Combinatorics

Combinatorial algorithms deal with the arrangement of objects in cells. The number of such algorithms is legion due to such considerations as : are the objects ordered within cells; are the cells themselves ordered; are empty cells allowed; how many kinds of distinguishable objects are present. The whole range of such algorithms would fill a book in its own right — a few of the most basic ones are given here covering permutations (with derangements as a subset), combinations, selections with repetition, compositions and partitions.