A Markov decision process (MDP) models sequential decisions in a changing environment with uncertainty. An agent observes its present state, selects an action through a policy, receives a reward, and moves toward a subsequent state. The policy depends on the present state, while probabilistic events also influence what happens next. section 5.1.1 section 5.1
An MDP organizes decision-making around five key components:
- Agent — the decision-maker operating within the environment. section 5.1.1
- States — the situations the agent encounters. section 5.1.1
- Actions — the choices available in each state. section 5.1.1
- Rewards — positive or negative feedback from actions and resulting states. section 5.1.1
- Policy — the rule that selects the next action from the present state. section 5.1.1
Dog-training obstacle course
A dog acts as the agent, the obstacle course as the environment, and obstacles as states. Jumping, crawling, or sidestepping are actions; treats or gentle scolding provide rewards. The dog aims to maximize total treats across the course, illustrating how an agent uses interactions to pursue long-term reward. section 5.1.1
MDPs provide the foundation for reinforcement learning. In preference alignment, generation is treated as sequential decision-making so later optimization methods such as proximal policy optimization can favor outputs that better reflect human intent. section 5.1



