RAVEN: Receiver-Conditioned Action-Value Encoding for Finite-Alphabet Multi-Agent Communication
Organizations: Xi’an Jiaotong University Xi’an, China
Abstract
A message drawn from a small alphabet helps a teammate only if it keeps the distinctions that change that teammate's next decision. We show that scoring messages by action values averaged over the receiver's situation can erase exactly these distinctions, and we propose RAVEN (Receiver-conditioned Action-Value ENcoding), which trains a four-symbol, one-step-delayed channel to preserve each receiver's centered action-value profile within the receiver's own context. The sender never needs to know that context: the receiver decodes every symbol with its private information. We give two estimators of this target. With a teacher, offline RAVEN selects the codebook that exactly minimizes an empirical conditional distortion and distills it into a frozen sender; we bound the resulting codebook-selection error and one-step decision loss. Without a teacher, online RAVEN aligns, inside a QMIX learner, the deployed symbol pathway with a training-only continuous reference that shares its routing. Against five recent communication methods on eight navigation settings, offline RAVEN attains the highest return in seven, and removing receiver conditioning forfeits 83% of its communication gain. Online RAVEN raises predator-prey capture success from 53.2% to 96.0% over the same QMIX backbone without communication, and on SMAC and MPE it attains the best mean normalized score of 14 methods, including methods that exchange kilobit messages. Every RAVEN message costs 2 bits, 12-1,024x fewer than those of NDQ, CACOM and ExpoComm on navigation.
Figures & tables
| Setting | RAVEN off | RAVEN on | SLIM | NDQ | CACOM | ExpoComm | (ub) | no msg. | learn. ch. |
| N1-C2 (2 agents, pair) | 9.59 ±0.60 | 12.35 ±1.68 | 18.81 ±0.76 | 21.34 ±1.87 | 17.25 ±0.97 | 14.98 ±1.44 | 8.52 ±0.16 | 19.27 ±0.19 | 14.49 ±0.65 |
| N1-C3 (3 agents, ring) | 11.47 ±0.39 | 15.21 ±2.78 | 18.79 ±0.71 | 19.98 ±0.95 | 17.84 ±0.15 | 17.35 ±0.92 | – | – | – |
| N1-C4 (4 agents, ring) | 13.74 ±0.64 | 17.86 ±0.30 | 20.02 ±0.85 | 20.06 ±0.67 | 17.89 ±0.44 | 17.92 ±0.30 | – | – | – |
| N1-C6 (6 agents, ring) | 18.15 ±0.12 | 17.96 ±0.23 | 20.13 ±0.72 | 24.32 ±3.55 | 17.78 ±0.28 | 17.94 ±0.26 | – | – | – |
| N2-L1 (1 listener) | 7.70 ±0.17 | 7.86 ±0.24 | 11.89 ±3.01 | 14.19 ±3.02 | 12.64 ±4.32 | 15.42 ±0.28 | – | – | – |
| N2-L2 (2 listeners) | 7.86 | 9.13 ±1.87 | 12.10 | 15.08 ±2.78 | 9.65 ±3.58 | 14.16 ±2.39 | – | – | – |
| Method | 3m | 8m | MMM | MMM2 | 3s5z | Spread | Tag | Crypto | Bits/msg | Norm. | Rank |
|---|---|---|---|---|---|---|---|---|---|---|---|
| RAVEN on | 99.72 ±0.22 | 99.95 ±0.06 | 100.0 ±0.0 | 87.35 ±8.30 | 97.80 ±1.12 | 29.00 ±0.59 | 277.3 ±3.0 | 48.03 ±0.04 | 2 | 0.98 | 1.75 |
| QMIX ( Rashid et al., 2018 ) | 99.80 | 98.80 | 98.60 | 57.80 | 86.40 | 43.42 | 23.39 | 0.38 | 0 | 0.74 | 7.3 |
| QPLEX ( Wang et al., 2021b ) | 99.75 | 99.50 | 30.75 | 62.00 | 96.50 | 31.57 | 235.1 | 45.44 | 0 | 0.80 | 5.0 |
| TeamComm ( Yang et al., 2024 ) | 99.25 | 99.00 | 98.00 | 64.25 | 91.00 | 43.73 | 68.56 | 48.00 | 2,048 | 0.84 | 5.6 |
| TGCNet ( Zhang et al., 2025 ) | 99.00 | 99.25 | 74.00 | 66.50 | 96.75 | 44.95 | 55.46 | 48.00 | 2,048 | 0.80 | 5.9 |
| CACOM ( Li and Zhang, 2024 ) | 96.25 | 43.50 | 98.75 | 34.25 | 97.25 | 48.47 | 251.1 | 3.18 | 16 | 0.67 | 8.1 |
| vs. | Bits/msg | FLOPs | Params | Train time |
|---|---|---|---|---|
| RAVEN off , navigation | ||||
| SLIM | same | – | 95.6–98.0 | 39.6–55.4 |
| NDQ | 97.9 | 82.2–96.8 | 1.4 – 85.1 | – |
| CACOM | 91.7 | 85.8–97.7 | 2.1 – 85.0 | – |
| ExpoComm | 99.9 | 91.5–98.3 | 48.4–92.3 | – |
| RAVEN on , navigation | ||||
Appendix figures & tables30 assets
Supplementary material from the paper’s appendix.
