FUNCTION: pswild - test a poset for wild representation type

CALLING SEQUENCE:
pswild(p)
pswild(p,c,incl,img)

PARAMETERS:
p - a poset
c, incl, img - optional arguments evaluating to names

SYNOPSIS:

• pswild tests, whether the poset p is of wild representation type.

• Testing is done by looking for hypercritical subposets of p. (Criterion of Nazarowa)

• If the poset is of wild representation type, various data will be returned via the optional arguments. In particular:
  • c - will give the name of the hypercritical subposet of p found by the function.

  • incl - a list containing data about the inclusion c --> p found by the function. In fact incl[i] is the image in p of the point i of c under this inclusion.

  • img - a vector marking the points of p belonging to the image of c by 1, those not belonging to the image by 0.

EXAMPLES:

> p:=[8,{[1, 4, 8], [6, 7], [3, 2], [2, 5, 6]}];

> pswild(p,'c','incl','img');

> print(c);

> print(incl);

> print(img);