From Wikipedia, the free encyclopedia

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


Arts, entertainment, and media[edit]


Other uses in arts, entertainment, and media[edit]



There are 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


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


Science and social science[edit]

  • Regular bowel movements, the opposite of constipation
  • Regular economy, an economy characterized by an excess demand function whose slope at any equilibrium price vector is non-zero
  • Regular moon, a natural satellite that has low eccentricity and a relatively close and prograde orbit
  • Regular solutions in chemistry, solutions that diverge from the behavior of an ideal solution only moderately

Other uses[edit]

  • Regular customer, a person who visits the same restaurant, pub, store, or transit provider frequently
  • Regular (footedness) in boardsports, a stance in which the left foot leads

See also[edit]


  1. ^ Axenovich, Maria; Person, Yury; Puzynina, Svetlana (2013). "A regularity lemma and twins in words". Journal of Combinatorial Theory. Series A. 120 (4): 733–743. doi:10.1016/j.jcta.2013.01.001. S2CID 5923754.
  2. ^ Guruswami, Venkatesan; He, Xiaoyu; Li, Ray (2022). "The zero-rate threshold for adversarial bit-deletions is less than 1/2". 2021 IEEE 62nd Annual Symposium on Foundations of Computer Science (FOCS). pp. 727–738. arXiv:2106.05250. doi:10.1109/FOCS52979.2021.00076. ISBN 978-1-6654-2055-6. S2CID 235377196.