Non-Commutative Squares

Non-Commutative Squares (NCSq) is a SATySFi package for drawing rectangular diagrams.

Features

• Draw a rectangular diagram by specifying a matrix of cells. The layout of the source code is closed to the intended diagram.
• Arrows automatically stretch to match long labels and large objects.
• A variety of styles of arrow head, tail and body in arbitrary combination.
• Parallel arrows.

Install

Using Satyrographos:

$ opam install satysfi-ncsq
$ opam install satysfi-ncsq-doc # for documentation
$ satyrographos install

Usage

In preamble:

@require: ncsq/ncsq

The NCSq module provides a block command +cd, an inline command \cd, and a math command \cd-m. All of them receive a rectangular array of cells and draw a diagram.

+NCSq.cd(open NCSq in [
  [object ${A}; arrow ?:${f} right; object ${B}];
  [arrow ?*?:${g} down; empty; arrow ?:${h} down];
  [object ${C}; arrow ?*?:${k} right; object ${D}];
]);

For such a simple diagram, a helper package ncsq/easy-cd provides simpler syntax.

+EasyCD.cd[
  ${| A | f | B |};
  ${| g |   | h |};
  ${| C | k | D |};
];

See docs/ncsq-example.saty for details and further examples.

Related packages

• The standard library of SATySFi includes cd package.
• Our package is similar to Paul Taylor's diagrams TeX package in syntax (rectangular array of cells) and functionality (automatic arrow stretching).