On Fri, 1 Jun 2001, Fergus Henderson wrote:

Sorry for the off-topic post, but I figured someone here would know... can anyone please tell me how to do the double-square-bracket symbols that are often used in denotational semantics in LaTex? It's like "[[" but a single symbol without the space between the two brackets. (I checked the Latex companion, but it's not listed there AFAICT.)

It's either $[\![$ or $[\!\![$; likewise for close brackets. It's just very crude as \! means `insert standard-width negative math-space here'. ___cheers,_dave________________________________________________________ www.cs.bris.ac.uk/~tweed/pi.htm|tweed's law: however many computers email: tweed@cs.bris.ac.uk | you have, half your time is spent work tel: (0117) 954-5250 | waiting for compilations to finish.

Joe English wrote:

Fergus Henderson wrote:

...

Sorry for the off-topic post, but I figured someone here would know... can anyone please tell me how to do the double-square-bracket symbols that are often used in denotational semantics in LaTex? It's like "[[" but a single symbol without the space between the two brackets.

It's often done by squishing together two ordinary square brackets with a negative thin space (\!):

\newcommand{\sembrack}[1]{[\![#1]\!}

This looks good with Computer Modern; with other fonts YMMV.

There's also \llbracket and \rrbracket, from stmaryrd. They look better than the negative space hack, IMHO (now all I need is for Alan Jeffrey to write in and say that \{ll,rr}bracket are implemented with the negative space hack :-) Cheers, Andy -- Andy Moran Ph. (503) 526 3472 Galois Connections, Inc. Fax. (503) 350 0833 3875 SW Hall Blvd. http://www.galconn.com Beaverton, OR 97005 moran@galconn.com

On Fri, Jun 01, 2001 at 12:41:05PM -0400, Ken Shan wrote:

On 2001-06-01T08:41:34-0700, Andrew Moran wrote:

...

There's also \llbracket and \rrbracket, from stmaryrd. They look better than the negative space hack, IMHO (now all I need is for Alan Jeffrey to write in and say that \{ll,rr}bracket are implemented with the negative space hack :-)

Heh. Actually they're not (and cannot, because they are extensible delimiters -- useful for typesetting the denotation of multiple-line programs!).

Here's a negative space hack that gives extensible brackets: write \Sem{expr} to wrap an expression. (Doubtless someone who knows TeX could do better.) \newsavebox{\sembox} \newlength{\semwidth} \newlength{\boxwidth} \newcommand{\Sem}[1]{% \sbox{\sembox}{\ensuremath{#1}}% \settowidth{\semwidth}{\usebox{\sembox}}% \sbox{\sembox}{\ensuremath{\left[\usebox{\sembox}\right]}}% \settowidth{\boxwidth}{\usebox{\sembox}}% \addtolength{\boxwidth}{-\semwidth}% \left[\hspace{-0.3\boxwidth}% \usebox{\sembox}% \hspace{-0.3\boxwidth}\right]% }