# Do journals that published a proof of an important theorem $T$ publish another proof of $T$?

I want to know whether or not a journal that published a proof $P$ of an important theorem $T$ is still open to accept another proof $P'$ of $T$ such that $P'$ is greatly simpler than $P$, assuming, of course, that $P'$ is correct.

• Sure, why not? It would depend on how important $T$ was and how much better or how illuminating the new proof was. I don't see why it would matter whether the old proof was published in the same journal or some other journal. – bof Aug 21 '14 at 8:11
• Do you have a simple proof of Fermat's Last Theorem? – bof Aug 21 '14 at 8:13
• @bof: Thanks for your attention. I am just being wary and discreet about choosing a journal. I have a simple proof of another of Fermat's theorem. We will see! – Megadeth Aug 21 '14 at 8:13
• It's less about $T$ than about $P'$, you might say: A substantially new proof may use different (new?) methods, from which we can possibly learn more than from $T$ itself. Also, $P'$ may be so differnt that it may suggest different generalizations of $T$. You might even publish a new(!) proof of Pythagoras, adding to an already long collection. – Hagen von Eitzen Aug 21 '14 at 8:20
• @bof: So did you imply that if $T$ is a conjecture then situation is different? – Megadeth Aug 21 '14 at 8:21

I guess it depends on many things. First of all, what is the relevance of $T$ in its field? And secondly: what is the relevance of the new proof of $T$?
Finally, more and more journals recommend to their referees that manuscripts should be original. A different proof of theorem $T$ will then be rejected almost immediately is the manuscript is written only to show that you found another proof.