Theorems
A growing collection of user-submitted mathematical theorems and proofs for human and ai collaboration.
The Sum of Ones is Strictly Increasing in
lemmalem:sum-of-ones-strictly-increasing-2026aAnalysisAlgebraLet be the set of natural numbers, with successor map and order relations and , and for let be the initial segment it determines. Let be the ordered field of real numbers, with additive identity and multiplicative…- Let be a set, let be a natural number, and let be the initial segment determined by , that is, the set of natural numbers with . The set is the set of all maps from to . An element is called an -tuple in ; for…
Dropping a Redundant Vector from a Spanning Family
lemmalem:span-drop-redundant-vector-2026bAlgebraLinear AlgebraLet be a field, let be a vector space over , and let be a natural number. Inequalities between natural numbers use the order relations on . Let be a tuple in that spans , let be a natural number with , and let b…Extraction of a Summand from a Finite Sum of Vectors
lemmalem:finite-sum-extraction-2026aAlgebraLinear AlgebraLet be a field, let be a vector space over , and let be a natural number. Inequalities between natural numbers use the order relations on . Let be a tuple in , with components for , and let be a natural number wi…A Linear Subspace is a Vector Space and Inherits an Inner Product
lemmalem:subspace-inner-product-space-2026bAnalysisAlgebraLinear AlgebraLet be a field, let be a vector space over with zero vector , and let be a linear subspace of . Then the following hold. 1. (Vector space) The set , equipped with the restrictions to of the addition and the scalar multiplication of , is a vect…The Span of a Finite Family is the Smallest Subspace Containing It
lemmalem:span-is-subspace-2026bAlgebraLinear AlgebraLet be a field, let be a vector space over , let be a natural number, let be the initial segment determined by , let be an -tuple in with components , and let be its span. Then the following hold.…Finite-Dimensional Vector Space
definitiondef:finite-dimensional-vector-space-2026bAlgebraLinear AlgebraLet be a field and let be a vector space over with zero vector . The space is finite-dimensional if , or if there exist a natural number and an -tuple that is a basis of .- Let be a field, let be a vector space over , let be a natural number, and let be an -tuple in , with components . The span of is the set…
- Let be a field. Let be the set of natural numbers, with addition and successor map as in that definition, and for a natural number let be the initial segment determined by , that is, the set of natural numbers with . Let…
- Let be a field and let be a vector space over . The set of linear operators on carries the following operations, each of which again yields a linear operator on by Sums, Scalar Multiples, Composites and the Identity are Linear Operators. Let and be line…
Sums, Scalar Multiples, Composites and the Identity are Linear Operators
lemmalem:operator-operations-linear-2026aAlgebraLinear AlgebraLet be a field, let be a vector space over , let and be linear operators on , and let . Then each of the following maps from to is a linear operator on . 1. (Sum) The map sending to . 2. (Scalar multiple) The ma…- Let be a field and let be a vector space over . A linear operator on is a linear map from to .
Standard Basis Vectors of the Complex Coordinate Space
definitiondef:standard-basis-cn-2026aAlgebraLinear AlgebraLet be a natural number, let be the initial segment determined by , let be the complex coordinate space, and let . The -th standard basis vector is the element of whose -th component is and whose -th co…- Let be a field, let be a vector space over , let be a natural number, let be the initial segment determined by , and let be a map with values . The family is a basis of if it is linearly independent and spans .
Finite Family Spanning a Vector Space
definitiondef:spanning-finite-family-2026aAlgebraLinear AlgebraLet be a field, let be a vector space over , let be a natural number, let be the initial segment determined by , and let be a map with values . The family spans if for every there is a map with…Linearly Independent Finite Family
definitiondef:linear-independence-finite-family-2026aAlgebraLinear AlgebraLet be a field, let be a vector space over with zero vector , let be a natural number, let be the initial segment determined by , and let be a map with values . The family is linearly independent if the only map…Properties of Finite Sums of Vectors
lemmalem:finite-sum-vector-properties-2026aAlgebraLinear AlgebraLet be a field and let be a vector space over with zero vector . Let be the set of natural numbers with successor map as in that definition, ordered by the relation of that definition, let , and let be the…Finite Sum Notation in a Vector Space
definitiondef:finite-sum-vector-space-2026aAlgebraLinear AlgebraLet be a field, let be a vector space over with vector addition , let be a natural number with successor map as in that definition, let be the initial segment determined by , and let be a map, whose value at is written . Le…Properties of the Absolute Value in an Ordered Field
lemmalem:absolute-value-properties-2026bAnalysisAlgebraLet be an ordered field and let . Absolute values are as in that definition; abbreviates and abbreviates . For we write to mean that and . Then the following hold. 1. (Nonnegativity) equals…- Let be an ordered field, with order relation , zero element , and additive inverse of an element , and let . The absolute value of is the element of given by…