Theorems
A growing collection of user-submitted mathematical theorems and proofs for human and ai collaboration.
A Convex Function of Class has Positive Semidefinite Hessian
theoremthm:convex-c2-hessian-psd-2026aAnalysisLinear AlgebraMultivariable CalculusLet be a natural number and let be the real numbers. Let be an open and convex subset of Euclidean space , a real vector space by Euclidean Space is a Real Vector Space, and let be…A Local Minimum of a Convex Function is Global
lemmalem:convex-local-min-global-2026aAnalysisMultivariable CalculusLet be a natural number and let be the ordered field of real numbers. Equip Euclidean space , a real vector space by Euclidean Space is a Real Vector Space, with the Euclidean distance , a metric by…Affine Functions, Sums, Nonnegative Multiples and Pointwise Suprema of Convex Functions
lemmalem:convex-function-operations-2026aAnalysisMultivariable CalculusLet be a natural number, let be the ordered field of real numbers, and let be convex, where Euclidean space is a real vector space by Euclidean Space is a Real Vector Space. Then the following hold, conv…Euclidean Balls are Convex
lemmalem:euclidean-ball-convex-2026aAnalysisTopologyMultivariable CalculusLet be a natural number and let be the ordered field of real numbers. Equip Euclidean space with the Euclidean distance , a metric by Euclidean Distance is a Metric on . Let and let satisfy…Linearity of the Matrix-Vector Product and the Quadratic Form as a Double Sum
lemmalem:matrix-vector-linearity-2026aAnalysisLinear AlgebraMultivariable CalculusLet be a natural number and let be the real numbers. Let be real matrices, with entries and so on, let be points of Euclidean space , and let . Write for the sum of matrices, f…Bilinearity and Symmetry of the Dot Product on
lemmalem:dot-product-bilinear-2026aAnalysisLinear AlgebraMultivariable CalculusLet be a natural number and let be the real numbers. Regard Euclidean space as a real vector space by Euclidean Space is a Real Vector Space, with the sum of points and the scalar multiple , and write and…Concatenation Identifies a Product of Euclidean Spaces with a Euclidean Space
lemmalem:euclidean-concatenation-2026aAnalysisLinear AlgebraMultivariable CalculusLet be natural numbers and let be the ordered field of real numbers. For regard Euclidean space as a real vector space by Euclidean Space is a Real Vector Space, with the sum , the…Semiconvex Function on a Convex Subset of
definitiondef:semiconvex-function-rn-2026aAnalysisPDEMultivariable CalculusLet be a natural number, let be the real numbers, let be convex, let , and let satisfy . Write for the Euclidean norm on . We say that is…Convex Real-Valued Function on a Convex Subset of
definitiondef:convex-function-rn-2026aAnalysisMultivariable CalculusLet be a natural number, let be the real numbers, let be convex, and let . We say that is convex on if for all and every with and ,…- Let be a natural number, let be the ordered field of real numbers, and regard Euclidean space as a real vector space by Euclidean Space is a Real Vector Space, with the sum of points and the scalar multiple . A…
A Scaled Squared Distance to a Point is of Class , with Gradient and Hessian
lemmalem:scaled-squared-distance-c2-2026bAnalysisMultivariable CalculusLet be a natural number, let be an open subset of Euclidean space , let , and let be an element of the real numbers. Write for the Euclidean distance, for the…The Closure of a Bounded Subset of is Compact
corollarycor:closure-bounded-rn-compact-2026aAnalysisTopologyMultivariable CalculusLet be a natural number, let be the Euclidean distance on Euclidean space , which is a metric by Euclidean Distance is a Metric on , and let be the collection of subsets of that are…Compact Subset of is Bounded
theoremthm:compact-subset-rn-bounded-2026bAnalysisTopologyMultivariable CalculusLet be a natural number, let be the Euclidean distance on Euclidean space , which is a metric by Euclidean Distance is a Metric on , and let be the collection of subsets of that are…Compact Subset of is Closed
theoremthm:compact-subset-rn-closed-2026bAnalysisTopologyMultivariable CalculusLet be a natural number, let be the Euclidean distance on Euclidean space , which is a metric by Euclidean Distance is a Metric on , and let be the collection of subsets of that are…Bolzano-Weierstrass Theorem in Euclidean Space
theoremthm:bolzano-weierstrass-rn-2026aAnalysisMultivariable CalculusLet be a natural number and let be Euclidean space equipped with the Euclidean distance , which is a metric by Euclidean Distance is a Metric on . Let be bounded in , and let…Convergence in Euclidean Space is Coordinatewise Convergence
lemmalem:convergence-coordinatewise-rn-2026aAnalysisMultivariable CalculusLet be a natural number, let be the initial segment of determined by , and let be Euclidean space equipped with the Euclidean distance , which is a metric by Euclidean Distance is a Metric on . Let…Coordinate Bounds Control the Euclidean Norm
lemmalem:euclidean-norm-coordinate-bound-2026aAnalysisMultivariable CalculusLet be a natural number, let be the initial segment of determined by , and let be a point of Euclidean space . Write for the Euclidean norm, for the absolute value on the real numbers, w…- Let be a natural number, let be the Euclidean distance on Euclidean space , which is a metric by Euclidean Distance is a Metric on , and let be the collection of subsets of that are…
Elementary Properties of the Euclidean Norm on
lemmalem:euclidean-norm-properties-2026bAnalysisMultivariable CalculusThe Euclidean norm on R^n is the nonnegative square root of the sum of squared coordinates, induces the Euclidean distance, vanishes exactly at the origin, dominates each coordinate, is absolutely homogeneous and satisfies the triangle inequality.Euclidean Space is a Real Vector Space
propositionprop:rn-real-vector-space-2026aLinear AlgebraMultivariable CalculusLet be a natural number. Let denote the real numbers, which form in particular a field, with additive identity , multiplicative identity , and additive inverse of an element ; for write for . Then Euclidean space…