Appendix
| Symbol | Meaning |
|---|---|
| , | number of agents; alphabet size (2 bits per message) |
| , | permitted local input and symbol of sender at step |
| , | local information and mailbox of receiver |
| , | legal actions of receiver ; centering matrix |
| , , | teacher, its input at the arrival time, partner-action reference |
| Task | Agents | Description | Edges | Metric | RAVEN |
|---|---|---|---|---|---|
| N1-C2 reference navigation | 2 | MPE simple_reference : each agent knows only its partner’s goal color; 25 steps | pair, both ways | team return | offline, online |
| N1-C3/C4/C6 ring navigation | 3/4/6 | each agent’s goal is known only to its predecessor | predecessor successor | team return | offline, online |
| N2-L1/L2/L4/L6 broadcast | MPE simple_speaker_listener : an immobile speaker sees the target; listeners see landmarks | speaker listeners | listener return | offline, online | |
| Predator–prey PP1 | 3 | grid, vision radius 1; all agents must reach the same target within 20 steps | all-to-all | capture success | online |
| SMAC 3m, 8m, MMM, MMM2, 3s5z | 3/8/10/10/8 | StarCraft II micromanagement ( Samvelyan et al., 2019 ) ; MMM2 super hard, 3s5z hard | all-to-all, receiver keeps 2 | win rate | online |
| MPE Spread, Tag, Crypto | 3/4/3 | coverage, pursuit and encrypted signaling; in Crypto the eavesdropper Eve is controlled like the other agents and her reward is included in the summed team return; 25 steps | all-to-all | team return | online |
| Setting | RAVEN (offline) | RAVEN (online) | SLIM | NDQ | CACOM | ExpoComm | MACC |
|---|---|---|---|---|---|---|---|
| N1-C2 | 9.59 ±0.60 | 12.35 ±1.68 | 18.81 ±0.76 | 21.34 ±1.87 | 17.25 ±0.97 | 14.98 ±1.44 | 48.12 ±7.75 |
| N1-C3 | 11.47 ±0.39 | 15.21 ±2.78 | 18.79 ±0.71 | 19.98 ±0.95 | 17.84 ±0.15 | 17.35 ±0.92 | 43.44 ±15.20 |
| N1-C4 | 13.74 ±0.64 | 17.86 ±0.30 | 20.02 ±0.85 | 20.06 ±0.67 | 17.89 ±0.44 | 17.92 ±0.30 | 49.47 ±6.68 |
| N1-C6 | 18.15 ±0.12 | 17.96 ±0.23 | 20.13 ±0.72 | 24.32 ±3.55 | 17.78 ±0.28 | 17.94 ±0.26 | 37.97 ±6.34 |
| N2-L1 | 7.70 ±0.17 | 7.86 ±0.24 | 11.89 ±3.01 | 14.19 ±3.02 | 12.64 ±4.32 | 15.42 ±0.28 | 129.72 ±58.17 |
| N2-L2 | 7.86 ±0.14 ‡ | 9.13 ±1.87 | 12.10 ±2.92 ‡ | 15.08 ±2.78 | 9.65 ±3.58 | 14.16 ±2.39 | 115.26 ±71.17 |
| RAVEN (offline) minus … | ||||||
|---|---|---|---|---|---|---|
| Setting | SLIM | NDQ | CACOM | ExpoComm | MACC | |
| N1-C2 | 9.22 ∗∗∗ (5/0) | 11.75 ∗∗∗ (5/0) | 7.66 ∗∗∗ (5/0) | 5.39 ∗∗∗ (5/0) | 38.54 ∗∗ (5/0) | |
| N1-C3 | 7.32 ∗∗∗ (5/0) | 8.51 ∗∗∗ (5/0) | 6.37 ∗∗∗ (5/0) | 5.88 ∗∗∗ (5/0) | 31.97 ∗ (5/0) | |
| N1-C4 | 6.28 ∗∗∗ (5/0) | 6.32 ∗∗∗ (5/0) | 4.15 ∗∗∗ (5/0) | 4.18 ∗∗∗ (5/0) | 35.73 ∗∗ (5/0) | |
| N1-C6 | 1.97 ∗∗ (5/0) | 6.17 † (5/0) | 0.38 † (1/4) | 0.21 (1/4) | 19.82 ∗ (5/0) | |
