Rethinking Prediction Horizons: Decoupling Model Queries from State Updates in Few-Step MeanFlow
Organizations: Beijing QBoson Quantum Technology Co., Ltd. · University of Sydney
Abstract
MeanFlow predicts interval-average velocities, but conventional few-step sampling ties the interval queried from the model to the duration of the state update. We separate these two quantities at inference, fixing the model, update grid, and number of queries while varying the prediction horizon. Our central finding is that the horizon response depends on both query position and the states entering that query. Across seven independently trained CIFAR-10 checkpoints at classifier-free guidance (CFG) scale 2, a longer horizon worsens FID at early steps but improves it at the midpoint. To probe whether query time alone determines this response, we fix the midpoint query and current/subsequent guidance while changing only earlier CFG. In held-out factorial outcomes on five previously studied checkpoints, the mean midpoint horizon benefit increases from 0.109 to 1.308 FID, indicating sensitivity to the incoming-state distribution. A frozen four-query rule reduces mean CIFAR-10 FID by 2.023 without retraining or extra queries, including gains on five checkpoints trained after rule selection. A milder rule also improves mean FID by 1.041 on a stronger frozen grid, with fixed-rule FID gains on the evaluated public ImageNet-256 and AFHQ checkpoints. However, matched-budget calibration favors query-start shifting in historical CIFAR tests, and the tested Horizon allocation adds no FID benefit beyond Grid+Start on two public ImageNet models. Thus, prediction horizon is a distinct, position- and state-sensitive inference control, but not a universally preferred one.
Figures & tables
| State grid | Checkpoints | FID gain [95% interval] | FID/KID wins |
|---|---|---|---|
| Uniform | Prospective five | 1.906 | 5/5; 5/5 |
| Uniform | All seven | 2.023 | 7/7; 7/7 |
| Frozen stronger grid | Same five | 1.015 | 5/5; 5/5 |
| Frozen stronger grid | All seven | 1.041 | 7/7; 7/7 |
| Rule | FID | KID | DINO | DINO P | DINO R |
|---|---|---|---|---|---|
| A: Calibrated rules, CFG 1.5; 50k generated / 50k real | |||||
| Local | 10.272 | 5.782 | – | – | – |
| Calibrated Horizon | 8.878 | 4.831 | – | – | – |
| Calibrated Start | 8.311 | 3.538 | – | – | – |
| B: Identical saved pixels, CFG 1.5; 10k generated / 10k real | |||||
| Local | 14.212 | 5.811 | 150.730 | 0.7171 | 0.3617 |
| Model | Grid+Start | Grid+Start+Horizon | Restored |
|---|---|---|---|
| B/2 | 7.2227 | 7.2498 | 7.2743 |
| XL/2 | 4.7969 | 4.8327 | 4.8327 |
| Seed | NFE | Local | Fixed H | Cal. H | Cal. Start | Mixed (choice) |
|---|---|---|---|---|---|---|
| 700081 | 2 | 15.122 | n/a | 15.122 | 15.122 | 15.122 (Local) |
| 700081 | 4 | 14.123 | 13.670 | 12.632 | 12.844 | 12.632 (H) |
| 700081 | 8 | 13.061 | 13.009 | 12.771 | 12.680 | 12.680 (Start) |
| 700087 | 2 | 15.075 | n/a | 15.075 | 15.075 | 15.075 (Local) |
| 700087 | 4 | 14.326 | 13.848 | 12.648 | 12.912 | 12.648 (H) |
| 700087 | 8 | 13.288 | 13.234 | 12.997 | 12.989 | 12.989 (Start) |
Appendix figures & tables28 assets
Supplementary material from the paper’s appendix.
