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The term regular can mean normal or in accordance with rules. It may refer to:





There is an extremely large number of unrelated notions of "regularity" in mathematics.

Algebra and number theory[edit]

(See also the geometry section for notions related to algebraic geometry.)


Combinatorics, discrete math, and mathematical computer science[edit]


Logic, set theory, and foundations[edit]

Probability and statistics[edit]

  • Regular conditional probability, a concept that has developed to overcome certain difficulties in formally defining conditional probabilities for continuous probability distributions
  • Regular stochastic matrix, a stochastic matrix such that all the entries of some power of the matrix are positive


  • Regular (or ) space, a topological space in which a point and a closed set can be separated by neighborhoods
  • Regular homotopy
  • Free regular set, a subset of a topological space that is acted upon disjointly under a given group action
  • Regular isotopy in knot theory, the equivalence relation of link diagrams that is generated by using the 2nd and 3rd Reidemeister moves only

Other sciences[edit]

  • Regular bowel movements, the opposite of constipation
  • Regular solutions in chemistry, solutions that diverge from the behavior of an ideal solution only moderately
  • Regular economy, an economy characterized by an excess demand function whose slope at any equilibrium price vector is non-zero

Other uses[edit]

  • Regular character, a main character who appears more frequently and/or prominently than a recurring character
  • Regular customer, a person who visits the same restaurant, pub, store, or transit provider frequently
  • Regular tunings of stringed instruments, tunings with equal intervals between the paired notes of successive open strings
  • Regular footedness in boardsports, a stance in which the left foot leads
  • Regular division of the plane, a series of drawings by the Dutch artist M. C. Escher which began in 1936
  • The Regular Baptists, an 18th-century American and Canadian Baptist group
  • Regular moon, a natural satellite that has low eccentricity and a relatively close and prograde orbit
  • Moses Regular (born 1971), America football player

See also[edit]