Sstrhsrtj

In the statement of a mathematical lemma, I have two similar statements that are supposed to make up statement a) and b) of the lemma. However, since I want to align the similarities properly, after some fiddling around with makemathbox I have resorted to simply using alignedat-environments. So my current code looks like this:

For all

$begin{alignedat}[t]{2}

    t, t' & in c^+:text{with} & t & leq t'colon & ldots\

    r, r' & in c^-:text{with} & r & leq r'colon & ldots

end{alignedat}$

Edit: This is how I got so far, which is almost what I want:

documentclass{scrartcl}

usepackage{amsthm,amsmath,mathtools}

usepackage[inline]{enumitem}

setlist[enumerate]{

    label=textit{alph*}textup{)},

}

newtheorem{lemma}{Lemma}

begin{document}

        newlengthmyleftmarginsetlengthmyleftmarginleftmargin

        newlengthmyitemindentsetlengthmyitemindentitemindent

        begin{lemma}For all



        vspacepartopsep%

        noindenthspacemyleftmargin%

        begin{enumerate*}[mode=unboxed]%

            $begin{alignedat}[t]{4}

                makebox[myitemindent][r]{itemhspace{labelsep}}&&%

                t, t' & in c^+:text{with} & t & leq t'colon & 

                ldots

                \[dimexpritemsep+parseprelax]%

                %

                makebox[myitemindent][r]{itemhspace{labelsep}}&&%

                r, r' & in c^-:text{with} & r &leq r'colon &

                ldots

                \[dimexpritemsep+parseprelax]%

                %

                makebox[myitemindent][r]{itemhspace{labelsep}}&&%

                mathmakebox[widthof{$r, r'$}][l]{mathrm{S}}

            end{alignedat}$

            end{enumerate*}

        end{lemma}

        begin{proof}strut

        begin{enumerate}

            item Some argument;

            item Some argument.qedhere

        end{enumerate}

        end{proof}

end{document}

which produces

However, if you zoom in, you'll notice that the labels in the statement and the enumeration in the proof are not perfectly aligned. Also, you'll notice that the capital "S" are not aligned. How to do this right?

I'll use the original code, with a mocked up definition for im.

The alignment is possible, but the output is not really nice. The second realization is how I'd do it; I don't think that the alignment is helpful, but rather that it's distracting.

documentclass{article}

usepackage{amsmath}

usepackage{enumitem}



newtheorem{lemma}{Lemma}

newcommand{im}{I}



begin{document}



begin{lemma}

For all\[topsep]

$begin{alignedat}{4}

  makebox[leftmargini][r]{upshape(a)hspace{labelsep}}

  && t,t' &in c^+ &text{ with } t &leq t'textup{: }

  & V_{tt'}(im^pm_c V_t) &= im^pm_c V_{t'}textup{;}

  \

  makebox[labelwidth][r]{upshape(b)hspace{labelsep}}

  && r,r' &in c^- &text{ with } r &leq r'textup{: }

  & V_{rr'}(im^pm_c V_t) &subseteq im^pm_c V_{t'}.

end{alignedat}$

end{lemma}



begin{lemma}mbox{}

begin{enumerate}[label=upshape(alph*)]

item For all $t,t'in c^+$ with $tleq t'$textup{:}

      $V_{tt'}(im^pm_c V_t)=im^pm_c V_{t'}$textup{;}

item For all $r, r'in c^-$ with $rleq r'$textup{:}

      $V_{rr'}(im^pm_c V_t)subseteq im^pm_c V_{t'}$.

end{enumerate}

end{lemma}



end{document}

Finally, I found a solution myself: obstructions for proper spacing were:

1. That theorem-environments redefine all lengths involved in printing enumerations,


2. 
   alignedat introduces additional spacing.

The following code seems to do the correct thing, although I do not want why I need the additional length myspacewidth:

documentclass{scrartcl}

usepackage{amsthm,amsmath}

usepackage{printlen,array}

usepackage[inline]{enumitem}

setlist[enumerate]{%

    label=textit{alph*}textup{)}%

}

newtheorem{lemma}{Lemma}



newlengthmytopsepmytopseptopsep

newlengthmyleftmarginmyleftmarginleftmargin

newlengthmylabelsepmylabelseplabelsep

newlengthmyitemsepmyitemsepitemsep

newlengthmyparsepmyparsepparsep

newlengthmyspacewidth%

newenvironment{enumalign}[1]{%

    par%

    vspacemytopsep%

    noindent%

    letolditemitem%

    settowidthmyspacewidth{{} {}}%

    renewcommanditem{llap{strutolditemhspace{dimexprmylabelsep-myspacewidthrelax}}}%

    newcommandnl{\[dimexprmyitemsep+myparseprelax]}%

    begin{enumerate*}[mode=unboxed]$%

        begin{array}{@{hspace{myleftmargin}}r@{}*{#1}{r@{}>{{}}l@{ }}}%

}{%

        end{array}%

    $end{enumerate*}%

}

begin{document}

        begin{lemma}

        For all

            begin{enumalign}{3}

                item &

                t, t' & in c^+:text{with} & 

                t & leq t'colon & 

                a &= b

                nl%

                item & r, r' & in c^-:text{with} & r &leq r'colon &

            end{enumalign}

        end{lemma}

        begin{proof}strut

            begin{enumerate}

                item Some argument;

                item Some argument.

            end{enumerate}

        end{proof}

end{document}

which yields