The designations on problems have the following meanings:

"(-)" = easier or shorter than most,

"(+)" = harder or longer than most,

"(!)" = particularly useful or instructive,

“(!)” = involves concepts marked optional in the text.

The exercise sections begin with easier problems to check understanding, ending with a line of dots. The remaining problems roughly follow the order of material in the text.

(-) Write down all possible adjacency matrices and incidence matrices for a 3-vertex path. Also write down an adjacency matrix for a path with six vertices and for a cycle with six vertices.