cyclic ordering
21MUSIC — This article is arranged according to the following outline: introduction written sources of direct and circumstantial evidence the material relics and iconography notated sources oral tradition archives and important collections of jewish music… …
22Arrow's impossibility theorem — In social choice theory, Arrow’s impossibility theorem, the General Possibility Theorem, or Arrow’s paradox, states that, when voters have three or more distinct alternatives (options), no voting system can convert the ranked preferences of… …
23Gloucestershire Old Spots — A Gloucestershire Old Spots boar Conservation status Rare breed Other names …
24Decomposition method (constraint satisfaction) — In constraint satisfaction, a decomposition method translates a constraint satisfaction problem into another constraint satisfaction problem that is binary and acyclic. Decomposition methods work by grouping variables into sets, and solving a… …
25PQ tree — A PQ tree is a tree based data structure that represents a family of permutations on a set of elements, discovered and named by Kellogg S. Booth and George S. Lueker in 1976. It is a rooted, labeled tree, in which each element is represented by… …
26Isomorphism — In abstract algebra, an isomorphism (Greek: ἴσος isos equal , and μορφή morphe shape ) is a bijective map f such that both f and its inverse f −1 are homomorphisms, i.e., structure preserving mappings.In the more general setting of category… …
27Cantor–Bernstein–Schroeder theorem — In set theory, the Cantor–Bernstein–Schroeder theorem, named after Georg Cantor, Felix Bernstein, and Ernst Schröder, states that, if there exist injective functions f : A → B and g : B → A between the sets A and B , then there exists a bijective …
28Graph coloring — A proper vertex coloring of the Petersen graph with 3 colors, the minimum number possible. In graph theory, graph coloring is a special case of graph labeling; it is an assignment of labels traditionally called colors to elements of a graph… …
29Hierarchy — A hierarchy (Greek: hierarchia (ἱεραρχία), from hierarches, leader of sacred rites ) is an arrangement of items (objects, names, values, categories, etc.) in which the items are represented as being above, below, or at the same level as one… …
30Rotation system — In combinatorial mathematics, rotation systems encode embeddings of graphs onto orientable surfaces, by describing the circular ordering of a graph s edges around each vertex.A more formal definition of a rotation system involves pairs of… …
