#LyX file created by tex2lyx 2.3
\lyxformat 544
\begin_document
\begin_header
\save_transient_properties true
\origin roundtrip
\textclass amsart
\begin_preamble
\usepackage{babel}

\end_preamble
\use_default_options false
\begin_modules
theorems-ams
\end_modules
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\language english
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\index Index
\shortcut idx
\color #008000
\end_index
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\end_header

\begin_body

\begin_layout Standard
This is a dummy file
\end_layout

\begin_layout Standard
It has a theorem, a lemma and a proof.
\end_layout

\begin_layout Standard
The theorem is recognized is a style provided by the module theorems-ams, since the preamble code matches.
\end_layout

\begin_layout Standard
The lemma is not recognized as a command provided by a module, since the preamble code is from an older version of LyX, and modules are only loaded if the preamble code matches (otherwise you could easily get completely different output for some often used names like 
\backslash
theorem.
\end_layout

\begin_layout Standard
The proof is recognized as a builtin style provided by the text class.
\end_layout

\begin_layout Lemma
this is a lemma
\end_layout

\begin_layout Theorem
this is the theorem
\end_layout

\begin_layout Proof
this is the proof 
\end_layout

\end_body
\end_document