| N2-L1 | 4.19 † (4/1) | 6.49 ∗∗ (5/0) | 4.94 † (4/1) | 7.72 ∗∗∗ (5/0) | 122.02 ∗ (5/0) | |
| Setting | RAVEN (online) | CACOM | ExpoComm | MACC |
|---|---|---|---|---|
| N1-C3 | 17.03 | 18.19 | 18.10 | 46.92 |
| N1-C4 | 18.12 | 18.47 | 18.29 | 47.44 |
| N1-C6 | 18.32 | 18.87 | 18.26 | 38.22 |
| N2-L2 | 12.54 | 11.95 | 15.35 | 115.92 |
| N2-L4 | 12.48 | 13.01 | 15.68 | 135.90 |
| N2-L6 | 13.69 | 15.88 | 16.18 | 148.49 |
| development seeds | fresh seeds | gain from messages | ||||
|---|---|---|---|---|---|---|
| Setting | seeds | seeds | RAVEN | SLIM | ||
| N1-C3 | 7.04 | 5/5 | 7.32 | 5/5 | 6.44 | 1.17 |
| N1-C4 | 5.52 | 5/5 | 6.28 | 5/5 | 4.64 | 0.49 |
| N1-C6 | 2.49 | 5/5 | 1.97 | 5/5 | 0.41 | 0.28 |
| RAVEN (offline) | SLIM | CACOM | ExpoComm | |||
|---|---|---|---|---|---|---|
| Setting | zero-shot | zero-shot | zero-shot | retrained | zero-shot | retrained |
| N2-L2 | 7.86 | 12.10 | 12.96 | 9.65 | 15.78 | 14.16 |
| N2-L4 | 7.92 | 12.19 | 12.94 | 10.68 | 15.75 | 13.66 |
| N2-L6 | 7.82 | 12.26 | 12.95 | 13.81 | 15.78 | 13.98 |
| K = 4 (2 bits) | K = 2 (1 bit) | ||||||
|---|---|---|---|---|---|---|---|
| Variant | changes | return | seeds / | (Holm) | return | ||
| RAVEN (offline), full | – | 9.45 ±0.46 | – | – | – | 14.78 | – |
| local-residual target + geometric condition | target and condition | 10.75 ±1.72 | 1.30 [0.10, 2.50] | 7/2 | 0.146 | 15.31 | 0.53 |
| geometric receiver condition | condition | 13.54 ±1.79 | 4.09 [2.85, 5.32] | 10/0 | 16.12 | 1.33 | |
| plain learnable 4-symbol channel (no codebook) | codebook construction | 14.49 ±0.65 | 5.04 [4.62, 5.46] | 10/0 | 16.80 | 2.02 | |
| sender unfrozen after distillation | sender freezing | 14.57 ±0.99 | 5.12 [4.53, 5.72] | 10/0 | 17.37 | 2.59 ∘ | |
| all four methods | controls only | |||
|---|---|---|---|---|
| Diagnostic | K=4 | K=2 | K=4 | K=2 |
| total risk | 0.833 / 0.76 | 0.800 / 0.72 | 0.667 / 0.40 | 0.633 / 0.35 |
| abstraction term | 0.850 / 0.78 | 0.817 / 0.72 | 0.700 / 0.45 | 0.667 / 0.35 |
| compression term | 0.800 / 0.72 | 0.617 / 0.26 | 0.867 / 0.80 | 0.833 / 0.70 |
| teacher-action regret | 0.783 / 0.72 | 0.767 / 0.66 | 0.767 / 0.65 | 0.767 / 0.60 |
| Method | every step | every 2 | every 4 | once | 10% loss | 30% loss |
|---|---|---|---|---|---|---|
| bytes / episode | 50 | 26 | 14 | 2 | 50 | 50 |
| RAVEN (offline), full | 9.78 | 9.78 | 9.79 | 9.84 | 9.80 | 9.88 |
| local-residual target + geometric condition | 11.60 | 11.60 | 11.61 | 11.71 | 11.62 | 11.68 |
| geometric receiver condition | 14.20 | 14.22 | 14.24 | 14.37 | 14.22 | 14.25 |
| plain learnable 4-symbol channel (no codebook) | 15.05 | 15.10 | 15.15 | 15.73 | 15.07 | 15.10 |
| Task | Metric | Control | RAVEN | control | [95% CI] | seeds / | |
