(mathematics) A branch of topology dealing with knots.

(mathematics) A mathematical theory that models a cluster structure in a random graph to describe the spread of phenomena passing through the edges.

(mathematics, economics) A branch of applied mathematics that studies strategic situations in which individuals or organisations choose various actions in an attempt to maximize their returns.

(mathematics) The mathematical study of probability (the likelihood of occurrence of random events in order to predict the behavior of defined systems).

Used other than figuratively or idiomatically: see group, theory; a theory about (particular kinds of) groups.

(physics) A supposed theory uniting all fundamental physical phenomena into a single framework.

(mathematics) The mathematical theory of sets. / (music) Musical set theory, a systematic approach to describing musical objects and their relationships.

(uncountable, mathematics) The branch of mathematics dealing with the properties of graphs (networks of vertices and edges).

(sociology) Any of various models of group behavior (such as economic behavior, criminal behavior, or consumer behavior) as the cumulative result of rational choices made by individuals expressing on their preferences and/or meeting their needs.

Any theory attempting to explain the process by which individuals explain the causes of behaviour and events.