[OS X TeX] Exercises

Sat Apr 18 15:48:56 EDT 2009

Michael,

What is odd that exercises are numbered with the section number, as  
1.1, 1.2, etc. Normally, what is displayed is what is stored. Not in  
this  case, of Exercise 1.2 \ref only remembers 2.

In Section 4, everything is consecutively numbered: Corollary 4.6,  
Theorem 4.7, etc., so that they be easily found. A typical section has  
30-40 exercises; it would look funny to have them numbered along with  
everything else.

I do not understand how the Exercises are properly numbered. How do  
they know the section number? How is it lost with \ref?

GG

On 18-Apr-09, at 2:22 PM, Michael Sharpe wrote:

> George,
>
> I believe that what you are seeing here is the normal behavior of  
> \label for an item in an enumeration---it stores the current value  
> of the counter \enumi and the current page number in the .aux, but  
> not the section number. Here are a couple of suggestions you might  
> investigate.
>
> 1. You can add the page number to the reference, with something like
>
> \newcommand{\exerref}[1]{Exercise \ref{#1} (p.\pageref{#1})}
>
> then write, for example
>
> \item Let the binary relation $ < $ satisfy the conditions of  
> \exerref{Exer:I.1.1}.\label{Exer:I.1.2}
>
> 2. I prefer to do exercise numbering as part of the equation  
> enumeration, along with theorems, lemmas, propositions, remarks,  
> definitions, so that everything I want numbered gets a unique  
> sequential id, and \label stores the entire id. That may not be to  
> everyone's taste, but I really dislike separate numbering sequences,  
> which makes it difficult to find, say, Theorem 2.3, when it comes  
> after Proposition 2.245.
>
> By the way, \subsubsection*{Orders} should not be within the  
> exercises---it will be ignored.
>
> Best,
>
> Michael
>
> On Apr 18, 2009, at 10:07 AM, George Gratzer wrote:
>
>> Michael,
>>
>> More trouble in paradise...
>>
>> I am now using your exercises environment, it displays with  
>> perfection.
>>
>> But.
>>
>> Sample code (short):
>>
>> \begin{exercises}
>>
>> \subsubsection*{Orders}
>>
>> \item Define $x < y$ to mean \dots label{Exer:I.1.1}
>>
>> \item Let the binary relation $ < $ satisfy the conditions of  
>> Exercise~\ref{Exer:I.1.1}.\label{Exer:I.1.2}
>> \end{exercises}
>>
>> These two exercises are numbered "1.1" and "1.2", as they should  
>> be, they are the first two exercises in Section 1. But \ref{Exer:I. 
>> 1.1} produces "1", not "1.1".
>>
>> I do not understand.
>>
>>
>> GG
>>
>>
>> On 16-Apr-09, at 5:29 PM, Michael Sharpe wrote:
>>
>>> To allow more space for the exercise number and section number,  
>>> you may wish to change the exercises macro so it reads something  
>>> like
>>>
>>> \newenvironment{exercises}
>>>  {
>>>  \begin{xcb}{}\noindent\textbf{Exercises}
>>> \settowidth{\leftmargini}{NNNN.\hskip\labelsep}
>>>  \begin{enumerate}
>>> \let\olditem\item
>>> \def\staritem{\let\exerstar\par\olditem }
>>> \renewcommand{\item}{\let\exerstar\empty\olditem }
>>> \renewcommand{\labelenumi}{\ifx\exerstar\empty\else*\fi\thesection. 
>>> \theenumi.}
>>> }
>>> {\end{enumerate}\end{xcb}}
>>>
>>> Note that the \settowidth line was moved to just above  
>>> \begin{enumerate}.
>>>
>>> Michael
>>>
>>> On Apr 16, 2009, at 2:26 PM, George Gratzer wrote:
>>>