Appendix
| Cohort | Checkpoints | Role and replication unit |
|---|---|---|
| Original CIFAR | 300007, 300017 | Two training units; three paired 50k repeats each |
| Prospective extension | 700001, 700027, 700057, 700067, 700079 | Five new training units; one paired 50k repeat each |
| Later blind study | 700081, 700087 | Two separate new units; NFE 2/4/8, two 10k confirmations per selected setting |
| Historical CIFAR transfer | Seeds 42, 123, 2027 in each of three pairing recipes | Reused historical models; separate transfer evidence |
| Public ImageNet | MeanFlow-B/2, MeanFlow-XL/2, AlphaFlow-B/2 | Three public checkpoints, not common-architecture seed replication |
| AFHQv2 | Two corrected and two QMAC-trained checkpoints | Four held-out checkpoints in two training families |
| State grid | Checkpoints | Local FID | Horizon FID | Gain [95% interval] | FID/KID wins |
|---|---|---|---|---|---|
| Uniform | Prospective five | 12.168 | 10.262 | 1.906 | 5/5; 5/5 |
| Uniform | All seven | 12.241 | 10.218 | 2.023 | 7/7; 7/7 |
| Best of 84 | Same five | 11.197 | 10.182 | 1.015 | 5/5; 5/5 |
| Best of 84 | All seven | 11.236 | 10.195 | 1.041 | 7/7; 7/7 |
| Train seed | Uniform repeats | Cohort | Uniform-grid gain | Frozen-grid gain | ||
|---|---|---|---|---|---|---|
| FID | KID | FID | KID | |||
| 300007 | 3 | original | 2.3628 | 1.755 | 1.1835 | .794 |
| 300017 | 3 | original | 2.2657 | 1.629 | 1.0269 | .674 |
| 700001 | 1 | prospective | 1.8780 | 1.374 | .9956 | .665 |
| 700027 | 1 | prospective | 1.7943 | 1.317 | .9203 | .574 |
| 700057 | 1 | prospective | 1.8535 | 1.354 | .9859 | .657 |
| State time | Queried horizons | Mean FID gains | Positive checkpoints |
|---|---|---|---|
| 0 | .25,.375,.50,.625,.75,.875,1 | .000,-.798,-2.220,-3.855,-5.639,-7.531,-9.732 | 0/7,0/7,0/7,0/7,0/7,0/7,0/7 |
| .25 | .25,.375,.50,.625,.75 | .000,-.031,-.092,-.280,-.837 | 0/7,2/7,1/7,1/7,0/7 |
| .50 | .25,.30,.35,.40,.45,.50 | .000,+.489,+.970,+1.414,+1.774,+2.010 | 0/7,7/7,7/7,7/7,7/7,7/7 |
| Sampler | Velocity queries | CIFAR ms (batch 128) | ImageNet ms (batch 16) |
|---|---|---|---|
| Local | 4 | 342.09 | 212.71 |
| Horizon | 4 | 344.93 | 212.54 |
| Local | 5 | 431.59 | 226.56 |
| Continuous lookahead | 5 | 435.29 | 225.35 |
| Local | 6 | 519.91 | 238.95 |
| Rule | FID | KID | P | R | ||
|---|---|---|---|---|---|---|
| Local | .500 | .250000 | 14.204 | 5.811 | .746 | .419 |
| State grid | .800 | .100000 | 12.908 | 4.764 | .744 | .438 |
| Start | .575 | .250000 | 12.380 | 3.506 | .672 | .506 |
| Horizon | .500 | .489583 | 12.902 | 4.901 | .649 | .545 |
| Joint | .400 | .500000 | 12.216 | 3.335 | .737 | .465 |
| Rule | Dataset | Units | FID wins | FID gain | KID gain |
|---|---|---|---|---|---|
| Tuned | CIFAR-10 | 7 | 7/7 | 2.023 | 0.001456 |
| Tuned | AFHQv2-256 | 4 | 4/4 | 0.212 | mixed |
| CIFAR, three recipes | 9 | 9/9 | 0.490 | 0.000397 | |
| ImageNet-256 | 3 | 3/3 | 0.111 | – | |
| AFHQv2-256 | 4 | 4/4 | 0.194 | .000098 |
| Checkpoint | Repeats | Local FID | Horizon FID | Gain | Relative |
|---|---|---|---|---|---|
| MeanFlow-B/2 | 1 | 5.1859 | 5.0551 | .1308 | 2.52% |
| MeanFlow-XL/2 | 3 | 2.6300 | 2.5326 | .0974 | 3.70% |
| AlphaFlow-B/2 | 3 | 5.0633 | 4.9570 | .1063 | 2.10% |
| Checkpoint | Local | Horizon | Inherited Start |
|---|---|---|---|
| MeanFlow-B/2 | 5.13619 / 245.217 | 5.00426 / 242.393 | 5.63790 / 211.474 |
