FUNCTION: tau - Auslander-Reiten-shift on K₀X

CALLING SEQUENCE:
tau(f)

PARAMETERS:
f - an arbitrary class of type quiver

SYNOPSIS:

• Computes the Auslander-Reiten shift of any object in K₀X of type "quiver".

EXAMPLES:

> with(tubular):

> read_in(3,3,3);

assume f1 defined

> show(f1);

> f2 := tau(f1); show(f2);