Research map / Multi-agent systems and games / Games and equilibria
Adaptive Sample Sharing for Multi Agent Linear Bandits
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Proposes BASS, a multi-agent linear bandit algorithm that adaptively shares samples between agents using an anisotropic (Mahalanobis) ellipsoid-separation test, with no cluster assumption, and proves separation-time and regret bounds.
Problem
Regret minimization in heterogeneous multi-agent linear stochastic bandits, where agents must decide when sharing observations reduces variance more than it introduces bias from differing bandit parameters.
Approach
Decides collaboration between agent pairs via a Mahalanobis-based ellipsoid separation test (gamma-relaxed function Psi) built on the design matrices, so sharing stops once parameter bias exceeds the current uncertainty in the directions of large reward, without assuming a cluster structure.
Key results
- On synthetic environment with Delta_min=0.2, BASS (delta=0.1) reaches cumulative regret 1096.8 vs 6100.7 for independent agents and 5765.5 for DynUCB (Oracle 318.5).
- On MovieLens, BASS (delta=0.1) attains cumulative regret 10273.2 vs 11825.2 for Ind and 11504.2 for CLUB.
- BASS achieves the best clustering F1 (0.7 to 0.9) in synthetic settings, while CLUB, SCLUB and CMLB score 0.0 in most settings.
Measured effects reported in the paper
| What was changed | Where | Measured | Effect |
|---|---|---|---|
| Use BASS instead of independent agents (Ind) | Multi-agent linear bandits · Synthetic (Δminθ,2=0.2) | cumulative regret: 6100.7 +/- 468.4 -> 1096.8 +/- 411.9 | Helped |
| Use BASS instead of independent agents (Ind) | Multi-agent linear bandits · Synthetic (Δminθ,2=1.27) | cumulative regret: 5465.0 +/- 352.7 -> 1563.2 +/- 750.7 | Helped |
| Use BASS instead of SCLUB (γ=1.0) | Multi-agent linear bandits · MovieLens | cumulative regret: 11085.5 +/- 701.3 -> 10273.2 +/- 686.3 | Helped |
| Use BASS instead of CLUB (γ=0.1) | Multi-agent linear bandits · Yahoo | cumulative regret: 13321.5 +/- 4228.8 -> 12456.0 +/- 2096.1 | Helped |
| Use BASS (δ=0.1) instead of DynUCB | Multi-agent linear bandits · Synthetic (Δminθ,2=0.2) | F1 score: 0.7 +/- 0.1 -> 0.7 +/- 0.0 | Mixed |
| Use BASS (δ=0.1) instead of DynUCB | Multi-agent linear bandits · Synthetic (Δminθ,2=1.27) | F1 score: 0.9 +/- 0.2 -> 0.9 +/- 0.0 | No clear effect |
Surprising findings
- Most cluster-based baselines (CLUB, SCLUB, CMLB) recover the cluster structure poorly, with F1 near 0 in most synthetic settings.
- Under the synthetic setting with Delta_min=0.2, CMLB with gamma=Delta/2 performs no better than independent agents.
Limitations
- Theoretical bounds rely on synchronous pulling and sub-Gaussian noise assumptions; the algorithm is analyzed for two-agent pairs and extended to N agents by pairwise consideration.
- Empirical evaluation uses a single synthetic setting with M=3 clusters and a few real datasets; the paper notes the clustering error bound is loose (exponent depends on gamma^2 R^2 - 1).
Experimental setup
Datasets: MovieLens Yahoo!
Benchmarks: synthetic clustered linear bandit environment MovieLens ranking Yahoo! ranking
Metrics: cumulative pseudo-regret clustering F1 score
Baselines: Ind Oracle DynUCB CLUB SCLUB CMLB
Builds on: OFUL CLUB overlapping ellipsoid test (Gentile et al.)
Closest papers by meaning
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