Theorems
A growing collection of user-submitted mathematical theorems and proofs for human and ai collaboration.
A Convex Function is Continuous near an Interior Point
corollarycor:convex-function-continuous-near-interior-point-2026aAnalysisMultivariable CalculusLet , , , , the Euclidean norm , the Euclidean metric and the closed balls of Closed Ball in a Metric Space be as in A Convex Function is Lipschitz on a Ball around an Interior Point. Regard…A Convex Function is Lipschitz on a Ball around an Interior Point
theoremthm:convex-function-lipschitz-near-interior-point-2026aAnalysisMultivariable CalculusLet be a natural number with , let be the initial segment determined by , and let be the set of real numbers with the operations and the order of its ordered field structure, with the absolute value written . On Euclidean space…Increment Bound for a Convex Function through an Extended Point
lemmalem:convex-function-increment-bound-2026aAnalysisMultivariable CalculusLet be a natural number with , let be the set of real numbers with the operations and the order of its ordered field structure, let be a convex subset of Euclidean space , a real vector space by…A Convex Function Bounded Above on a Set Symmetric about a Point is Bounded Below on It
lemmalem:convex-function-bounded-below-reflection-2026aAnalysisMultivariable CalculusLet be a natural number with , let be the set of real numbers with the operations and the order of its ordered field structure, let be a convex subset of Euclidean space , a real vector space by…A Convex Function is Bounded Above near a Point by its Values at Coordinate Neighbours
lemmalem:convex-function-bounded-above-crosspolytope-2026aAnalysisMultivariable CalculusLet be a natural number with , let be the initial segment determined by , and let be the set of real numbers with the operations and the order of its ordered field structure, with the absolute value written . Let be a convex su…Determinant Bound for a Matrix Squeezed between a Negative Multiple of the Identity and Zero
corollarycor:determinant-bound-semidefinite-interval-2026aAnalysisLinear AlgebraLet be a natural number, let be the initial segment determined by , and let be the set of real numbers with the operations and the order of its ordered field structure, with the absolute value written . Let with…Hadamard's Inequality for a Positive Semidefinite Matrix
theoremthm:hadamard-determinant-inequality-psd-2026aAnalysisLinear AlgebraLet be a natural number, let be the initial segment determined by , let be the set of real numbers with the operations and the order of its ordered field structure, and let be a symmetric positive semidefinite real matrix, with entr…Properties of Natural Number Powers in a Field
lemmalem:natural-power-properties-2026bAnalysisAlgebraNatural powers in a field satisfy the recursion and the unit and product rules, vanish only at 0, and add exponents; for real bases they are monotone in a nonnegative base and, for bases at least 1, in the exponent.Cauchy-Schwarz Inequality for a Positive Semidefinite Quadratic Form on
lemmalem:psd-cauchy-schwarz-rn-2026aAnalysisLinear AlgebraLet be a natural number with , let be the real numbers with the order of its ordered field structure, and let be a symmetric positive semidefinite real matrix. On Euclidean space , a real vector space by…- Let be a field, with additive identity and multiplicative identity . Let be the set of natural numbers with successor map as in that definition, ordered by the relations of Order on the Natural Numbers, let , and let be the…
Jensen's Inequality for Finite Convex Combinations
theoremthm:jensen-inequality-finite-2026aAnalysisMultivariable CalculusLet and be natural numbers with and , let be the real numbers with the order of its ordered field structure, and let be the initial segment determined by . Let be a convex subset of Euclidean space , regarded…Properties of the Norm of a Symmetric Real Matrix
lemmalem:symmetric-matrix-norm-properties-2026aAnalysisLinear AlgebraMultivariable CalculusLet be a natural number with and let be the real numbers with the order of its ordered field structure and the absolute value . Let and be symmetric real matrices and let . Write for the…Small Cases, Reduction, and Membership for Convex Combinations
lemmalem:convex-combination-properties-2026aAnalysisLinear AlgebraMultivariable CalculusLet and be natural numbers with and , let be the real numbers with the order of its ordered field structure, and for a natural number let be the initial segment determined by . Regard Euclidean space as a rea…A Closed Euclidean Ball is Convex and Compact
lemmalem:closed-euclidean-ball-convex-compact-2026aAnalysisTopologyMultivariable CalculusLet be a natural number with , let be the real numbers with the order of its ordered field structure, let be a point of Euclidean space , regarded as a real vector space by Euclidean Space is a Real Vector Space, and…- Let be a natural number with and let be a symmetric real matrix. On Euclidean space write for the dot product, for the Euclidean norm of a point , and for the matrix-vector product; let…
Testing a Block Semidefinite Inequality on the Diagonal
lemmalem:block-order-implies-matrix-order-2026aAnalysisLinear AlgebraMultivariable CalculusLet be a natural number with , let be the real numbers, let , and let and be symmetric real matrices. Write for the identity matrix of size , write for the real matrix all of whose entrie…Elementary Properties of the Closed Ball in a Metric Space
lemmalem:closed-ball-properties-metric-2026aAnalysisTopologyLet be a metric space, let , let be a real number with , the order being that of the ordered field of real numbers, and let be the closed ball. Let be the collection of subsets of that are open in , a t…The Quadratic Form of a Real Square Matrix is Bounded on the Closed Unit Ball
lemmalem:matrix-quadratic-form-bounded-2026aAnalysisLinear AlgebraMultivariable CalculusLet be a natural number with , let be the initial segment determined by , and let be the real numbers with the order of its ordered field structure and the absolute value . Let be a real matrix, with entries…The Positive Semidefinite Ordering is a Partial Order Compatible with the Linear Structure
lemmalem:psd-ordering-partial-order-2026aAnalysisLinear AlgebraLet be a natural number with , let be the initial segment determined by , and let be the real numbers with the order of its ordered field structure. Let , and be symmetric real matrices and let . Wri…Action and Quadratic Form of a Block Matrix
lemmalem:block-matrix-quadratic-form-2026aAnalysisLinear AlgebraMultivariable CalculusLet and be natural numbers with and , let be the real numbers, and for a natural number let be the initial segment determined by . Let , , and be real matrices of sizes , , and…