• The direct sum is an operation between structures in abstract algebra, a branch of mathematics. It is defined differently but analogously for different...
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  • In abstract algebra, the direct sum is a construction which combines several modules into a new, larger module. The direct sum of modules is the smallest...
    22 KB (3,556 words) - 22:52, 3 December 2024
  • Thumbnail for Direct sum of groups
    In mathematics, a group G is called the direct sum of two normal subgroups with trivial intersection if it is generated by the subgroups. In abstract algebra...
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  • Πi∈I Ri coincides with the direct sum of the additive groups of the Ri. In this case, some authors call R the "direct sum of the rings Ri" and write ⊕i∈I...
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  • The direct sum of two matrices is the diagonal matrix where the top-left and bottom-right corners of the matrix fill the two given matrices, and where...
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  • Thumbnail for Semidirect product
    group theory, the concept of a semidirect product is a generalization of a direct product. It is usually denoted with the symbol ⋉. There are two closely...
    31 KB (4,596 words) - 07:48, 6 May 2025
  • grading or gradation, which is a decomposition of the vector space into a direct sum of vector subspaces, generally indexed by the integers. For "pure" vector...
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  • Thumbnail for Block matrix
    dimensions). Note that any element in the direct sum of two vector spaces of matrices could be represented as a direct sum of two matrices. A block diagonal matrix...
    31 KB (5,119 words) - 16:01, 28 May 2025
  • mathematics, the disjoint union (also called the direct sum, free union, free sum, topological sum, or coproduct) of a family of topological spaces is...
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  • Thumbnail for Matrix addition
    Matrix multiplication Vector addition Direct sum of matrices Kronecker sum Elementary Linear Algebra by Rorres Anton 10e p53 Lipschutz...
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  • a direct sum of unitaries acting on 1-dimensional complex spaces (eigenspaces), but an antiunitary operator may only be decomposed into a direct sum of...
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    canonically isomorphic to the direct sum of Vi. In this case, H is called the internal direct sum of the Vi. A direct sum (internal or external) is also...
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  • a combination of algebraic objects Direct sum of groups Direct sum of modules Direct sum of permutations Direct sum of topological groups Einstein summation...
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  • Thumbnail for Abelian group
    each subgroup gives rise to a quotient group. Subgroups, quotients, and direct sums of abelian groups are again abelian. The finite simple abelian groups...
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  • In combinatorics, the skew sum and direct sum of permutations are two operations to combine shorter permutations into longer ones. Given a permutation...
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  • Thumbnail for Vector bundle
    Whitney sum (named for Hassler Whitney) or direct sum bundle of E and F is a vector bundle E ⊕ F over X whose fiber over x is the direct sum Ex ⊕ Fx of...
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  • the direct sum of representations please refer to the section on direct sums of representations. A representation is called isotypic if it is a direct sum...
    105 KB (21,294 words) - 10:21, 1 April 2025
  • Thumbnail for Direct product of groups
    notions of direct product in mathematics. In the context of abelian groups, the direct product is sometimes referred to as the direct sum, and is denoted...
    26 KB (2,932 words) - 23:03, 19 April 2024
  • categorical sum, is a construction which includes as examples the disjoint union of sets and of topological spaces, the free product of groups, and the direct sum...
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  • the algebraic direct sum by requiring certain maps be continuous; the result retains many nice properties from the operation of direct sum in finite-dimensional...
    21 KB (3,308 words) - 07:43, 15 October 2024
  • mathematics, a topological group G {\displaystyle G} is called the topological direct sum of two subgroups H 1 {\displaystyle H_{1}} and H 2 {\displaystyle H_{2}}...
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  • illustration of the tensor product of algebras, and as an illustration of the direct sum of algebras. The split-biquaternions have been identified in various ways...
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  • Thumbnail for Vector space
    similar to the corresponding statements for groups. The direct product of vector spaces and the direct sum of vector spaces are two ways of combining an indexed...
    87 KB (11,491 words) - 12:05, 7 May 2025
  • it is the direct sum of simple (irreducible) submodules. For a module M, the following are equivalent: M is semisimple; i.e., a direct sum of irreducible...
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  • representation) is a linear representation of a group or an algebra that is a direct sum of simple representations (also called irreducible representations). It...
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  • This ordering is more natural if one thinks of the complex space as a direct sum of real spaces, as discussed below. The data of the real vector space...
    17 KB (2,918 words) - 07:21, 22 February 2025
  • to a direct sum of copies of the ring R. These are the modules that behave very much like vector spaces. Projective Projective modules are direct summands...
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  • sets, particularly on infinite products, as in the product topology or direct sum. This use of the prefix "co" to describe a property possessed by a set's...
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  • on C, Direct sum There is an isomorphism h from B to the direct sum of A and C, such that hq is the natural injection of A into the direct sum, and r...
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  • x {\displaystyle x} and every e ∈ E x , {\displaystyle e\in E_{x},} a direct sum decomposition of T X ( x ) E {\displaystyle T_{X(x)}E} into two linear...
    45 KB (8,674 words) - 23:09, 1 January 2025