I am writing a latex document in French using Lyx. My problem is the following : using the Theorems (AMS) Lyx module, I would like the "prop" theorem environment to show up as "Propriété" in my latex document rather than "Proposition".

Is there a simple way for me to modify the "prop" environment in the preamble ?

I know I could simply create a new theorem environment and name it "Propriété", but this would force me to use ERT in Lyx whenever I want to write a new "Propriété", which defeats the purpose of using Lyx (unless someone knows a simple way to modify the Lyx module in order for my "Propriété" environment to show up in the drop-down menu).

I hope my question is clear ! Let me know if it isn't. Basically I want to do the simplest thing possible that would allow me to have a theorem environment in the Lyx drop-down menu that shows up as "Propriété" in the final PDF document.

1 Answer 1


I can offer you a relatively easy ERT solution.

The name of the theorem is defined in the variable \propositionname, which in English is set as Proposition. The standard french translation offered by babel is Proposition, but you can redefine that by adding (somewhere before you use the first proposition):


The way I see it, if you want a new theorem in your drop-down menu, it would need to be added to the amsthm package or at least it's not going to be easy. You could of course try to modify the translation directly in the babel package, but I wouldn't recommend that.

  • Thank you very much ! This is exactly the type of solution I was looking for.
    – SignalPost
    Commented Aug 26, 2020 at 14:00

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