  The paper addresses design/building frameworks for some kinds of tree-like
and hierarchical structures of systems. The following approaches are examined:
(1) expert-based procedures, (2) hierarchical clustering; (3) spanning problems
(e.g., minimum spanning tree, minimum Steiner tree, maximum leaf spanning tree
problem; (4) design of organizational 'optimal' hierarchies; (5) design of
multi-layer (e.g., three-layer) k-connected network; (6) modification of
hierarchies or networks: (i) modification of tree via condensing of neighbor
nodes, (ii) hotlink assignment, (iii) transformation of tree into Steiner tree,
(iv) restructuring as modification of an initial structural solution into a
solution that is the most close to a goal solution while taking into account a
cost of the modification. Combinatorial optimization problems are considered as
basic ones (e.g., classification, knapsack problem, multiple choice problem,
assignment problem). Some numerical examples illustrate the suggested problems
and solving frameworks.
