Define environment signals
Specify state and action representations, reward function and termination conditions so the model has concrete prediction targets.
Model-based RL environment simulator. Assess simulator fidelity and risks.
Model-based RL builds a predictive model of environment dynamics and uses it to simulate rollouts for policy optimisation. Key issues include model bias, compounding errors in long rollouts, and evaluating simulated trajectories against real environment behaviour.
Learning concept · Not a validated service
Model-based RL builds a predictive model of environment dynamics and uses it to simulate rollouts for policy optimisation. Key issues include model bias, compounding errors in long rollouts, and evaluating simulated trajectories against real environment behaviour.
A proposed application: use an environment model to generate synthetic trajectories that speed up offline policy evaluation and short-term policy search, with humans in the loop to check safety-critical decisions.
Specify state and action representations, reward function and termination conditions so the model has concrete prediction targets.
Gather a small set of trajectories from a reference policy or simulator and split into train/validation for dynamics modelling.
Fit a next-state and reward predictor, measure one-step and multi-step prediction error and inspect failure cases.
Run simulated rollouts to compare candidate policies, tracking return distributions and robustness across seeds.
The supplied starter runs a 4-armed multi-armed-bandit simulation using an epsilon-greedy policy: it samples binary rewards from fixed Bernoulli rates, updates sample-average estimates per arm, and prints action counts, estimated rates and total reward. There is no state, transition model, or environment-dynamics learning implemented.
for step in range(1, 2001):
if rng.random() < epsilon:
action = rng.integers(len(true_reward_rates))
else:
action = int(np.argmax(estimated_values))
reward = 1 if rng.random() < true_reward_rates[action] else 0
action_counts[action] += 1
total_reward += reward
estimated_values[action] += (reward - estimated_values[action]) / action_counts[action]The code implements an epsilon-greedy multi-armed bandit and does not train a dynamics model, simulate state transitions, or produce model-based rollouts. It lacks state, action-conditioned next-state or reward predictors and so cannot demonstrate model-based RL concepts such as planning with learned dynamics.
A proposed extension is to replace fixed Bernoulli arms with a small Markov environment, collect state–action–next-state tuples, train a neural dynamics model and compare policy evaluation under the learned model versus the true environment.
This is a potential application pathway, not a delivered product. The supplied starter does not implement this service or validate it with real users.
Networkers Home runs this topic inside its AI Engineer Course, with placement support and hands-on labs.