1

In projective geometry there is a duality principle between points and planes, i.e. every true statement yields a dual statement obtained by interchanging the the words "point" and "plane".

I am looking for a simple way of writing the corresponding statements side by side in two columns without having to align them manually; now and then there occur self-dual statements, which should therefore span the width of the page (not be columnized). I also want to enumerate the statements (one item for each pair of statements).

Here an example:

\documentclass{scrreprt}
        \usepackage{hyperref}
        \usepackage{enumerate}
        \usepackage{enumitem}
        \begin{document}
        \begin{enumerate}[label=P\arabic*]
            \item \label{itm: P1} There are two lines, which have no point and no plane in common
            \item \label{itm: P2} In every line lie at least three points and three planes.
            \item \label{itm: P3} Two distinct planes have one and only one line in common.
            \item \label{itm: P3'} Two distinct points have one and only one line in common.
            \item \label{itm: P4} Two lines have a point in common if and only if they have a plane in common.
       \end{enumerate}
       \end{document}

I want P3 and P3' to be placed side by side. I want to continue the list with interruptions for quite a bit, which is why I would prefer working with cross-references to doing it manually...

I would be grateful for suggestions!

closed as unclear what you're asking by Andrew Swann, Stefan Pinnow, CarLaTeX, TeXnician, Ruben Sep 12 '17 at 12:51

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • 2
    Do you mean something like what the tasks package provide? – user31729 Aug 4 '16 at 7:57
  • Yes, but I would like to have only one item for each double-statement, or what would be even better: the same item for both parts of a double-statement (e.g. a number) but an additional item to distinguish the two parts (e.g. "a)" on the left and "b)" on the right). – Larry Aug 4 '16 at 8:21
  • 2
    The \task! command is used for an item that spans all columns. For the ‘better’ way, are you looking for a macro which swaps ‘point’ and ‘plane’? – Bernard Aug 4 '16 at 11:33
  • I still have problems with referencing to a task... is that possible in tasks? I have added an example for what I am looking for. – Larry Aug 4 '16 at 21:28
  • 1
    Put P3 and P3' in a multicols environment – Peter Flynn Aug 4 '16 at 21:48