I am using a book style file and in the preamble I defined some theorem environment. But in the Definition and Lemma part I want nonitalic content. Please suggest. My preamble are

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    After so many years being a user of TeX.SE you have neither learned of a MWE nor how to format posts :-( And you mean book class file, most likely)
    – user31729
    Jun 15 '17 at 7:09
  • Mr. Christian Hupfer ! Sorry I am not an expert of TeX like you, so I am asking for help. Jun 15 '17 at 9:43

Below suggestion is not good but it works...


  • Yes, it works - no it is not good style. Much better is to use the amsthm package. Jun 15 '17 at 7:40
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    \rm has been obsolete and deprecated for more than 20 years.
    – egreg
    Jun 15 '17 at 8:04
  • Dear Andrew Swann ! As you suggested above, both are not working. When I am using amsthm then it is giving error already defined. Jun 15 '17 at 9:40

You can use the ntheorem package:

  \begin{tm}It happens that $2+2=4$\end{tm}
  \begin{lm}Why not?\end{lm}
  • Dear Sir ! This ntheorem is also not working. Actually, I am using a class file of a book given by the publisher. Jun 16 '17 at 5:19
  • @DeepeshPatel Can you please explain in which way it is not working? Jun 16 '17 at 6:16

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