MullOverThing

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# What is the difference between state value function and action value function?

## What is the difference between state value function and action value function?

That means summarised, the state-value-function returns the value of achieving a certain state and the action-value-function returns the value for choosing an action in a state, whereas a value means the total amount of rewards until reaching terminal state.

### Why do we estimate the state-action value?

The reason we want to estimate these value functions is so that they can be used to accurately choose an action that will provide the best total reward possible, after being in that given state. The value functions are updated using results from executing actions determined by some policy.

#### What is the difference between value function and Q function?

We use a Value function (V) to measure how good a certain state is, in terms of expected cumulative reward, for an agent following a certain policy. A Q-value function (Q) shows us how good a certain action is, given a state, for an agent following a policy.

What is state value function in reinforcement learning?

Almost all reinforcement learning algorithms are based on estimating value functions–functions of states (or of state-action pairs) that estimate how good it is for the agent to be in a given state (or how good it is to perform a given action in a given state).

How do you calculate state value?

In other words: the value of a state, when following policy ‘π’, is equal to the sum, over all actions from that state, of the probability of taking each action, times the immediate reward for that action plus the discounted value of the next state where we end up after taking the action.

## What is Q value in RL?

Q Value (Q Function): Usually denoted as Q(s,a) (sometimes with a π subscript, and sometimes as Q(s,a; θ) in Deep RL), Q Value is a measure of the overall expected reward assuming the Agent is in state s and performs action a, and then continues playing until the end of the episode following some policy π.

### Is Q function a value function?

In general, a value function is any function that returns expected rewards given some relevant data. The Q value is the expected reward given a state-action pair, and the Q function is a function that produces Q values when given a state-action pair.

#### What is RL 500ml?

Ringer’s lactate solution (RL), also known as sodium lactate solution and Hartmann’s solution, is a mixture of sodium chloride, sodium lactate, potassium chloride, and calcium chloride in water. It is used for replacing fluids and electrolytes in those who have low blood volume or low blood pressure.

What do you call a state value function?

State value function A state value function is also called simply a value function. It specifies how good it is for an agent to be in a particular state with a policy π. A value function is often denoted by V(s). It denotes the value of a state following a policy.

What is the difference between a state value and a state action value?

The state value function, , is the expected return when starting in state and following thereafter. Similarly, the state-action value function, , is the expected return of when starting in state , taking action , and following policy thereafter. Read these 3 times out loud and you’ll get the difference.

## What is the return of a state value?

Similarly, the state-action value function, [math]Q_pi(s, a)math], is the expected return of when starting in state [math]s[/math], taking action [math]a[/math], and following policy [math]pi[/math] thereafter.

### What is the Q function of a state?

State-action value function (Q function) A state-action value function is also called the Q function. It specifies how good it is for an agent to perform a particular action in a state with a policy π.