Passing optional data

The function 'mchrepfin' provides an example how different, only partially related data can be passed back by a function in CREP, besides the value of its call.

A completely separating algebra is of finite representation type if and only if for each vertex of the associated quiver the the attached partially ordered set of minimal chain sequences is of finite type as a poset. The function 'mchrepfin' uses this criterion to test for finite representation type of an algebra.

In case the algebra in question as been found not to be of finite type - as in our example -, there is a point 's' for which the corresponding poset 'p' is not of finite type. The arguments 's', 'p', and 'm' in the call of the function 'mchrepfin' in our example are used to pass these data back to the user - the argument 'p' containing the bare poset structure, 'm' information on the minimal chain sequences themselves. The other argument following contain even further information on the representation type of the poset 'p', which however we ignore in our example. All these arguments are optional. However, an argument not given can not be used to pass back any information.

The function 'mchrepfin' at work

As in our example it is already known from the results of the function 'wnn' - the Tits form having critical vectors -, that the algebra considered is not of finite type, we may assume, that the call of the function 'mchrepfin' originated in the interest for a non representation finite poset of chain sequences for the algebra.

Back to the worksheet of the example session.
Last modified: 04-03-1998