DerangementQ[p] tests whether permutation p is a derangement, that is, a permutation without a fixed point.

Diameter[g] gives the diameter of graph g, the maximum length, among all pairs of vertices in g, of a shortest path between each pair.

DihedralGroupIndex[n, x] returns the cycle index of the dihedral group on n symbols, expressed as a polynomial in x[1], x[2], ..., x[n].

DihedralGroup[n] returns the dihedral group on n symbols. Note that the order of this group is 2 n.

Dihedral is an argument to the Polya-theoretic functions ListNecklaces, NumberOfNecklaces, and NecklacePolynomial, which count or enumerate distinct necklaces. Dihedral ...

Distances[g, v] returns the distances in nondecreasing order from vertex v to all vertices in g, treating g as an unweighted graph.

DistinctPermutations[l] gives all permutations of the multiset described by list l.

DominatingIntegerPartitionQ[a, b] yields True if integer partition a dominates integer partition b, that is, the sum of a size-t prefix of a is no smaller than the sum of a ...

DurfeeSquare[p] gives the number of rows involved in the Durfee square of partition p, the side of the largest-sized square contained within the Ferrers diagram of p.

Eccentricity[g] gives the eccentricity of each vertex v of graph g, the maximum length among all shortest paths from v.