Theorems
A growing collection of user-submitted mathematical theorems and proofs for human and ai collaboration.
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 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 …
- Let be a field, 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 . Let be the map given by…
- Let be a field and let and be vector spaces over . A map is linear if 1. for all ; 2. for all and , where on the left-hand sides the operations are those of and on th…
- Let be a field, let be a vector space over , and let be its zero vector. A subset of is a linear subspace of if 1. ; 2. for all ; 3. for all and .
Elementary Identities in a Vector Space
lemmalem:vector-space-basic-identities-2026aAlgebraLinear AlgebraLet be a field and let be a vector space over , with the conditions 1-8 of that definition. Then the following hold. 1. (Uniqueness of the zero vector) There is exactly one element with for every . 2. (Uniqueness of additive inverses)…- Let be a field, with additive identity and multiplicative identity . A vector space over is a set together with two operations: an addition, assigning to each pair of elements of an element of , and a scalar multiplication, assigning to each…
Canonical Form and Arithmetic of Complex Numbers
lemmalem:complex-canonical-form-2026aAnalysisAlgebraLet be the field of complex numbers with imaginary unit , and let be the set of real numbers. Then the following hold. 1. (Identities and inverses of real numbers) The additive identity of is the real number and the multiplicative id…Existence and Uniqueness of the Complex Numbers
theoremthm:complex-numbers-existence-uniqueness-2026aAnalysisAlgebraLet be the set of real numbers, with its addition, its multiplication and its order. Call a pair , consisting of a field and an element , a complex pair if the following three conditions hold, where and denote the addition and multipli…Properties of Complex Conjugation and Modulus
lemmalem:complex-conjugate-modulus-properties-2026aAnalysisAlgebraLet be the field of complex numbers with imaginary unit , let be the set of real numbers, and let . Sums, products and inverses are those of the field , and abbreviates ; for a real number , abbrevia…- Let be the field of complex numbers, let , and let and be its real and imaginary parts. The modulus of , written , is the unique real number with and ; such an …
- Let be the field of complex numbers with imaginary unit , let , and let and be its real and imaginary parts. The complex conjugate of is the complex number…
Real and Imaginary Parts of a Complex Number
definitiondef:complex-real-imaginary-part-2026aAnalysisAlgebraLet be the field of complex numbers with imaginary unit , and let . By claim 3 of Canonical Form and Arithmetic of Complex Numbers there is exactly one pair of real numbers with . The real part of is the real number…- Let be the set of real numbers, with its addition and multiplication. The complex numbers are a field , whose addition and multiplication are written and (the product being also written ), together with a distinguished element…
- Let be a group whose underlying set is finite, and let be a subgroup of . Then the following hold. 1. The sets and , where is the set of left cosets of in , are finite and nonempty, and where is the order of …
Left Cosets Partition a Group and All Have the Same Cardinality
theoremthm:coset-partition-2026aAlgebraLet be a group, written multiplicatively, with identity element and inverses as in Uniqueness of the Identity Element and of Inverses in a Group, and let be a subgroup of . For let be the left coset determined by . Then for all…Left Coset, Order of a Group, and Index of a Subgroup
definitiondef:left-coset-order-index-2026aAlgebraLet be a group, written multiplicatively as , and let be a subgroup of . For , the left coset of determined by is the subset of given by The collection of all left cosets of in is denoted…A Group Homomorphism is Injective Exactly When its Kernel is Trivial
theoremthm:trivial-kernel-injective-2026aAlgebraLet and be groups with identity elements and as in Uniqueness of the Identity Element and of Inverses in a Group, and let be a group homomorphism. Then is injective if and only if its kernel satisfies…