LyX ⇒ Numbering Equations by Theorem

[Randolf]

Hey,

in LyX, I know how to insert numbered equations so that I have the number of the equation written in the marginal, like this:

equation-numbering-theorem.png (16.15 KiB) Viewed 4047 times

As you can see, the number in the second theorem is (2) because I have already used the "numbered equation" once in my document. I want this counter to reset for each theorem. That is, in my example, both of the numbers should be (1).

ps. If possible, I'd prefer if this could be done purely by using the LyX interface.

[Stefan Kottwitz]

The package chngcntr supports such customization, besides low level LaTeX commands. You could write in your document preable, which you can modify via the LyX menu Document / Settings

Code: Select all

\usepackage{chngcntr}
\counterwithin*{equation}{theorem}

If your theorem counter had another name, use that one in the second line.

Note, that it's difficult to understand references, if you have several equations (1). It could be a good idea to label them together with the theorem number, such as (1.2.1) if at all - I would number then independently of theorems. Perhaps I would not number at all, if they are not referenced, just displayed in theorems.

Stefan

[Randolf]

Thank you Stefan, what you said worked well.

Note, that it's difficult to understand references, if you have several equations (1). It could be a good idea to label them together with the theorem number, such as (1.2.1) if at all - I would number then independently of theorems. Perhaps I would not number at all, if they are not referenced, just displayed in theorems.
Stefan

Yes, I realised it wouldn't be easy to understand where I was referencing by say "equation (5)" if I had multiple equations labeled as (5).
However, I'm planning to use this numbering only to make it easier for the reader to follow my proofs. Say, if I wanted to prove the Pythagora's Theorem, I could label the equation as (1), and start my proof by "To prove the theorem, it suffices to show that (1) holds for all positive numbers."
Of course, in such simple case this this kind of numbering is unnecessary but I have found it helpful in cases that have lots of conditions and equations.