This part is dedicated to "basic algorithms". The notion "basic algorithm" is quite artificial. However, it is used here to differentiate from algorithms applying numerical or number-theoretical methods.
As such, a basic algorithm in terms of this part of BookOfProofs will be any algorithm dealing with searching, hashing, sorting, matching, traversing graphs, finding graphs, rather then with solving numerical problems.
Another distinction used here to distinguish a "basic algorithm" from other types of algorithms will be that the objects they operate on are data-structures rather than mathematical objects like numbers or equations.