X-VM-v5-Data: ([nil nil nil nil nil nil nil t nil] [nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil]) Date: Wed, 21 Mar 90 10:20:09 CET Reply-To: LaTeX-L Mailing list Sender: LaTeX-L Mailing list From: PZF5HZ@RUIPC1E.bitnet To: Rainer Schoepf Status: R X-Status: X-Keywords: X-UID: 57 During my time at the University Mainz I spent a long time thinking about a proper interface to include a generic theorem environment into LaTeX which is both suitable for the author and for the publisher. The result of this work was described in TUGboat 10#3 I think. I do not believe that a level scheme as proposed by Michael would be flexible enough to handle even the standard cases. On the other hand inside one document one will normally only need a few different layout. Here are some comments to Michaels notes: ..... At the AMS one recent innovation from the editors that gave us some headaches was to require that if a proof followed immediately after a theorem the intervening space would be less than if the proof followed something else (perhaps a remark, say): \smallskipamount instead of \medskipamount. Other than having a few different levels, the flexibility that I would like to see added to theorem-type environments is as follows: 1. Allow theorem-type environments to be unnumbered, either individual instances, or all instances of a given class (e.g., corollary, proof, or remark). The numbering scheme can adjusted easily by the standard \newtheorem (for all instances of a class), for individual instances one can propose a scheme where \newtheorem{remark}... defines both a `remark' and a `remark*' environment. 2. Allow a name to be used instead of a number: ``Disjunctivization Theorem'' instead of ``Theorem 3.2''. This is probably the most critical issue, at the moment I have no idea for a suitable syntax. 3. Allow the numbering to be modified in individual cases---for example: Definition 2.1' in addition to Definition 2.1, or Theorems A and B at the beginning of a paper with all the other theorems numbered in the usual way. This could probably be done as a special case of item 2. Logically Definition 2.1' is a subdefinition of Definition 2.1. Therefore it should be defined by something like \newtheorem{Def}{Definition}:section| \newtheorem{SubDef}{Definition}:Def| \renewcommand{\theSubDef}{\theDef\alph{SubDef}} The declarations above would produce 2.1a but ' could be provided in a similar way. Drawback: Such a scheme would work only on the most recent Definition. To get some sort of backreference one would need a different scheme. But, and that's the main point, we first have to make clear what are the logical concepts behind the layout and then try to define a syntax 4. Allow the user to suppress the parentheses supplied automatically around the optional argument of \begin{theorem}. Or some other way to add something such as a \cite and not get parentheses---our editorial department would like to see ... If this is a general decision (and I suppose it is) then there is no problem in the current LaTeX or the style option I wrote. Simply redefine \@beginopargtheorem in your style file or write some new \theoremstyles for my option. I have one more comment about what seems to be a slightly more general issue. When I started thinking about the enunciation question, I went through some sample (non-LaTeX) papers from our publications and found some unusual numbering schemes that I wouldn't know how to do in the current LaTeX. The most interesting scheme had theorems and other enunciations numbered along with subsections. Here is a sectioning skeleton lifted from a paper that appeared in August 1988, with irrelevant information removed. (If you classify examples, proofs, and remarks as enunciations, then there are practically no non-enunciation subsections here.) This can be easily done in the LaTeX 2.9, or am I missing something? \newtheorem{theorem}{Theorem}:section| \newtheorem{remark}:theorem|{Remark} \newtheorem{example}:theorem|{Example} ... and so on. While this kind of scheme is rare, it is not idiosyncratic to one or two authors. In two issues pulled at random from our library three articles (out of 39 total) used such a scheme. From past experience that's pretty much what I expected. In extreme cases some authors even have the displayed equations numbered consecutively with everything else. In the example that I looked at, the author put parentheses around the numbers for theorems and subsections so that they had the same form as the equation numbers. This is clearly a design decision and a style file could easily handle such a layout. It is not a question for the user! Contrary to the LATeX users, the AMS TEX users tend to format much too much their documents. Since they have to add their numbers (for example) by hand the step further to add some () around them is easily done. In LATeX the numbers will be generated automaticly and the layout will be fixed by the style so that a user might complain about not being able to put () around something or leave them out, but he or she will not make the foolish mistake to insert them manually. I don't want to say that this is not a possible layout (even if I would not like it) the mistake is to put this layout decision into the document instead in the style definition. The chief difficulty of using such a scheme in LaTeX is getting the number of a theorem to appear to the left of the word ``Theorem'' instead of to the right; currently in LaTeX the ordinary user can't get ... This is handled properly in my style option. ... \section{}\begin{theorem} but I'm not sure how this part ought to look. As Leslie pointed out, this is clearly not the way one should those things logically. And the important thing is that the document should reflect the logical structure of its contents. Conclusion: The way LaTeX handles theorem-like environments is basically okay. The user is able to declare certain logical units and reserve some specific layout for them. These declarations are at the beginning of a document so that they could easily changed by a publisher. My style option provides further control by allowing things like \theoremstyle to define a (more or less) arbitary layout. For certain math journal article styles (like the mentioned amsart) it might be advisable to predefine certain structures or add a few more \theoremstyles. What is missing is in my opinion a proper syntax to handle special cases which require a special heading of some sort (like 2.1') or (blabla Theorem) but follow in other respects the layout convention of a special class. Final remark: I think that Proofs are not a special class of the theorem-like meta class. In my opinion to many thinks have to be handled differently so that I would like to add a proof theorem with its own logical concepts (like \proofsteps etc.).