<p>I assume this is an iterative function. It means the current <span class="math-container">$V(S_t)$</span> <strong>is</strong> the sum of the previous plus some adjustment. The arrow is like an <strong>assignment</strong>.</p>

<p>In code, you would do</p>

<pre><code>vst = vst + alpha * (gt - vst)
</code></pre>

<p>So <code>vst</code> will be overwritten. </p>

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2020-02-16T17:44:46.053Z
2020-02-16T20:07:49.210Z
2020-02-16T20:07:49.210Z
Dirk N
<p>What is the purpose of the arrow <span class="math-container">$\leftarrow$</span> in the formula below? </p>

<p><span class="math-container">$$V(S_t) \leftarrow V(S_t) + \alpha \left[ G_t - V(S_t) \right]$$</span></p>

<p>I presume it's not the same as 'equals'.</p>

<reinforcement-learning><notation><value-functions>
What is the purpose of the arrow $\leftarrow$ in this formula?
mason7663
# What is the purpose of the arrow $\leftarrow$ in this formula?

(Asked by: username_0 on 2020-02-16)

What is the purpose of the arrow $\leftarrow$ in the formula below?

$$V(S\_t) \leftarrow V(S\_t) + \alpha \left[ G\_t - V(S\_t) \right]$$

I presume it's not the same as 'equals'.

**Tags:** reinforcement-learning, notation, value-functions


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## 1 answers

### Answer by username_1 on 2020-02-16. Score: 2 | Accepted answer

I assume this is an iterative function. It means the current $V(S_t)$ is the sum of the previous plus some adjustment. The arrow is like an assignment.
In code, you would do
vst = vst + alpha * (gt - vst)

So vst will be overwritten.


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