| MeanFlow-XL/2 | 2.61386 / 288.267 | 2.51254 / 286.031 | 2.87045 / 255.497 |
| AlphaFlow-B/2 | 4.95572 / 243.945 | 4.84760 / 241.635 | 5.55436 / 212.154 |
| Grid / external CFG | Model | Start | Horizon | Local | Start | Horizon |
|---|---|---|---|---|---|---|
| Narrow / 1 | B/2 | .5250 | .325 | 7.4992 / 190.41 | 7.2680 / 187.38 | 7.3439 / 187.21 |
| Narrow / 1 | XL/2 | .5500 | .325 | 5.0265 / 222.08 | 4.8885 / 211.31 | 4.9159 / 219.12 |
| Narrow / .8 | B/2 | .5000 | .250 | 7.5811 / 147.15 | 7.5811 / 147.15 | 7.5811 / 147.15 |
| Narrow / .8 | XL/2 | .5000 | .225 | 4.9491 / 175.21 | 4.9491 / 175.21 | 4.9421 / 176.38 |
| Range / 1 | B/2 | .5375 | .400 | 7.4987 / 191.03 | 7.2297 / 184.14 | 7.3075 / 183.24 |
| Range / 1 | XL/2 | .5375 | .400 | 5.0728 / 219.59 | 4.8566 / 214.59 | 4.9277 / 213.02 |
| Model | Local | Start | Horizon | Joint |
|---|---|---|---|---|
| B/2 | 7.5071 / 188.03 | 7.2339 / 182.83 | 7.3282 / 180.92 | 8.0472 / 166.11 |
| XL/2 | 5.0275 / 219.95 | 4.8304 / 214.39 | 4.8879 / 212.36 | 5.4654 / 197.56 |
| Model | Repeat | GS FID | GSH FID | Restored FID | Min. IS ratio | ||
|---|---|---|---|---|---|---|---|
| B/2 | 1 | 7.2216 | 7.2564 | 7.2808 | -0.0347 | +0.0244 | 0.9941 |
| B/2 | 2 | 7.2238 | 7.2433 | 7.2678 | -0.0195 | +0.0245 | 0.9956 |
| XL/2 | 1 | 4.8049 | 4.8307 | 4.8307 | -0.0258 | +0.0000 | 1.0000 |
| XL/2 | 2 | 4.7888 | 4.8347 | 4.8347 | -0.0459 | +0.0000 | 0.9949 |
| Contrast | FID | 95% interval | Lower | KID | 95% interval | Lower |
|---|---|---|---|---|---|---|
| Horizon – Local | -1.298 | 7/7 | -0.898 | 7/7 | ||
| Start – Local | -1.824 | 7/7 | -2.296 | 7/7 | ||
| Horizon – Start | +0.526 | 0/7 | +1.398 | 0/7 |
| Contrast | distance | 95% interval | Lower | P (pp) | R (pp) |
|---|---|---|---|---|---|
| Horizon – Local | -3.132 | 7/7 | -2.04 | +3.05 | |
| Start – Local | +14.690 | 0/7 | -3.50 | +0.33 | |
| Horizon – Start | -17.822 | 7/7 | +1.46 | +2.72 |
| Arm | Old FID | New FID | FID | 95% interval | Old KID | New KID | KID |
|---|---|---|---|---|---|---|---|
| Local | 14.204 | 14.212 | +.0074 | 5.8109 | 5.8106 | -.0003 | |
| Start | 12.380 | 12.388 | +.0078 | 3.5057 | 3.5144 | +.0087 | |
| Horizon | 12.902 | 12.914 | +.0121 | 4.9006 | 4.9125 | +.0119 |
| Cohort | Train seed | ||||
|---|---|---|---|---|---|
| Pilot | 300007 | 0.1992 | 1.5668 | 1.3676 | 1.3368 |
| Pilot | 300017 | 0.4131 | 1.6243 | 1.2112 | 1.1190 |
| Replication | 700001 | 0.1046 | 1.2689 | 1.1642 | 1.1723 |
| Replication | 700027 | 0.1701 | 1.2305 | 1.0604 | 1.1565 |
| Replication | 700057 | -0.1728 | 1.1677 | 1.3405 | 1.3043 |
| Replication | 700067 | 0.0941 | 1.2851 | 1.1910 | 1.1661 |
| FID | KID | |||
|---|---|---|---|---|
| Checkpoint | Local | Horizon | Local | Horizon |
| Local MAC s42 (dev.) | 16.7540 | 16.7410 | 10.5848 | 10.9653 |
| Paired recipe s300007 | 15.9024 | 16.0348 | 9.4296 | 9.9692 |
| Paired recipe s300017 | 15.7868 | 15.6920 | 9.3806 | 9.6567 |
| Panel | Existing training seeds | Repeats/model | Images |
|---|---|---|---|
| Projection | 300007, 300017 | 2 | 160,000 |
| Equal norm | 700001, 700027 | 1 | 100,000 |
| Signed dose | 700057, 700067 | 1 | 100,000 |
| Prefix | 700057, 700067 | 1 | 120,000 |
| Panel | Treatment / reference | FID gain | DINO gain |
|---|---|---|---|
| Projection | Residual / Local | +2.817 | +16.560 |
