returns one of the orders of the nodes such as the parents of any
node are less ranked than it when is.null(ord). If not check
that the proposed order is either a right permutation
(is.numeric(ord)) or a vector of node names providing a
topological order (is.character(ord)).
Usage
order4nbn(nbn, ord=NULL)
Value
a permutation vector of the nodes of the /nbn/ or a named list with
the nodes not having their parents before them.
Arguments
nbn
nbn object for which the order must be computed.
ord
NULL or an order to test as a permutation or a
vector of names.
Details
When !is.null(ord) the order must be an order, if not an error
is issued.