I am trying to number my theorems as follows:

Theorem 1.A. First part of a theorem.

Theorem 1.B. Second part of the theorem.

Theorem 2. A theorem with no parts.

The following almost works:


But it does not increment the theorem counter as I want, so that

\begin{theorempart}First part of a theorem.

\begin{theorempart}Second part of the theorem.

\begin{theorem}A theorem with no parts.


Theorem 0.1. First part of a theorem.

Theorem 0.2. Second part of the theorem.

Theorem 1. A theorem with no parts.

Also, I don't know how to get the part-number to be a letter instead of a number.

I am using MiKTeX.


The model I used is that of the subequations environment in amsmath:


  \protected@edef\theparentnumber{\csname the#1\endcsname}%
  \expandafter\def\csname the#1\endcsname{\theparentnumber.\Alph{#1}}%




Two, first part

Two, second part


\ref{thm:one}, \ref{thm:two}, \ref{thm:twoA}, \ref{thm:twoB}, \ref{thm:three}.


You enclose the part in which the theorems have to be "subnumbered" in the subtheorem environment, which takes as argument the name of the theorem-like environment you want to affect.

The \label commands are not mandatory, but you can see that you can also set a "global" label for the subnumbered theorem.

  • @egreg This is great, but somehow the hyperlinks generated with \cref{} no longer work. I generated Theorems 5.A and 5.B like this, but any link to 5.A jumps to Theorem 1 and any link to 5.B jumps to Theorem 2. Any idea how to fix that?
    – mimuller
    Nov 1 '15 at 4:44
  • 1
    @ItsmeMimi This warrants a new question.
    – egreg
    Nov 1 '15 at 9:17
  • 1
    @egreg Done: tex.stackexchange.com/questions/276238/…. Thanks for the code though, this already helped me a lot!
    – mimuller
    Nov 2 '15 at 18:11
  • While this is great (and I've already given it a +1 from a past visit), I feel this issue with the false anchors should be made clearer. I had put this code into my preamble, not having really read the comments. I was then having this issue, and coming back to this question saw that I wasn't the first. It's perhaps worth noting at the top of the answer that the referencing doesn't work as some would like, but that it was fixed (with only a very minor change) in the question linked by @ItsmeMini. As always egreg, thanks for the extremely useful code! :)
    – Sam OT
    Jul 23 '18 at 18:17

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