Generic doubly linked lists.
bool partial_order_needed_
indicate whether a new partial ordering is necessary for the elimination
const List< NodeSet > * subsets_
the subsets constituting the partial ordering
const List< NodeSet > * partialOrder() const noexcept
returns the current partial ordering
bool isPartialOrderNeeded() const noexcept
indicates if a new partial ordering is needed
gum is the global namespace for all aGrUM entities