FUNCTION: heralg[cartan_matrix] - the Cartan matrix of a quiver algebra

CALLING SEQUENCE:
cartan_matrix(Q)

PARAMETERS:
Q - a quiver given by a quiverdata structur

SYNOPSIS:

• The function cartan_matrix(Q) computes the Cartan matrix of the path algebra of the quiver Q. The columns of the Cartan matrix are the dimension vectors of the indecomposable projective modules.

• This function is part of the heralg package, and so can be used in the form cartan_matrix(..) only after performing the command with(heralg) or with(heralg, cartan_matrix). The function can always be accessed in the long form heralg[cartan_matrix](..).

EXAMPLES:

> with(heralg):

> cartan_matrix( [2,[[1,2,r]]] );

> Q := [ 3, [[1,2], [2,3,2]]];

> cartan_matrix(Q);