Abstract
This paper proposes three models on additional relations to an organization structure which is a complete binary tree of height H; (i) a model of adding an edge between two nodes with a specific depth N, (ii) a model of adding edges between every pair of siblings with a specific depth N and (iii) a model of adding edges between every pair of nodes with a specific depth N. For each of three models, an optimal depth N^* is obtained by minimizing the total path length which is the sum of shortest path lengths between every pair of nodes.
