Fig. 4

Illustration of an expander graph with d=2 and c=3. Following coding theory terminology, we call the left variables nodes (there are N such variables), which correspond to the entries of x_t, and the right variables parity check nodes (there are M such nodes), which correspond to entries of y_t. In a bipartite graph, connections between the variable nodes are not allowed. The adjacency matrix of the bipartite graph corresponds to our A or A_t