Mathematics and statistics

Nicolas Bourbaki

Nicolas Bourbaki is the collective pseudonym of a semi-secret, self-renewing society of mathematicians, founded by young French mathematicians in 1935, whose monumental treatise Éléments de mathématique reshaped mathematics.

Nicolas Fatio de Duillier

Nicolas Fatio de Duillier, also known as Nicolas Fatio, was a Swiss mathematician and natural philosopher, a friend of Isaac Newton who proposed a corpuscular theory of gravity in 1690.

Nicolo Tartaglia

Nicolo Tartaglia, born Niccolo Fontana, was an Italian mathematician and engineer who solved a class of cubic equations and wrote the first printed treatise on ballistics.

Niels Henrik Abel

Niels Henrik Abel (1802–1829) was a Norwegian mathematician who proved the general fifth-degree equation cannot be solved by radicals, founded elliptic function theory, and died of tuberculosis at 26.

Nikolai Lobachevsky (Николай Иванович Лобачевский)

Nikolai Lobachevsky, also known as Nikolai Ivanovich Lobachevsky, was a Russian mathematician (1792–1856) who first published non-Euclidean, now hyperbolic, geometry while rector of Kazan University.

Nilpotent element

A nilpotent element of a ring is an element x whose some power x raised to n equals 0, making every nilpotent a zero divisor though not conversely, as with 2 in the integers mod 6.

Nilpotent group

A nilpotent group is a group whose lower central series, built by repeatedly taking commutators, reaches the trivial subgroup after finitely many steps; class 1 groups are exactly abelian.

Nilpotent Lie algebra

A nilpotent Lie algebra is a Lie algebra in which all iterated brackets of sufficient length equal zero, so it is nearly abelian and underlies nilpotent Lie groups.

Nilpotent matrix

A nilpotent matrix, or nilpotent transformation, is a square matrix for which some finite power is the zero matrix, and 0 is its only eigenvalue.

Nilradical

The nilradical of a commutative ring is the ideal of all nilpotent elements, also equal to the intersection of all prime ideals of the ring.

Nilsystem

A nilsystem is a dynamical system on a compact nilmanifold G/Γ of a nilpotent Lie group, with translation dynamics; nilsystems are the characteristic factors in multiple ergodic averages.

Nimber

A nimber, also called a Grundy value or nim-value, is the value assigned to a position in an impartial combinatorial game; a nonzero nimber means a winning position.

NIP theory

NIP theory, also called a dependent theory, is a first-order theory in which no formula has the independence property. Introduced by Saharon Shelah, it is a central tameness dividing line in model theory.

No-U-Turn Sampler

The No-U-Turn Sampler (NUTS) is a Markov chain Monte Carlo algorithm extending Hamiltonian Monte Carlo, which sets trajectory length automatically so no hand-tuning is needed.

Noether normalization lemma

The Noether normalization lemma, a result in commutative algebra proved by Emmy Noether in 1926, states that every finitely generated algebra over a field is a finite extension of a polynomial subring.

Noetherian ring

A Noetherian ring is a ring in which every ideal can be generated by finitely many elements, named after Emmy Noether, who studied them in 1921.

Nominalism

Nominalism, also called via moderna, is the metaphysical view that only particular, concrete things exist, denying universals and abstract entities; William of Ockham was its key medieval exponent.

Oct 21, 2026

Nomograms

Nomograms: graphical charts of statistical prediction models with scales for each variable, used in medicine to compute individualized probabilities of clinical endpoints, notably in cancer prognosis (Partin tables).

Non-associative algebra

A non-associative algebra is an algebra over a field whose multiplication need not satisfy x(yz) = (xy)z; Lie, Jordan, and alternative algebras are the best-known examples.

Non-dimensionalization

Non-dimensionalization rescales the variables of a governing equation by characteristic units so that the equation, its solutions, and its parameters become dimensionless, simplifying comparison and simulation.

Non-Euclidean geometry

Non-Euclidean geometry, also known as non-Euclidean space, is geometry built on alternatives to Euclid's parallel postulate, arising in the early nineteenth century from the work of Gauss, Bolyai, and Lobachevski.

Non-linear least squares

Non-linear least squares is a parameter estimation method that fits models nonlinear in their parameters by minimizing squared residuals, typically with the Gauss-Newton or Levenberg-Marquardt algorithm.

Non-metric multidimensional scaling

Non-metric multidimensional scaling (NMDS) is a statistical technique that represents objects as points in low-dimensional space, preserving only the rank order of observed dissimilarities, not their numerical values.

Non-negative least squares

Non-negative least squares (NNLS) is a constrained regression method fitting a linear least squares model with every coefficient zero or positive, used in deconvolution and unmixing.

Non-negative matrix factorization

Non-negative matrix factorization (NMF) is a family of algorithms approximating a nonnegative matrix as a product of two lower-rank nonnegative matrices, giving additive, parts-based representations of data.

Non-normal modal logic

A non-normal modal logic is a modal logic weaker than the smallest normal logic K, lacking necessitation or the K axiom, and interpreted over neighborhood (Scott–Montague) models.

Non-oscillatory scheme

A non-oscillatory scheme is a numerical method for hyperbolic partial differential equations that suppresses spurious oscillations near shocks and discontinuities while keeping high-order accuracy in smooth regions.

Non-probability sampling

Non-probability sampling is a survey sampling approach in which units are chosen non-randomly, by convenience, judgment, or quotas, making selection probabilities unknown and inference dependent on untestable models.

Non-standard model

A non-standard model is a mathematical structure satisfying the same first-order axioms as a standard structure like the natural numbers, yet containing extra elements such as infinite integers.