FUNCTION: preprojposet - compute the beginning of the postprojective component for a poset

CALLING SEQUENCE:
preprojposet(p)

PARAMETERS:
p - a poset

SYNOPSIS:

• preprojposet passes the poset p to an external program, that then tries to compute the beginning of a preprojective component of the Auslander Reiten quiver of p.
  
  First the program asks, whether you wish to see the dimension vectors (enter 'd') or the coordinate vectors (enter 'c') of the representations.
  
  You next may take influence on the way, the Auslander Reiten quiver is printed in output. The orbits of the Auslander Reiten are printed in columns, one column for each orbit.
  If you answer the question 'Permutation (y/n) ?' with 'y', you are asked to specify the order in which the orbits are arranged.

• Output of the program is to a file called preprojposet.res (or preprojp.res) in the CREP home directory. (This is the directory Maple has to be invoked from for use of CREP.)

• All dialog will happen in the environment, Maple was called from. So make sure, your current Maple session is not running in the background, when invoking preprojposet from Maple.

• The program preprojposet can also be invoked from the CREP home directory without using maple. In this case, the program also prompts for interactive input of the poset p.

EXAMPLES:

> a:=[4, [[1, 2, 3, 4]]];

> preprojposet(a);

compute coordinate vectors (c)
or dimension vectors (d) ?
d
Permutation (y/n) ?
y
0 1 2 3 4
3 0 2 1 4