Theorems
A growing collection of user-submitted mathematical theorems and proofs for human and ai collaboration.
Properties of the Canonical Map from the Natural Numbers to an Ordered Field
lemmalem:natural-number-image-properties-2026aAnalysisAlgebraLet be an ordered field, with the addition, multiplication, additive identity , multiplicative identity and multiplicative inverses of the underlying field, and with its order ; for write to mean and . Let be…The Canonical Map from the Natural Numbers to a Field
definitiondef:natural-number-image-field-2026aAlgebraSet TheoryLet be a field with multiplicative identity , let be the set of natural numbers, and for let be the initial segment of determined by . For let be the map with for every…- Let be a set equipped with a total order , and let . Then has at most one least upper bound in , and at most one greatest lower bound in . Accordingly, when a least upper bound of exists it is denoted , and when a greatest lower bound…
Lower Bound and Greatest Lower Bound in a Totally Ordered Set
definitiondef:lower-bound-infimum-total-order-2026aAnalysisAlgebraLet be a set equipped with a total order , and let . An element is a lower bound for if for every . If such an exists, then is bounded below. An element is a greatest lower bound, or infimum, of if…Elementary Properties of the Minimum of Two Elements
lemmalem:minimum-two-elements-properties-2026aAlgebraLogicLet be a set equipped with a total order , let , let denote the minimum of and , and let denote their maximum. Then the following hold. 1. (Lower bound) and . 2. (Attainment)…Minimum of Two Elements of a Totally Ordered Set
definitiondef:minimum-two-elements-2026aAlgebraLogicLet be a set equipped with a total order , and let . The minimum of and , written , is the element of defined as follows: if , then is ; otherwise is .Elementary Properties of the Maximum of Two Elements
lemmalem:maximum-two-elements-properties-2026aAlgebraLogicLet be a set equipped with a total order , let , and let denote the maximum of and . Then the following hold. 1. (Upper bound) and . 2. (Attainment) or .…Maximum of Two Elements of a Totally Ordered Set
definitiondef:maximum-two-elements-2026aAlgebraLogicLet be a set equipped with a total order , and let . The maximum of and , written , is the element of defined as follows: if , then is ; otherwise is .Nonnegativity of Squares in an Ordered Field
lemmalem:square-nonnegative-ordered-field-2026aAnalysisAlgebraLet together with be an ordered field, with additive identity . For write for , and write for the absolute value of . Let . Then the following hold. 1. (Agreement with the absolute value) .…Additive Cancellation and Elementary Additive Identities in a Field
lemmalem:field-additive-identities-2026aAlgebraLet be a field, with additive identity and with the additive inverse of an element as in that definition, and write for . Let . Then the following hold. 1. (Uniqueness of additive inverses) If , then and .…Monotonicity of Squaring on the Nonnegative Elements of an Ordered Field
lemmalem:squares-monotone-nonnegative-2026aAnalysisAlgebraLet together with be an ordered field, with additive identity , and for let denote the associated strict order, that is, together with . For write for . Let satisfy…Elementary Order Arithmetic in an Ordered Field
lemmalem:ordered-field-order-arithmetic-2026aAnalysisAlgebraLet together with be an ordered field, with additive identity and multiplicative identity , and with the addition and multiplication of its underlying field; its order is in particular a total order. For write to mean that and…- Let be a field, with additive identity , multiplicative identity , additive inverse of an element , and multiplicative inverse of an element . Write and ; a sum of three terms is written without brackets, which is una…
- Let be a complex vector space, let be a linear operator on , and let be a complex number. The number is an eigenvalue of if there exists a vector that is an eigenvector of with eigenvalue .
- Let be a complex vector space with zero vector , let be a linear operator on , let be a complex number, and let . The vector is an eigenvector of with eigenvalue if and
- Let be an ordered field, with the additive identity , multiplicative identity , additive inverses and multiplicative inverses of a field, and with its order ; write . Let . Then the following hold.…
A Finite Spanning Family Contains a Basis
lemmalem:spanning-family-contains-basis-2026aAlgebraLinear AlgebraLet be a field, let be a vector space over with zero vector , and suppose . Let be a natural number and let be an -tuple in that spans . Then there are a natural number with , in the order on ,…Elementary Properties of Linear Independence
lemmalem:linear-independence-elementary-2026aAlgebraLinear AlgebraLet be a field, let be a vector space over with zero vector , let be a natural number with the order relations and , and let be an -tuple in . For , with the initial segment determined by , write…A Finite Sum of Vectors with Vanishing Tail
lemmalem:finite-sum-vanishing-tail-2026aAlgebraLinear AlgebraLet be a field, let be a vector space over with zero vector , let be a natural number, let be the initial segment it determines, and let be the strict order on . Let be an -tuple in and let be such that…- Let be a field, let be natural numbers, and let and be the initial segments they determine. Let be an -tuple of -tuples in , with components for and , and let and be given…