World models enable large language model (LLM) agents to anticipate action effects and make informed decisions. For generalization, it is desirable for such world models to transfer efficiently to new environments with similar interaction structure and underlying dynamics. Recent approaches encode world dynamics as symbolic rules or executable programs, whose compositional structure in principle affords transfer, but still organize such knowledge around environment-specific objects. To address this limitation, we introduce RoleWorld, a symbolic world modeling approach which uses reusable prototypes and environment-specific parameter values as functional role abstractions to represent how objects behave in interactions. From interaction trajectories, a teacher LLM extracts role prototypes and executable transition rules defined over role instances, together with a skill that guides the actor LLM to use role information in decision making. In a target world, without the teacher, the actor uses this skill together with its current role assignments and parameter estimates, and actively tests a role instance hypothesis through interaction when its uncertainty affects the current decision. Feedback from each action refines role assignments and estimates parameter values online, with no LLM parameter updates and the transition rules held fixed. Experiments on MARS benchmark show that RoleWorld enables robust generalization across environments with significantly altered object behavior, suggesting that functional role abstractions can serve as an effective component for knowledge transfer in world modeling. Project Page: https://future-item.github.io/RoleWorld.
Figures & tables
Figure 1: Overview of RoleWorld . A teacher LLM induces role prototypes, transition rules, and an actor skill from source trajectories. These remain fixed in the target world, where the actor refines role estimates online and tests hypotheses when uncertainty could affect its decision.
Stage
ReAct
IFR
PoE-World
WALL-E
WorldCoder
RoleWorld
Source learning
×
×
×
×
✓
✓
Target learning
×
✓
✓
✓
×
×
Online refinement
×
✓
✓
✓
✓
✓
Table 1: Evaluation stages ( ✓ : yes; × : no). Source learning: at most five episodes in Default; target learning: five per target world before evaluation; online refinement: within each evaluation episode.
Metrics
Mod. Type
Qwen3-8B
GPT-5.6 Luna
ReAct
IFR
PoE- World
WALL-E
World Coder
Ours
ReAct
IFR
PoE- World
WALL-E
World Coder
Ours
Reward
Terrain
2.8±1.6
2.0±0.9
0.4±1.2
2.0±2.2
5.3±1.7
9.4±3.7
4.0±2.5
10.8±1.2
0.8±0.7
8.2±3.1
5.8±1.7
11.4±1.1
Survival
2.0±1.2
3.0±2.0
0.0±1.1
1.3±0.8
2.3±1.4
8.0±2.6
4.9±2.5
9.3±1.5
1.7±2.4
10.2±4.0
3.1±1.7
10.8±2.4
Task Dep.
1.9±1.7
2.2±0.7
1.5±1.6
2.2±1.4
0.8±0.8
6.8±0.8
1.7±1.1
7.7±1.0
1.4±0.8
4.8±2.5
1.2±0.6
8.5±1.5
Terr. Surv.
1.4±1.0
1.7±0.8
0.1±0.7
1.7±3.2
4.4±1.6
8.1±3.3
4.1±1.5
7.8±0.7
2.1±0.9
5.7±2.4
4.3±1.4
11.0±1.7
Terr. Task.
2.1±1.2
3.0±0.7
1.4±1.1
1.7±1.4
3.7±1.5
6.2±2.1
3.8±1.9
6.4±0.8
3.8±0.8
3.8±1.3
4.2±1.4
7.0±1.0
Table 2: Reward and score (%) on the seven MARS variants under the protocols in Table 1 . Column groups indicate the backbone used for all target-world LLM calls.
Metrics
Method
Terrain
Survival
Task Dep.
Terr. Surv.
Terr. Task.
Surv. Task.
All Three
All
Reward
Direct LLM
0.2±1.0
2.0±1.7
0.9±1.4
1.3±1.2
2.0±1.1
0.8±1.4
0.0±1.1
1.0
w/o Skill
0.9±0.8
2.2±1.6
1.3±1.0
2.3±1.5
1.1±0.9
1.2±0.7
−0.3±0.5
1.2
w/o Adaptation
9.7±1.8
8.4±3.1
0.9±0.4
6.2±1.9
4.3±2.4
4.8±2.6
0.2±1.4
4.9
Fixed Role Assignments
6.8±3.1
6.5±3.3
1.4±1.3
7.8±4.1
5.4±1.4
3.7±3.9
2.5±1.7
4.9
w/o Active Verification
8.0±1.9
6.0±4.3
1.2±0.7
7.7±3.1
1.7±1.5
0.9±0.8
−0.5±0.7
3.6
RoleWorld (full)
9.4±3.7
8.0±2.6
6.8±0.8
8.1±3.3
6.2±2.1
4.3±0.8
3.0±1.5
6.5
Table 3: Ablation results and decision-policy comparison on the seven MARS variants. LLM-based variants use Qwen3-8B. All is the arithmetic mean of the per-world means for each metric. Bold indicates the highest mean in each column within each metric.
Figure 2: Controlled validation of role factorization. Role assignments and role parameter values are corrupted separately, while the environment, role prototypes, and transition rules remain fixed. Shaded bands indicate one standard deviation; see Appendix A.5 for details.
Figure 3: Correction of role estimates with fixed role prototypes and transition rules: (a) correcting a role assignment; (b) correcting a role parameter.
Appendix figures & tables2 assets
Supplementary material from the paper’s appendix.
Appendix
Corruption type
Level (%)
Role parameter accuracy
Prediction discrepancy
100
300
0
100
300
Role parameters
30
87.27±3.77
87.27±4.23
34.19±4.22
6.81±2.09
6.00±1.93
50
79.09±6.88
79.55±7.01
45.15±3.84
10.95±2.83
9.68±2.80
70
70.91±3.50
74.55±4.78
48.79±2.59
15.33±3.84
12.30±3.56
90
58.79±7.10
65.45±5.75
51.29±1.25
19.85±3.53
14.98±2.81
Role assignments
30
92.27±3.93
96.52±2.11
29.89±4.26
4.69±2.18
1.88±1.92
Appendix
Table 4: Controlled validation results (mean ± sample standard deviation across six random seeds). Column subheadings give the active-interaction budget; both metrics are reported as percentages.
Prior
Deterministic mismatches
Missing predictions
Case mean TV
Assignment mean TV
Reference
0
0
0.0410
0.0421
Remove tree/R1
19
19
3.2889
3.3754
Require tool for tree
12
0
2.0923
2.1474
Change wood cost
7
0
1.2376
2.1633
Remove workstation requirement
4
0
0.7248
1.0677
Allow planting on sand
4
0
0.7248
0.2802
Appendix
Table 5: Environment-transition validation of the frozen reference prior and independent single-error controls. Deterministic mismatches are counted over 566 cases and include missing predictions. Both TV averages cover all 585 cases and are reported as percentages.