Generative advertising in large language model (LLM) responses requires optimizing sponsorship configurations under two strict constraints: the strategic behavior of advertisers and the high cost of stochastic generations. To address this, we propose the Incentive-Aware Multi-Fidelity Mechanism (IAMFM), a unified framework coupling Vickrey-Clarke-Groves (VCG) incentives with Multi-Fidelity Optimization to maximize expected social welfare. We compare two algorithmic instantiations (elimination-based and model-based), revealing their budget-dependent performance trade-offs. Crucially, to make VCG computationally feasible, we introduce Active Counterfactual Optimization, a "warm-start" approach that reuses optimization data for efficient payment calculation. We provide formal guarantees for approximate strategy-proofness and individual rationality, establishing a general approach for incentive-aligned, budget-constrained generative processes. Experiments demonstrate that IAMFM outperforms single-fidelity baselines across diverse budgets.
Figures & tables
Figure 1: Visual Over-Saturation in Generative Advertising (advertisers: Alpha sports jacket and Beta boba). (a) Baseline produces a natural image lacking commercial utility (unbranded cup and jacket). Balanced configurations naturally prioritize a single brand: (b) sharp focus on Alpha logo with a blurred Beta branded cup; (c) prominent Beta logo, pushing Alpha to the periphery. Conversely, extreme parameters (d) cause catastrophic structural collapse, hallucinating an amalgamated “AB” logo onto the boba cup.
Figure 2
Figure 2: Comparison of welfare across all methods. Left: Box plots stratified by token budget summarize performance, showing the median (center line), mean (diamond), interquartile range (box), and outliers (points). All reported statistics include outliers. The IAMFM methods outperform the baselines and reveal a token-budget-dependent shift in the optimal method. Right: Aggregated performance across all budgets. Our proposed multi-fidelity instantiations (IAMFM-MFBO, IAMFM-ASH) show better median performance, while IAMFM-MFBO demonstrates a clear advantage at higher budgets.
Method
Mean Welfare ± Std. Dev.
Low-Budget ( ≤16k tokens)
High-Budget ( ≥32k tokens)
IAMFM-MFBO
186.26 ± 5.02
190.73 ± 5.53
IAMFM-ASH
187.26 ± 6.00
187.43 ± 7.93
UCB Bandit
182.78 ± 4.15
187.04 ± 1.58
Uniform Sampling
184.26 ± 4.62
185.87 ± 2.41
IAMFM-SH
184.42 ± 10.10
185.21 ± 11.68
Table 1: Aggregated performance (mean welfare ± std. dev.) stratified by budget regime. Methods are sorted by High-Budget performance. Bolded are proposed methods.
Budget
IAMFM-MFBO
IAMFM-ASH
IAMFM-SH
UCB Bandit
Uniform Sampling
500
231.25 ± 5.29
233.12 ± 1.97
231.24 ± 3.64
225.41 ± 2.14
228.95 ± 5.45
1,000
232.07 ± 5.86
230.56 ± 5.79
231.96 ± 7.39
229.12 ± 2.87
230.80 ± 5.08
2,000
233.29 ± 7.93
231.99 ± 5.99
233.19 ± 5.40
229.67 ± 4.56
230.56 ± 5.65
4,000
238.24 ± 6.85
231.43 ± 5.20
233.41 ± 5.04
233.14 ± 5.23
232.25 ± 4.85
8,000
240.26 ± 5.92
232.88 ± 5.79
231.48 ± 6.79
235.58 ± 2.16
229.98 ± 5.05
Table 2: Algorithm performance (Mean Welfare ± Std. Dev.) on the Image Generation task across 20 independent trials. IAMFM-MFBO demonstrates a widening performance gap over baselines as the budget scales.
Appendix figures & tables9 assets
Supplementary material from the paper’s appendix.
Appendix
Strength
Label
Description for Prompt
0
Very Weak
minimal presence (indirect references only)
1
Weak
weak presence (subtle, background references)
2
Moderate
moderate presence (balanced, natural integration)
3
Strong
strong presence (prominent, featured examples)
4
Very Strong
very strong presence (dominant, detailed focus)
Appendix
Table 3: Mapping of numerical strength levels to prompt descriptions.
Regime
Comparison
Mean Diff.
p-value
95% CI 3 3 3 We report Welch 95% confidence intervals throughout. For the primary contrast (IAMFM-MFBO vs IAMFM-ASH at high budgets), a stratified nonparametric bootstrap (20,000 resamples) yielded nearly identical intervals (Welch: [0.21, 6.38]; bootstrap: [0.42, 6.33]), supporting the robustness of our conclusions.
Low-Budget ( ≤16k )
IAMFM-MFBO vs. UCB Bandit
+3.48
0.0003
[+1.63, +5.33]
IAMFM-MFBO vs. Uniform
+2.00
0.043
[+0.06, +3.93]
IAMFM-ASH vs. UCB Bandit
+4.47
<0.0001
[+2.40, +6.55]
IAMFM-ASH vs. Uniform
+2.99
0.0069
[+0.84, +5.14]
IAMFM-MFBO vs. IAMFM-ASH
+0.99
0.38 ns
[-3.22, +1.24]
High-Budget ( ≥32k )
IAMFM-MFBO vs. UCB Bandit
+3.69
0.0002
[+1.83, +5.54]
Appendix
Table 4: Statistical significance (Welch’s t-test) for key comparisons across budget regimes. We report p-values and 95% CIs for the mean difference. Bolded methods are our novel proposals.
Figure 3: Qualitative comparison. The naive greedy strategy (Config A) results in disjointed text where one advertiser overpowers the other, leading to hallucinations. IAMFM (Config B) identifies the optimal influence configuration, improving total welfare by +36% through enhanced semantic coherence.
User Weight ( wU )
Optimal s∗=(sA,sB)
E[VA]
E[VB]
E[Vuser]
wU=0.2
(4, 4)
52.41
73.56
60.02
wU=1
(2, 2)
51.59
72.46
63.77
wU=5.0
(2, 4)
44.18
77.17
65.62
Appendix
Table 5: Optimal configuration s∗ for different user utility weights ( wU ), calculated using F4 mean utilities aggregated across all 5 users. Restaurant A is “QuickBite” and B is “Thai Spice Garden”.
Scenario
Optimal s∗=(sA,sB)
E[VA]
E[VB]
A-Only ( argmaxE[VA] )
(3, 0)
52.44
57.07
B-Only ( argmaxE[VB] )
(0, 4)
45.18
77.72
Appendix
Table 6: Optimal configuration s∗ in advertiser-only extreme scenarios, using F4 aggregated means. The optimum is found by maximizing only E[VA] or E[VB] .
Figure 4: Absolute error (compared with the offline ground truth) in finding the best counterfactual welfare as a function of additional budget ( Bcf ). We compare our warm-start methods against their cold-start counterparts. The GP-based methods are shown in blue: ACO-MFBO (solid blue line) and Cold-Start MFBO (dashed blue line). The elimination-based methods are in green: ACO-ASH (solid green line) and Cold-Start ASH (dashed green line).
Figure 5: SAE Steering for promoting ice creams and lemons. Prompt: “Help me plan the perfect movie night tonight with 8 guests coming. What do I need to buy?” Columns steer for ice cream, and rows steer for lemon-related things.
Online advertising studies how digital ads are targeted, ranked, priced, measured, and delivered while balancing budgets, business goals, and user interests.