Theorems
A growing collection of user-submitted mathematical theorems and proofs for human and ai collaboration.
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-2026dAnalysisAlgebraThe absolute value in an ordered field is nonnegative, symmetric and multiplicative, bounds its argument, satisfies the triangle and reverse triangle inequalities and the weak and strict two-sided bounds, and on the reals agrees with the complex modulus.- 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…
Existence and Uniqueness of Iterates of a Binary Operation
lemmalem:iterated-binary-operation-2026aAlgebraSet TheoryLet be a set and let be a binary operation on , that is, a map , whose value at is written . Let be the set of natural numbers with successor map as in that definition, let , let be the…The Complex Coordinate Space is a Complex Hilbert Space
theoremthm:cn-hilbert-space-2026aAnalysisLinear AlgebraLet be a natural number, let be the complex coordinate space with the standard inner product , which is a complex inner product space by The Standard Inner Product Makes the Complex Coordinate Space an Inner Product Space, let…- Let , and be sequences of real numbers, and let be a real number. Limits are as in that definition, and denotes the absolute value of a real number , that is, if and otherwise…
- Limits of real sequences respect sums, products, scalar multiples, differences, and quotients with nonzero limit.
Uniqueness of Limits and Boundedness of Convergent Real Sequences
lemmalem:limit-uniqueness-boundedness-real-2026aAnalysisLet be a sequence of real numbers. Then the following hold. 1. (Uniqueness of limits) If converges to and also converges to , then . 2. (Convergent sequences are bounded) If converges to some real number, then …Convergence in the Complex Numbers by Real and Imaginary Parts, and Completeness in the Modulus Metric
theoremthm:complex-numbers-complete-2026bAnalysisTopologyA sequence of complex numbers converges in the modulus metric exactly when its real and imaginary parts converge, and its limit is then assembled from their limits; the complex numbers with the modulus metric form a complete metric space.- Let together with be a complex inner product space, let be the induced norm, and let be the function assigning to each pair of elements of the real number , which is a metric on by clai…
Symmetry of Orthogonality and the Pythagorean Identity
lemmalem:pythagorean-identity-2026aAnalysisLinear AlgebraLet together with be a complex inner product space, let be the induced norm, let be the zero vector, and let . Then the following hold. 1. (Symmetry) and are orthogonal if and only if and are o…- Let together with be a complex inner product space and let . The vectors and are orthogonal if .
The Computational Basis and the State Vectors of a Qubit
lemmalem:qubit-basis-and-states-2026aAnalysisLinear AlgebraLet the qubit state space be as in that definition, with computational basis vectors and , standard inner product and induced norm . Let be an element of , and let denote the…- Let be the complex coordinate space with , which is a complex vector space by The Complex Coordinate Space is a Complex Vector Space, equipped with the standard inner product, which is an inner product on it by…
- Let together with be a complex inner product space and let be the norm induced by the inner product. A vector is a unit vector if .
The Standard Inner Product Makes the Complex Coordinate Space an Inner Product Space
lemmalem:standard-inner-product-cn-2026aAnalysisLinear AlgebraLet be a natural number, let be the complex coordinate space, which is a complex vector space by The Complex Coordinate Space is a Complex Vector Space, and let be the standard inner product on it. Then the following hold.…Standard Inner Product on the Complex Coordinate Space
definitiondef:standard-inner-product-cn-2026aAnalysisLinear AlgebraLet be a natural number, let be the complex coordinate space, and for a complex number let denote its complex conjugate. The standard inner product on assigns to each pair the complex number…The Complex Coordinate Space is a Complex Vector Space
lemmalem:cn-vector-space-2026aAlgebraLinear AlgebraLet be a natural number and let be the complex coordinate space, with the componentwise operations of that definition. Then with these operations is a complex vector space. Its zero vector is the -tuple al…- Let be a natural number and let be the field of complex numbers. The complex coordinate space is the set of all ordered -tuples of complex numbers, together with the operations defined componentwise by…
- Let be a field. 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 initial segment determined by , that is, the set of natural numbers …