>>>> And one more question. What do I need to do so that the number of  
>>>> the exercise is of the form 4.5, where 4 is the section number.
>>>>
>>>> I could do this if I knew the name of the counter...
>>>>
>>>> GG
>>>>
>>>>
>>>> On 16-Apr-09, at 4:14 PM, George Gratzer wrote:
>>>>
>>>>> You are right, the * should come before the number (for  
>>>>> alignment). How do i do that/
>>>>>
>>>>> GG
>>>>>
>>>>> On 10-Apr-09, at 1:33 PM, Michael Sharpe wrote:
>>>>>
>>>>>>
>>>>>> On Apr 10, 2009, at 9:56 AM, George Gratzer wrote:
>>>>>>
>>>>>>> In my new book, I have exercises at the end of each section. I  
>>>>>>> use the xcb environment from amsbook.cls:
>>>>>>>
>>>>>>> \newenvironment{xcb}{%
>>>>>>> \setcounter{enumi}{0}%
>>>>>>> \settowidth{\leftmargini}{\labelenumi\hskip\labelsep}%
>>>>>>> \setcounter{enumii}{4}% letter d
>>>>>>> \settowidth{\leftmarginii}{\labelenumii\hskip\labelsep}%
>>>>>>> \@startsection{section}% counter name; ignored because of the
>>>>>>>                          % * below
>>>>>>> {1}% sectioning level
>>>>>>> {\z@}% indent to the left of the section title
>>>>>>> {18\p@\@plus2\p@}% vertical space above
>>>>>>> {1sp}% Space below of 13pt base-to-base, so none needs to be  
>>>>>>> added
>>>>>>> % here; but \z@ would cause the following text to be run-in,  
>>>>>>> so we
>>>>>>> % use 1sp instead.
>>>>>>> {\bfseries}% The font of the subsection title
>>>>>>> *% always unnumbered
>>>>>>> }{%
>>>>>>> \par
>>>>>>> }
>>>>>>>
>>>>>>>
>>>>>>> modified as follows:
>>>>>>>
>>>>>>> \newenvironment{exercises}
>>>>>>> {
>>>>>>> \begin{xcb}{}\noindent\textbf{Exercises}
>>>>>>> \begin{enumerate}
>>>>>>> \renewcommand{\labelenumi}{\theenumi.}
>>>>>>> \settowidth{\leftmargini}{NN.\hskip\labelsep}
>>>>>>> }
>>>>>>> {\end{enumerate}\end{xcb}}
>>>>>>>
>>>>>>> and then
>>>>>>>
>>>>>>> \begin{exercises}
>>>>>>>
>>>>>>> \item
>>>>>>>
>>>>>>> \begin{exercises}
>>>>>>>
>>>>>>> works well.
>>>>>>>
>>>>>>> Problem: I want the difficult exercises marked with a *:
>>>>>>>
>>>>>>> 25*.
>>>>>>>
>>>>>>> How could I do that? How do I modify one number, without  
>>>>>>> effecting the rest?
>>>>>>>
>>>>>>
>>>>>> One way is to redefine the exercises environment as follows.
>>>>>>
>>>>>> \newenvironment{exercises}
>>>>>> {
>>>>>> \begin{xcb}{}\noindent\textbf{Exercises}
>>>>>> \begin{enumerate}
>>>>>> \let\olditem\item
>>>>>> \def\staritem{\let\exerstar\par\olditem }
>>>>>> \renewcommand{\item}{\let\exerstar\empty\olditem }
>>>>>> \renewcommand{\labelenumi}{\theenumi\ifx\exerstar\empty\else* 
>>>>>> \fi.}
>>>>>> \settowidth{\leftmargini}{NN.\hskip\labelsep}
>>>>>> }
>>>>>> {\end{enumerate}\end{xcb}}
>>>>>>
>>>>>> You might want to change the alignment of the numbers, or  
>>>>>> perhaps place the * before the exercise number---that's a  
>>>>>> simple change.
>>>>>>
>>>>>> Michael
>>>>>>
>>>>>> ----------- Please Consult the Following Before Posting  
>>>>>> -----------
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>>>>>>
>>>>>
>>>>> ----------- Please Consult the Following Before Posting  
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>>>>>
>>>>
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>>>
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>>
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>>
>
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