set of defining relations
21Van Kampen diagram — In the mathematical area of geometric group theory, a van Kampen diagram is a planar diagram used to represent the fact that a particular word among the generators of a group given by a group presentation represents the identity element in that… …
22Grigorchuk group — In the mathematical area of group theory, the Grigorchuk group or the first Grigorchuk group is a finitely generated group constructed by Rostislav Grigorchuk that provided the first example of a finitely generated group of intermediate (that is …
23Free object — In mathematics, the idea of a free object is one of the basic concepts of abstract algebra. It is a part of universal algebra, in the sense that it relates to all types of algebraic structure (with finitary operations). It also has a clean… …
24WordNet — is a lexical database for the English language.[1] It groups English words into sets of synonyms called synsets, provides short, general definitions, and records the various semantic relations between these synonym sets. The purpose is twofold:… …
25sociology — sociologist, n. /soh see ol euh jee, soh shee /, n. the science or study of the origin, development, organization, and functioning of human society; the science of the fundamental laws of social relations, institutions, etc. [1835 45; < F… …
26List of first-order theories — In mathematical logic, a first order theory is given by a set of axioms in somelanguage. This entry lists some of the more common examples used in model theory and some of their properties. PreliminariesFor every natural mathematical structure… …
27Dirac equation — Quantum field theory (Feynman diagram) …
28Direct linear transformation — (DLT) is an algorithm which solves a set of variables from a set of similarity relations:   for where and are known vectors, denotes equality up to an unknown scalar multiplication, and …
29Bicyclic semigroup — In mathematics, the bicyclic semigroup is an algebraic object important for the structure theory of semigroups. Although it is in fact a monoid, it is usually referred to as simply a semigroup. The first published description of this object was… …
30Presentation of a group — In mathematics, one method of defining a group is by a presentation. One specifies a set S of generators so that every element of the group can be written as a product of some of these generators, and a set R of relations among those generators.… …