|---|---|---|---|---|---|---|---|
| Predator–prey PP1 | capture success (%) | same-backbone QMIX | 96.04 | 53.20 | 42.84 [15.5, 70.2] | 5/0 | 0.024 |
| MPE Spread | team return | same-backbone QMIX | 29.00 | 31.87 | 2.87 [1.77, 3.97] | 5/0 | 0.002 |
| MPE Spread | team return | w/o reference TD loss | 28.83 | 29.52 | 0.69 [0.06, 1.32] | 3/0 | 0.043 |
| Method | 3m | 8m | MMM | MMM2 | 3s5z | Spread | Tag | Crypto | norm. | rank |
|---|---|---|---|---|---|---|---|---|---|---|
| RAVEN (online) | 99.72 ±0.22 | 99.95 ±0.06 | 100.00 ±0.00 | 87.35 ±8.30 | 97.80 ±1.12 | 29.00 ±0.59 | 277.3 ±3.0 | 48.03 ±0.04 | 0.98 | 1.75 |
| QMIX | 99.80 | 98.80 | 98.60 | 57.80 | 86.40 | 43.42 | 23.39 | 0.38 | 0.74 | 7.3 |
| QMIX (large) | 97.57 | 99.31 | 96.88 | 26.91 | 94.91 | 44.17 | 46.04 | 21.69 | 0.70 | 8.6 |
| QPLEX | 99.75 | 99.50 | 30.75 | 62.00 | 96.50 | 31.57 | 235.1 | 45.44 | 0.80 | 5.0 |
| OW-QMIX | 100.00 | 96.20 | 98.00 | 38.75 | 89.60 | 51.50 | 51.09 | 8.70 | 0.69 | 8.6 |
| CW-QMIX | 98.00 | 96.50 | 96.00 | 2.25 | 80.50 | 49.39 | 22.87 | 47.21 | 0.69 | 9.9 |
| Method | 3m | 8m | MMM | MMM2 | 3s5z |
|---|---|---|---|---|---|
| RAVEN (online) | 92.5 / 0.25 | 93.2 / 0.25 | 92.8 / 0.30 | 44.8 / 1.50 | 61.4 / 1.20 |
| QMIX | 90.8 / 0.40 | 93.1 / 0.15 | 86.3 / 0.45 | 29.3 / – | 59.1 / 1.15 |
| QPLEX | 97.8 / 0.15 | 97.2 / 0.10 | 86.9 / 0.30 | 25.9 / – | 90.0 / 0.30 |
| QMIX+TeamComm | 82.1 / 0.60 | 91.9 / 0.20 | 88.7 / 0.35 | 34.8 / – | 64.8 / 1.00 |
| QMIX+TGCNet | 78.6 / 0.60 | 93.1 / 0.30 | 84.0 / 0.50 | 42.5 / – | 67.3 / 1.00 |
| CACOM | 92.2 / 0.20 | 38.9 / – | 82.9 / 0.45 | 12.4 / – | 64.7 / 0.90 |
| RAVEN | vs. | params | exec. FLOPs | bits / message | measured traffic | training time |
|---|---|---|---|---|---|---|
| RAVEN (offline) | SLIM | 95.6 / 98.0 | – | 0.00 | – | 39.6 / 55.4 |
| RAVEN (offline) | NDQ | 1.4 / 85.1 | 82.2 / 96.8 | 97.92 | – | – |
| RAVEN (offline) | CACOM | 2.1 / 85.0 | 85.8 / 97.7 | 91.67 | – | – |
| RAVEN (offline) | ExpoComm | 48.4 / 92.3 | 91.5 / 98.3 | 99.90 | – | – |
| RAVEN (offline) | MACC | 229.0 / 50.9 | 45.4 / 89.3 | 0.00 | – | – |
| RAVEN (online) | SLIM | 81.7 / 81.8 | – | 0.00 | – | – |
| Setting | RAVEN (offline) | RAVEN (online) | SLIM | NDQ | CACOM | ExpoComm | MACC |
|---|---|---|---|---|---|---|---|
| N1-C2 | 11.7k / 23k | 48.0k / 190k | 264.0k / – | 32.7k / 128k | 32.4k / 160k | 68.0k / 268k | 10.7k / 42k |
| N1-C6 | 35.2k / 68k | 48.3k / 578k | – / – | 34.7k / 409k | 34.5k / 567k | 68.2k / 807k | 10.7k / 125k |
| N2-L1 | 5.3k / 10k | 48.0k / 190k | 264.0k / – | 32.7k / 128k | 32.4k / 160k | 68.0k / 268k | 10.7k / 42k |
| N2-L6 | 5.3k / 16k | 48.3k / 677k | 264.0k / – | 35.2k / 485k | 35.0k / 688k | 68.3k / 943k | 10.7k / 146k |