Differential equations are a powerful tool for modeling the continuous change of a system over time. They are used in various fields, including physics, engineering, and psychology, to describe the evolution of dynamic systems.

In a Markov chain, the probability of transitioning from state $i$ to state $j$ in $n$ steps is given by the $n$-th power of the transition probability matrix $P$, denoted as $P_{ij}^n$.

Q-Learning is a popular reinforcement learning algorithm that estimates the optimal action-value function $Q(s, a)$ for each state-action pair, allowing it to learn optimal policies in a sequential decision-making environment.

In the context of behavior change, reinforcement refers to a positive or negative consequence that follows a behavior, which can influence the likelihood of that behavior being repeated or discontinued.

The SIR model is a mathematical model used to describe the spread of an infectious disease through a population. It divides the population into three compartments: Susceptible, Infected, and Recovered.

In a differential equation model of behavior change, the term 'drift' represents the rate of change of the behavior over time, which is typically influenced by various factors such as reinforcement, punishment, and environmental cues.

A fixed ratio schedule is a type of reinforcement schedule in which a reinforcer is delivered after a fixed number of responses. This schedule can be effective in increasing the rate of responding.

In a Markov chain model of behavior change, the probability of being in state $j$ at time $t$ given that the system started in state $i$ at time $0$ is given by $P_{ij}(t)$, which is an element of the transition probability matrix raised to the power of $t$.

The logistic equation is a type of differential equation model used to describe the dynamics of a population. It is a non-linear equation that captures the growth and decline of a population over time.

The exploration-exploitation trade-off is a fundamental challenge in reinforcement learning. It refers to the balance between trying new actions to explore the environment and sticking to known good actions to exploit the knowledge gained so far.

A hidden Markov model (HMM) is a type of Markov chain model used to describe the evolution of a system over time. It is characterized by the fact that the states of the system are not directly observable, and instead, only the observations of the system are available.

In the context of behavior change, extinction refers to the complete cessation of a behavior. It occurs when a behavior is no longer reinforced and eventually disappears.

Value iteration is a type of reinforcement learning algorithm that uses a value function to estimate the expected long-term reward of taking a particular action in a given state. It iteratively updates the value function until it converges to the optimal values.

In a SEIR model of infectious disease spread, the 'E' stands for 'Exposed'. This compartment represents individuals who have been exposed to the disease but are not yet infectious.

Difference equations are a type of mathematical model used to describe the evolution of a system over time. They are similar to differential equations, but they are used to model discrete-time systems, where the state of the system changes at specific intervals.