# LYX: how to mark power set?

This is my first time here and I did my best to figure out if such a question is in place here. If I missed something I apologize.

My questions is how can I mark a power set in the lyx document editor?

For example: I'd like to write P(A) when A represents a set, but in the special marking normally used for the power set. I assume there should be a '\shortcut' kind of thing, but I'm new to lyx and can't find one.

## migrated from mathoverflow.netNov 24 '14 at 12:44

This question came from our site for professional mathematicians.

• Welcome to TeX.SX! You have been migrated here. Please register to this site with the same account as on mathoverflow.net! Could you please explain a bit, how you would like the P(A) to look like? If necessary, draw a picture. I can't help you on LyX, but many people will be able to write some LaTeX \shortcut (called macro) for you. – LaRiFaRi Nov 24 '14 at 13:49
• There are several common ways to denote power set, for example $\mathcal{P}(A)$, even plain $P(A)$ is fine. Just please do not abuse for this purpose the Weierstraß elliptic function symbol $\wp$, as many clueless people do. – Emil Jeřábek Nov 24 '14 at 15:20
• Thank you both very much. @EmilJeřábek, $\mathcal{P}(A)$ was exactly what I was looking for - Would make a valid answer... That's how it looks in my homework pages. @LaRiFaRi, thanks for naming the macro for me, this will help me a lot in future questions. I was afraid this group didn't like ignorant LYX users as myself, Thanks for the nice welcome... – Yekhezkel Yovel Nov 25 '14 at 9:49
• @EmilJeřábek consider transforming your comment into an answer. It will make it more noticeable for others (and you will get the reputation you deserve). – Stefan van den Akker Apr 2 '17 at 9:19

$\frak{P} (\mathbb{A})$ also works.

Let's assume you want the output of your power set to resemble something like this:

The above requires amssymb to show the special P. For this, "load always" Document > Settings > Math Options > amssymb:

Now, there are a couple of ways to do this:

1. ## Pure LyX

At the start of your document, Insert > Math > Macro... For the newcommandname, type powerset. For the TeX component of the math macro, type \mathbb P, , (\#1). Leave the LyX component of the math macro empty.

Now when you type a regular (inline) math formula (Insert > Math > Inline Formula), typing \powerset changes the input to use your macro:

2. ## Pure LaTeX

\newcommand{\powerset}[1]{\mathbb{P}(#1)}

I find that $\mathcal{P} (\mathbb{A})$ gives me the result I want: