Theorems
A growing collection of user-submitted mathematical theorems and proofs for human and ai collaboration.
- Let be a natural number and let be a point of Euclidean space , so that each coordinate is a real number. The real numbers form an ordered field, with additive identity and order ; write for . By claim 2 of…
- Let be a natural number, and let denote the additive identity of the field of real numbers. The origin of Euclidean space is the point all of whose coordinates equal .
Scalar Multiple of a Point of
definitiondef:scalar-multiple-rn-2026aLinear AlgebraMultivariable CalculusLet be a natural number, let be a real number, and let be a point of Euclidean space . The scalar multiple is the point of defined by where in each coordin…- Let be a natural number, and let and be points of Euclidean space , so that each and each is a real number. The sum is the point of defined by where in e…
First- and Second-Order Conditions at a Local Extremum of a Function of Class
lemmalem:c2-local-extremum-conditions-2026bAnalysisLinear AlgebraMultivariable CalculusLet be a natural number, let be an open subset of Euclidean space , let be the real numbers, let be of class on , and let . Regard as a metric space through the…Differences and Constants for Functions of Class on a Euclidean Open Set
lemmalem:c2-difference-constant-2026bAnalysisMultivariable CalculusLet be a natural number, let be an open subset of Euclidean space , and let be the real numbers. Let be of class on , and let be the function whose value at…Euclidean Continuity Agrees with Metric Continuity for Real-Valued Functions
lemmalem:euclidean-metric-continuity-agree-2026aAnalysisTopologyMultivariable CalculusLet be a natural number, let be a subset of Euclidean space , let be the set of real numbers with the operations and the order of its ordered field structure, where for we write to mean that…Gradient of a Real-Valued Function on a Euclidean Open Set
definitiondef:gradient-euclidean-open-set-2026bAnalysisMultivariable CalculusLet be a natural number, let be an open subset of Euclidean space , let be the set of real numbers, let , and let . Assume that for every the partial derivative of with respe…- Let be a natural number, let be the real numbers, let be an open subset of Euclidean space , and let , regarded where a map into a Euclidean space is required as the map into whose single coordinate function…
A Real-Valued Function is Differentiable at Every Point
theoremthm:c1-implies-differentiable-2026bAnalysisMultivariable CalculusLet be a natural number, let be an open subset of Euclidean space , let be a real-valued function, regarded also as a map into with single coordinate function , and let . Suppose that is…Second-Order Taylor Expansion with Peano Remainder
theoremthm:second-order-taylor-peano-2026bAnalysisMultivariable CalculusLet be a natural number, let be an open subset of Euclidean space , let be the real numbers with the operations, order and absolute value of their ordered field structure, and let be of class on (via cl…Equality of Mixed Second Partial Derivatives and Symmetry of the Hessian
theoremthm:hessian-symmetric-2026bAnalysisLinear AlgebraMultivariable CalculusLet be a natural number, let be an open subset of Euclidean space , let be the real numbers, let be of class on , and let . Then the following hold.…Slice Function and the Partial Derivative
lemmalem:slice-function-partial-derivative-2026bAnalysisMultivariable CalculusLet be a natural number, let be an open subset of Euclidean space , let with the set of real numbers, let , and let . Let be the absolute value on…Hessian Matrix of a Function
definitiondef:hessian-matrix-2026bAnalysisLinear AlgebraMultivariable CalculusLet be a natural number, let be an open subset of Euclidean space , let be the real numbers, let be of class on , and let . The Hessian matrix of at , denoted , is the rea…Real-Valued Map on an Open Subset of Euclidean Space
definitiondef:c2-map-euclidean-open-set-2026aAnalysisMultivariable CalculusLet be a natural number, let be an open subset of Euclidean space , and let , where is the set of real numbers. We say that is of class on if the following two conditions hold. 1. is…Pythagorean Theorem in Euclidean Space
theoremthm:pythagorean-theorem-rn-2026aGeometryMultivariable CalculusLet , and let , , be points of Euclidean space . Assume that the differences and are orthogonal, that is, Then, with denoting the Euclidean distance on ,…Difference, Dot Product, and Orthogonality in
definitiondef:dot-product-orthogonality-rn-2026aGeometryMultivariable CalculusLet , and let and be points of Euclidean space . 1. The difference is the point of defined by where in each coordinate the difference is that of real…Integral of a Smooth n-Form over a Compact Oriented Smooth Manifold with Boundary
definitiondef:integral-form-oriented-manifold-boundary-2026aAnalysisGeometryMultivariable CalculusLet and let be an oriented smooth manifold with boundary of dimension that is compact in the sense of Smooth Atlas and Smooth Manifold with Boundary, with chosen oriented smooth atlas , and write…Independence of the Manifold Integral from Chart and Partition Choices
theoremthm:integral-manifold-independence-choices-2026aAnalysisGeometryMultivariable CalculusLet and let be an oriented smooth manifold with boundary of dimension that is compact in the sense of Smooth Atlas and Smooth Manifold with Boundary, with chosen oriented smooth atlas , and write…Restriction of a Smooth Differential Form to the Boundary
definitiondef:restriction-form-boundary-manifold-2026bTopologyGeometryMultivariable CalculusLet with , let be a smooth manifold with boundary of dimension with nonempty boundary , and equip with the smooth manifold structure of dimension from…