Sarl3 - Sets and Relations Library

Sarl is a library designed to support formal concept analysis. Sarl3 is the third incarnation of the Sarl library. Sarl1 was first written in C, Sarl2 was written in Ocaml, and Sarl3 has been written in C with a Ruby interface.

Download

Currently the only version of Sarl3 is the content of the CVS repository. Checkout the module "sarl3", then change to the sarl3 directory, edit config.mak for your installation and run make.

Requirements include: gnome2-dev, gtk2-dev, gnome2-ruby, tcltk, ruby, g++

As the project becomes more mature it is intended to construct a debian package for Sarl3.

Examples

Following is an example to give a flavour of the library.

  require 'sarl'

  def create_bn_lattice(n)
    context = Context.new
    for g in 1..n do
      for m in 1..n do
        if g != m then
          context.insert(g,m)
        end
      end
    end
    return Lattice.new(context)
  end

The first thing to notice about this example is that objects and attributes are numbers. This is a central feature of the Sarl library. It operates over integers. Of course the integers have meanings which can be stored in a string table. However these meanings are only important for presentation, not calculation of the lattices so they do not play a large part in the library.

   require 'sarl'

   st = StringTable.new()
   st[1] = "one"
   st[2] = "two"

Let us now consider calculating the join irreducibles of a lattice.

  require 'sarl'

  # include the create_bn_lattice function given above

  lattice = create_bn_lattice(5)
  join_irr = BitSet.new()
  for c in lattice do
    if lattice.lower_covers[c].count == 1 then
      join_irr.set(c)
    end
  end

This shows that most relations look like arrays. In fact they are implemented internally as arrays and manifest themselves as such at the ruby layer.