Re: LyX 2.5.2 regression: starred theorem environments have an empty heading

I have opened a ticket and can confirm the bug. If you put a normal 
Theorem BEFORE the Theorem*, then the problem goes away. But not if the 
Theorem comes AFTER the Theorem*. Weird.

https://www.lyx.org/trac/ticket/13356

Riki


On 8/19/26 1:25 AM, Rene Adad wrote:
>
> Hello,
>
> I have found a regression in LyX 2.5.2 affecting unnumbered (starred) 
> theorem environments.
>
> Steps to reproduce:
>
> 1.
>
>     Create a new document using the AMS Article class.
>
> 2.
>
>     Add the “Theorems (AMS)” module.
>
> 3.
>
>     Insert a paragraph using the “Theorem*” layout.
>
> 4.
>
>     Enter some text, for example: “This is a test.”
>
> 5.
>
>     View or export the document as PDF.
>
> Expected result:
>
> |Theorem. This is a test.|
>
> With French as the document language:
>
> |Théorème. Ceci est un test.|
>
> Actual result:
>
> |. This is a test.|
>
> Only the punctuation following the theorem heading is displayed. The 
> heading itself is missing.
>
> The generated LaTeX contains:
>
> |\providecommand\theoremname{} \theoremstyle{plain} 
> \newtheorem*{thm*}{\protect\theoremname}|
>
> Consequently, amsthm prints only the punctuation associated with the 
> empty theorem name.
>
> This appears to be a regression related to the fix for ticket #13307. 
> In LyX 2.5.1, |theorems-starred.inc| contained a language preamble 
> such as:
>
> |\providecommand{\theoremname}{_(Theorem)}|
>
> The LyX 2.5.2 change removed these explicit |LangPreamble| definitions 
> and now constructs theorem names from the layout information. However, 
> the starred theorem layouts do not appear to define a 
> |TheoremCrossRefName|. As a result, the generated fallback name is empty.
>
> Numbered theorem environments appear to be unaffected because their 
> layouts do define |TheoremCrossRefName|.
>
> The same problem is likely to affect the other starred environments, 
> such as |Lemma*|, |Proposition*|, |Corollary*|, and so on.
>
> A document-level workaround is:
>
> |\providecommand{\theoremname}{Theorem}|
>
> or, for a French document:
>
> |\providecommand{\theoremname}{Théorème}|
>
> Environment:
>
>  *
>
>     LyX 2.5.2
>
>  *
>
>     macOS
>
>  *
>
>     Official Qt 6 universal build
>
>  *
>
>     Reproduced with the “Theorems (AMS)” module and the |Theorem*| layout
>
> Could you please confirm whether this should be opened as a new 
> regression ticket?
>
> Best regards,
>
>
>

-- 
----------------------------
Richard Kimberly (Riki) Heck
Professor of Philosophy and Professor of Linguistics
Brown University

Pronouns: they/them/their
Website:http://rkheck.frege.org/

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