| Full / Projected | +0.850 | +10.077 | |
| Projected / Local | +0.745 | -5.899 | |
| Equal norm | Residual / scaled Full | +1.165 | +9.728 |
| Residual / Random | +2.352 | +14.456 | |
| Signed | / | +7.158 | +78.923 |
| Panel | Contrast / gate | Units | Min. FID | Min. DINO | FID margin |
|---|---|---|---|---|---|
| Projection | Full / Local (prereq.) | 4 pairs | +1.5006 | +2.7743 | – |
| Residual / Local | 4 pairs | +2.6896 | +15.0465 | +2.6608 | |
| Full / Projected | 4 pairs | +0.6452 | +8.9053 | +0.5967 | |
| Equal norm | Residual / Local | 2 models | +2.3228 | +15.4099 | +2.2728 |
| Residual / scaled Full | 2 models | +0.9694 | +9.1436 | +0.9194 | |
| Residual / Random | 2 models | +2.2298 | +14.4043 | +2.1798 |
| Checkpoint 700057 | Checkpoint 700067 | |||||
|---|---|---|---|---|---|---|
| Dose | FID | KID | DINO | FID | KID | DINO |
| 19.3259 | 8.0277 | 214.1753 | 19.6556 | 7.9593 | 221.1238 | |
| 16.4837 | 6.9552 | 176.1563 | 16.5493 | 6.7097 | 180.4755 | |
| 0 (Local) | 14.6940 | 6.2627 | 153.9113 | 14.5998 | 5.9022 | 156.5978 |
| 13.4437 | 5.5216 | 142.4353 | 13.2309 | 5.0992 | 144.1813 | |
| 12.4814 | 4.6672 | 138.1119 | 12.1843 | 4.2334 | 139.3422 | |
| Seed | NFE | Fixed H | Cal. H | Cal. Start | Mixed |
| 700081 | 2 | Local ∗ | Local | Local | Local |
| 700081 | 4 | ||||
| 700081 | 8 | ||||
| 700087 | 2 | Local ∗ | Local | Local | Local |
| 700087 | 4 | ||||
| 700087 | 8 |
| Seed | NFE | Arm | FID | KID | DINO | Prec. | Rec. |
|---|---|---|---|---|---|---|---|
| 700081 | 2 | Local | 15.1220 | 6.2885 | 167.175 | 0.7097 | 0.3176 |
| 700081 | 4 | Local | 14.1230 | 5.6144 | 145.831 | 0.7145 | 0.3684 |
| 700081 | 4 | 13.6702 | 5.2822 | 142.588 | 0.7109 | 0.3803 | |
| 700081 | 4 | 12.6322 | 4.5026 | 139.306 | 0.6953 | 0.4072 | |
| 700081 | 4 | 12.8443 | 3.9415 | 158.941 | 0.6902 | 0.3768 | |
| 700081 | 8 | Local | 13.0614 | 4.7497 | 137.521 | 0.7184 | 0.3905 |
| Seed | NFE | Treatment / reference | FID r1 | FID r2 | KID gain | DINO gain | Gate |
|---|---|---|---|---|---|---|---|
| 700081 | 4 | Fixed H / Local | +0.4531 | +0.4526 | +0.3322 | +3.244 | Pass |
| 700081 | 4 | Cal. H / Local | +1.5073 | +1.4743 | +1.1117 | +6.526 | Pass |
| 700081 | 4 | Cal. H / Start | +0.1650 | +0.2591 | -0.5612 | +19.636 | Pass |
| 700081 | 8 | Fixed H / Local | +0.0512 | +0.0544 | +0.0459 | +0.223 | Pass |
| 700081 | 8 | Cal. H / Start | -0.1095 | -0.0738 | -0.3317 | +4.507 | Fail |
| 700087 | 4 | Fixed H / Local | +0.4771 | +0.4779 | +0.3441 | +2.733 | Pass |
| Agreement with 5k choice | Confirmation FID difference | |||||
|---|---|---|---|---|---|---|
| NFE | Seed | 500 | 1k | 2k | 1k | 2k |
| 4 | 700081 | 19/20 | 20/20 | 20/20 | +0.00000 | +0.00000 |
| 4 | 700087 | 20/20 | 20/20 | 20/20 | +0.00000 | +0.00000 |
| 8 | 700081 | 6/20 | 10/20 | 14/20 | +0.04582 | +0.02749 |
| 8 | 700087 | 4/20 | 6/20 | 9/20 | +0.00539 | +0.00423 |
| FID gain r1 | FID gain r2 | Mean FID gain | IS retention | ||
|---|---|---|---|---|---|
| 0.00 | 0.30 | -0.1171 | -0.0992 | -0.1081 | 0.9817 |
| 0.00 | 0.50 | -2.8806 | -2.9079 | -2.8942 | 0.8698 |
| 0.25 | 0.30 | -0.0518 | -0.0280 | -0.0399 | 0.9947 |
| 0.25 | 0.50 | -2.2329 | -2.1834 | -2.2082 | 0.8608 |
| 0.50 | 0.30 | +0.0016 | +0.0064 | +0.0040 | 0.9790 |
| 0.50 | 0.50 | -1.1703 | -1.1361 | -1.1532 | 0.8744 |
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