1.0022]
+0.2678 [+0.2524, +0.2844]
K=3 , 15 min
1.0016 [1.0007, 1.0026]
+0.1643 [+0.1404, +0.1889]
K=4 , 1 min
1.0015 [1.0009, 1.0022]
+0.1771 [+0.1627, +0.1939]
K=4 , 15 min
1.0077 [1.0050, 1.0108]
+0.1966 [+0.1760, +0.2191]
K=5 , 1 min
1.0005 [1.0001, 1.0011]
+0.0494 [+0.0420, +0.0572]
K=5 , 15 min
1.0030 [1.0014, 1.0050]
+0.2707 [+0.2307, +0.3187]
Appendix
Table 10: Frozen-landmark exact-value diagnostic at approximately 20%. Oracle Full equals OPT in every setting. Intervals use seven-day blocks. The last column replaces inputs at fixed landmarks; it is not an independent causal component of total loss.
Minutes
Changed
Improved
Worsened
∑ΔQ/OPT [95% CI]
1 min
0.010
0.004
0.002
-0.000147 [-0.000493, +0.000110]
15 min
0.992
0.336
0.348
-0.0832 [-0.1311, -0.0360]
Appendix
Table 11: K=5 actions compared at the same states visited by predicted Full. Counts are daily averages; the final column averages the daily normalized sum of exact-continuation action differences. This is not the cost difference between the two policies' actual trajectories.
Setting
eˉ
S0/OPT
Ror
1+η/OPT
1+Badj/OPT
1+Bact/OPT
K=3 , 1 min
0.1848
1.450
1.0017
2.043
3.900
2.403
K=3 , 15 min
0.7715
8.138
1.0016
5.207
17.238
9.099
K=4 , 1 min
0.1423
3.506
1.0015
3.230
8.010
4.408
K=4 , 15 min
1.3849
19.542
1.0077
16.962
40.004
20.458
K=5 , 1 min
0.1725
9.965
1.0005
6.581
20.929
10.815
K=5 , 15 min
1.6489
41.135
1.0030
35.985
82.980
41.838
Appendix
Table 12: Exact-value distortion and certificates for Distortion at approximately 20%. Normalize within each date before averaging. The final three columns are cost-ratio upper bounds, not attained costs; Section F.7 defines S0,Badj,Bact .
Setting
365-day Distortion
355-day Distortion
K=3 , 1 min
1.2695
1.2707
K=3 , 15 min
1.1659
1.1688
K=4 , 1 min
1.1786
1.1797
K=4 , 15 min
1.2043
1.2054
K=5 , 1 min
1.0499
1.0494
K=5 , 15 min
1.2737
1.2743
Appendix
Table 13: Mean daily ALG/OPT at approximately 20% after excluding the first ten 2025 dates. All eight settings use the same fitted models and landmarks as their full-year evaluations.
Method
Localized
Switching
Uniform random pairs (exact average)
0.40154±0.01142
0.43569±0.00668
Geometric pair
0.17838±0.01720
0.39766±0.01932
Learned distortion pair
0.04810±0.00666
0.13927±0.01661
Learned validation pair
0.04810±0.00666
0.13927±0.01661
Learned singleton
0.04810±0.00666
0.41436±0.00850
Full-state fixed table
0.04810±0.00666
0.04031±0.00882
Appendix
Table 14: Test total episode excess ALG−OPT : mean ± sample standard deviation of the three seed-level means (not confidence intervals). Oracle full-state excess is below 10−15 in magnitude and displayed as zero. Bold marks the lowest non-oracle mean in each column, including ties, without implying statistical significance.
Localized
Switching
Method
Cκ
Cloc
Cκ
Cloc
Geometric pair
3.05480
1.72344
3.94197
4.21647
Learned distortion pair
1.15931
0.60406
2.13124
1.79679
Learned validation pair
1.51201
0.49766
2.13124
1.79679
Learned singleton
1.30334
0.28874
4.05037
3.42253
Full-state fixed table
0.94929
0.94929
0.98307
0.98307
Appendix
Table 15: Mean offline certificates over the three seed-level test means. Observed excess and seed standard deviations are in Table 14 ; Cκ and Cloc are defined in ( 59 ).
Learning-augmented algorithms have received significant attention in recent years, particularly in the context of online optimization. Motivated by the high computational cost of generating predictions, a growing line of work studies the tradeoff between performance guarantees and the number of predictions used in learning-augmented algorithms for problems such as caching and metrical task systems. In this paper, we extend this line of research to online metric matching by developing parsimonious learning-augmented algorithms and establishing lower bounds on their performance. Our approach extends the Follow-the-Prediction framework to the parsimonious setting by filling in a virtual prediction in the absence of an actual prediction, using an online metric matching algorithm that maintains good intermediate matchings throughout its execution. We complement our theoretical results with an empirical evaluation, demonstrating the practical effectiveness of our approach.
Yongho Shin, Phanu Vajanopath
Institute of Computer Science, University of Wrocław, Wrocław, Poland.
We present learning-augmented algorithms for two general classes of online minimization problems: metrical task systems and laminar set cover. Both algorithms achieve improved theoretical guarantees using machine-learned predictions of an optimal solution to the dual linear program. Unlike optimal primal solutions, which can change drastically under tiny instance perturbations, these dual solutions are much more stable, which ensures the existence of good (and learnable) predictions for families of similar instances. While previous work has used dual predictions in offline settings and for online maximization problems, our algorithms are, to the best of our knowledge, the first demonstration that such dual predictions can be effective for online minimization. Our theoretical results are complemented by experiments on the k-server problem and the parking permit problem.
Christian Coester, Alexa Tudose, Alexander Turoczy
The field of learning-augmented algorithms has demonstrated that machine-learned predictions can bypass worst-case lower bounds across a wide range of problems. So far, however, the focus has been almost exclusively on polynomial-time algorithms, where predictions improve competitive ratios, approximation guarantees, or running times. In this paper, we raise the question of whether predictions can push the frontier of exact exponential-time algorithms for NP-hard problems. We answer this question affirmatively by proposing a general approach that augments an entire family of state-of-the-art exact algorithms for a variety of subset selection problems. We show that a noisy predictor that is only marginally better than random guessing suffices to provably reduce the search space, and that the resulting runtime speedup scales smoothly with the prediction quality. Importantly, our algorithms require only pairwise independence of predictions or, alternatively, do not require the knowledge of the predictor's accuracy - both strictly weaker and more realistic settings than typically assumed.