<p>I'm pretty sure that <span class="math-container">$\mathrm{cl}$</span> is the <a href="https://en.wikipedia.org/wiki/Closure_operator" rel="nofollow noreferrer">set closure</a> operation. I'm less sure about <span class="math-container">$\mathrm{co}$</span>, but I've seen it being used for the <a href="https://en.wikipedia.org/wiki/Convex_hull" rel="nofollow noreferrer">convex hull</a> operation in other contexts.</p>

<p>As a reference, in <em><a href="https://books.google.ca/books?id=hIYKBwAAQBAJ&amp;pg=PA31&amp;lpg=PA31&amp;dq=cl+co+set+operation&amp;source=bl&amp;ots=POncdMbvG0&amp;sig=ACfU3U0n6qwugWFJapEVzp6swCtGXX8QWw&amp;hl=en&amp;sa=X&amp;ved=2ahUKEwj5ubekmPbjAhVHs54KHaurA9IQ6AEwAHoECAcQAQ#v=onepage&amp;q=cl%20co%20set%20operation&amp;f=false" rel="nofollow noreferrer">Fundamentals of Convex Analysis</a></em>, the same notations are used to refer to the <strong>closed convex hull</strong> of a set: </p>

<p><a href="https://i.sstatic.net/l3ta2.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/l3ta2.png" alt="enter image description here"></a></p>

CC BY-SA 4.0
2019-08-09T16:27:40.970Z
2019-08-09T16:27:40.970Z
Herr K.
<p>I stumbled upon this notation, (cl co(A+C), while reading "Set Optimization—A Rather Short Introduction" by Andreas H. Hamel, Frank Heyde, Andreas Löhne, Birgit Rudloff and Carola Schrage.</p>

<p>Is it right for me to assume that cl co(A) means the convex closure of the set A?</p>

<p><a href="https://i.sstatic.net/s6tBy.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/s6tBy.png" alt="enter image description here"></a></p>

<microeconomics><mathematical-economics><theory>
The notation cl co (A)
Yejin
# The notation cl co (A)

(Asked by: username_0 on 2019-08-09)

I stumbled upon this notation, (cl co(A+C), while reading "Set Optimization—A Rather Short Introduction" by Andreas H. Hamel, Frank Heyde, Andreas Löhne, Birgit Rudloff and Carola Schrage.

Is it right for me to assume that cl co(A) means the convex closure of the set A?

[![enter image description here](https://i.sstatic.net/s6tBy.png)](https://i.sstatic.net/s6tBy.png)

**Tags:** microeconomics, mathematical-economics, theory

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## 1 answers

### Answer by username_1 on 2019-08-09. Score: 2 | Accepted answer

I'm pretty sure that $\mathrm{cl}$ is the [set closure](https://en.wikipedia.org/wiki/Closure_operator) operation. I'm less sure about $\mathrm{co}$, but I've seen it being used for the [convex hull](https://en.wikipedia.org/wiki/Convex_hull) operation in other contexts.

As a reference, in *[Fundamentals of Convex Analysis](https://books.google.ca/books?id=hIYKBwAAQBAJ&pg=PA31&lpg=PA31&dq=cl+co+set+operation&source=bl&ots=POncdMbvG0&sig=ACfU3U0n6qwugWFJapEVzp6swCtGXX8QWw&hl=en&sa=X&ved=2ahUKEwj5ubekmPbjAhVHs54KHaurA9IQ6AEwAHoECAcQAQ#v=onepage&q=cl%20co%20set%20operation&f=false)*, the same notations are used to refer to the **closed convex hull** of a set:

[![enter image description here](https://i.sstatic.net/l3ta2.png)](https://i.sstatic.net/l3ta2.png)


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