Before a single wall gets drawn, someone has to decide which rooms sit next to each other and which ones need to be kept apart. That decision-making process uses two tools you'll encounter constantly on the ARE: adjacency matrices and relationship diagrams.

An adjacency matrix is a grid. Program spaces line both axes. Each cell in the grid rates the relationship between two spaces, typically on a scale from "must be adjacent" to "must be separated." It's systematic, it's objective, and it forces you to think about every possible pair of spaces in the program.

A relationship diagram takes that same information and makes it visual. Bubble diagrams, for example, represent spaces as circles scaled to relative area, connected by lines whose thickness or style indicates how strong the relationship is. Stacking diagrams do something similar but vertically, showing which departments belong on which floors and how they connect across levels.

These tools sit at the heart of Objective 4.4 because spatial organization is never random. A hospital emergency department needs direct access to imaging and surgery. A courthouse requires separated circulation paths for the public, judges, and defendants in custody. A school needs the gymnasium near the cafeteria but away from quiet classrooms. The matrix captures these requirements; the diagram communicates them.

For the ARE, you need to both create these tools from program data and interpret existing ones to evaluate whether a proposed layout satisfies the program requirements.