Hi,
On Sun, Nov 10, 2024 at 2:45 AM ntg-contextmailingli.expedited080---
via ntg-context <ntg-context@ntg.nl> wrote:
>
> I'm test driving luametatex. My needs usually extend to expressing formulas
> in TLA+ using nested display math formulas. Although I have suitable
> templates for doing this in Mark IV, I can't reproduce these satisfactorily
> in luametatex. For example, here's a formula from Leslie Lamport's 2006
> "Lower Bounds for Asynchronous Consensus":
>
> ~~~~~~~~~~~ transitive_reduction.tex ~~~~~~~~~~~~~
>
> \define\lbr {\lbrace \mkern 0.9mu}
> \define\rbr {{}\mkern 0.9mu \rbrace}
> \define\∀ {∀\mkern1mu}
> \define\∃ {∃\mkern2mu}
>
> \startdocument
>
> \startplaceformula
> \startformula [split=yes, align=flushleft, margin=standard,
> interlinespace=1ex]
> \bgroup \setupinterlinespace [line=1ex]
> \startalign [n=1, align={left,left}]
>
> \NC \text{\it TransitiveClosure}(R) ≜
> \NR
>
> \NC \quad
> \bgroup \setupinterlinespace [line=1ex]
> \startalign [n=2, align={left,left,left}, location=top]
>
> \NC \text{\sc let} \quad
> \NC \bgroup \setupinterlinespace [line=1ex]
> \startalign [n=1, align={left,left}, location=top]
>
> \NC \text{\it Dom} ≜ \lbr r[1]: r ∈ R \rbr
> \NR
>
> \NC \text{\it Rng} ≜ \lbr r[2]: r ∈ R \rbr
> \NR
>
> \NC \text{\it TC}[i ∈ ℕ] ≜
> \NR
>
> \NC \quad
> \bgroup \setupinterlinespace [line=1ex]
> \startalign [n=1, align={left,left}, location=top]
>
> \NC \text{\sc if}\ i = 0\
> \bgroup \setupinterlinespace [line=1ex]
> \startalign [n=2, align={left,left,left}, location=top]
>
> \NC \text{\sc then}\
> \NC R
> \NR
>
> \NC \text{\sc else}\
> \NC
> \bgroup \setupinterlinespace [line=1ex]
> \startalign [n=1, align={left,left}, location=top]
>
> \NC \lbr
> 〈d, e 〉∈ \text{\it Dom} × \text{\it Rng}:
> \NR
>
> \NC \quad \∃ c ∈ \text{\it Dom} ∩ \text{\it Rng}:
> \bgroup \setupinterlinespace [line=1ex]
> \startalign [n=1, align={left,left}, location=top]
>
> \NC ∧ 〈d, c〉∈ \text{\it TC}[i-1]
> \NR
>
> \NC ∧ 〈c, e〉∈ R \,\rbr
> \NR
> \stopalign \egroup
> \NR
> \stopalign \egroup
> \NR
> \stopalign \egroup
> \NR
> \stopalign \egroup
> \NR
> \stopalign \egroup
> \NR
>
> \NC \text{\sc in}\
> \NC \text{\sc union}\ \lbr \text{\it TC}[i] : i ∈ ℕ \rbr
> \NR
> \stopalign \egroup
> \NR
> \stopalign \egroup \stopformula \stopplaceformula
>
> \stopdocument
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> The command
>
> $ context --luatex transitive_reduction.tex
>
> produces the desired result, but
>
> $ context transitive_reduction.tex
>
> rejects the alignments and centers the lines instead. Can anyone suggest how
> I might adapt such nesting of alignments to luametatex?
>
I must admit that I don't know what is the expected output and if I
did break any of the rules or missed what you want, but the following
could hopefully work as a start for you:
\define\lbr {\lbrace \mkern 0.9mu}
\define\rbr {{}\mkern 0.9mu \rbrace}
\define\∀ {∀\mkern1mu}
\define\∃ {∃\mkern2mu}
\definemathsimplealign
[myalign]
[align=left,
location=top]
\definemathsimplealign
[myouteralign]
[align=left,
location=center]
\definemathsimplealign
[mydistancedalign]
[align=left,
distance=1em,
leftmargin=1em]
\definemathsimplealign
[mymarginedalign]
[align=left,
leftmargin=1em]
\startdocument
\startplaceformula
\startformula [align=flushleft]
\startmyouteralign
\NC \mathtextit{TransitiveClosure}(R) ≜
\NR
\NC
\startmydistancedalign
\NC \mtext{\sc let}
\NC
\startmyalign
\NC \mathtextit {Dom} ≜ \lbr r[1]: r ∈ R \rbr
\NR
\NC \mathtextit {Rng} ≜ \lbr r[2]: r ∈ R \rbr
\NR
\NC \mathtextit {TC\/}[i ∈ ℕ] ≜
\NR
\NC
\startmymarginedalign
\NC \text{\sc if } i = 0\
\startmyalign
\NC \text{\sc then}\
\NC R
\NR
\NC \text{\sc else}\
\NC
\startmyalign
\NC \lbr
〈d, e 〉 ∈ \text{\it Dom} × \text{\it Rng}:
\NR
\NC \quad \∃ c ∈ \text{\it Dom} ∩ \text{\it Rng}:
\startmyalign
\NC ∧ 〈d, c〉 ∈ \mathtextit {TC\/}[i-1]
\NR
\NC ∧ 〈c, e〉 ∈ R \rbr
\NR
\stopmyalign
\NR
\stopmyalign
\NR
\stopmyalign
\NR
\stopmymarginedalign
\NR
\stopmyalign
\NR
\NC \mtext{\sc in}
\NC \mtext{\sc union } \lbr \mathtextit {TC\/}[i] : i ∈ ℕ \rbr
\NR
\stopmydistancedalign
\NR
\stopmyouteralign
\stopformula \stopplaceformula
\stopdocument
/Mikael
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