Mastering Complexity

19

Tearing Circuits

19.1 INTRODUCTION

When partitioning identifies blocks, each can be subjected to a second level of analysis we call tearing. We use tearing to topologically order blocks internally.

We tear circuits because they violate topological order. Tearing orders marks in a DSM spreadsheet so when the DSM spreadsheet is repartitioned, only general marks (x) remain below the diagonal, as shown in Figure 19.1.

Although a DSM spreadsheet is more compact and easier to work with, to understand tearing we choose to describe it in terms of its equivalent graph. In this graph, a directed arc between nodes is represented within DSM spreadsheets by elements having predecessors’ marks in their rows. Removing an arc in the graph corresponds ...