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Diff — Dual space

Revision #2560 → #3168 · back to history

modifiedContinuous dual space (intro)33f0b69422c1
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mathlib.moduleMathlib.Topology.Algebra.Module.LinearMapMathlib.Topology.Algebra.Module.ContinuousLinearMap.Basic
modifiedAlgebraic dual space8f0f4355ddc9
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anchors[{"section":"Algebraic dual space","snippet":"is defined as the set of all linear maps"},{"type":"math_alttext","value":"{\\displaystyle {\\begin{aligned}(\\varphi +\\psi )(x)&=\\varphi (x)+\\psi (x)\\\\(a\\varphi )(x)&=a\\left(\\varphi (x)\\right)\\end{aligned}}}"}]
modifiedA linear functional on R^281895c411ce7
FieldFrom #2560To #3168
anchors[{"section":"Algebraic dual space","snippet":"For example, if we express the vector space"},{"type":"math_alttext","value":"{\\displaystyle {\\begin{aligned}(\\varphi +\\psi )(x)&=\\varphi (x)+\\psi (x)\\\\(a\\varphi )(x)&=a\\left(\\varphi (x)\\right)\\end{aligned}}}"}]
modifiedDual basis (finite-dimensional)41735d4ff9d0
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anchors[{"section":"Finite-dimensional case","snippet":"the dual basis is a set"},{"type":"math_alttext","value":"{\\displaystyle \\mathbf {e} ^{i}(c^{1}\\mathbf {e} _{1}+\\cdots +c^{n}\\mathbf {e} _{n})=c^{i},\\quad i=1,\\ldots ,n}"},{"type":"math_alttext","value":"{\\displaystyle \\mathbf {e} ^{i}(\\mathbf {e} _{j})=\\delta _{j}^{i}}"}]
modifiedBi-orthogonality property932adb08a507
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anchors[{"section":"Finite-dimensional case","snippet":"is referred to as the bi-orthogonality property"},{"type":"math_alttext","value":"{\\displaystyle \\mathbf {e} ^{i}(c^{1}\\mathbf {e} _{1}+\\cdots +c^{n}\\mathbf {e} _{n})=c^{i},\\quad i=1,\\ldots ,n}"},{"type":"math_alttext","value":"{\\displaystyle \\mathbf {e} ^{i}(\\mathbf {e} _{j})=\\delta _{j}^{i}}"}]
modifiedVerifying a dual basis36dbb0166517
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anchors[{"section":"Finite-dimensional case","snippet":"These are a basis of"},{"type":"math_alttext","value":"{\\displaystyle g(x)=g(\\alpha _{1}\\mathbf {e} _{1}+\\dots +\\alpha _{n}\\mathbf {e} _{n})=\\alpha _{1}g(\\mathbf {e} _{1})+\\dots +\\alpha _{n}g(\\mathbf {e} _{n})=\\mathbf {e} ^{1}(x)g(\\mathbf {e} _{1})+\\dots +\\mathbf {e} ^{n}(x)g(\\mathbf {e} _{n})}"}]
modifiedDual basis of a non-orthogonal basis of R^26516474f1215
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anchors[{"section":"Finite-dimensional case","snippet":"let its basis be chosen as"},{"type":"math_alttext","value":"{\\displaystyle {\\begin{bmatrix}e^{11}&e^{12}\\\\e^{21}&e^{22}\\end{bmatrix}}{\\begin{bmatrix}e_{11}&e_{21}\\\\e_{12}&e_{22}\\end{bmatrix}}={\\begin{bmatrix}1&0\\\\0&1\\end{bmatrix}}.}"}]
modifiedMatrix biorthogonality of basis and dual basisfc077aacb3f1
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anchors[{"section":"Finite-dimensional case","snippet":"is a matrix whose columns are the basis vectors and"},{"type":"math_alttext","value":"{\\displaystyle {\\hat {E}}^{\\textrm {T}}\\cdot E=I_{n},}"}]
modifiedErdős–Kaplansky theoreme7ae04001119
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anchors[{"section":"Infinite-dimensional case","snippet":"The exact dimension of the dual is given by the Erdős–Kaplansky theorem"},{"type":"math_alttext","value":"{\\displaystyle \\mathrm {dim} (V)=|A|<|F|^{|A|}=|V^{\\ast }|=\\mathrm {max} (|\\mathrm {dim} (V^{\\ast })|,|F|),}"}]
modifiedTranspose of a linear map239ed389a53a
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anchors[{"section":"Transpose of a linear map","snippet":"then the transpose (or dual )"},{"type":"math_alttext","value":"{\\displaystyle f^{*}(\\varphi )=\\varphi \\circ f\\,}"}]
modifiedIdentity characterizing the transpose5386a7d60e33
FieldFrom #2560To #3168
anchors[{"section":"Transpose of a linear map","snippet":"This identity characterizes the transpose"},{"type":"math_alttext","value":"{\\displaystyle [f^{*}(\\varphi ),\\,v]=[\\varphi ,\\,f(v)],}"}]
modifiedBasic annihilator properties0869f6a8436c
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anchors[{"section":"Quotient spaces and annihilators","snippet":"The annihilator of a subset is itself a vector space."},{"type":"math_alttext","value":"{\\displaystyle \\{0\\}\\subseteq T^{0}\\subseteq S^{0}\\subseteq V^{*}.}"}]
modifiedAnnihilators of subsets, sums and intersectionsee181e1a2559
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anchors[{"section":"Quotient spaces and annihilators","snippet":"are two subsets of"},{"type":"math_alttext","value":"{\\displaystyle A^{0}+B^{0}\\subseteq (A\\cap B)^{0}.}"},{"type":"math_alttext","value":"{\\displaystyle \\left(\\bigcup _{i\\in I}A_{i}\\right)^{0}=\\bigcap _{i\\in I}A_{i}^{0}.}"},{"type":"math_alttext","value":"{\\displaystyle (A+B)^{0}=A^{0}\\cap B^{0}}"},{"type":"math_alttext","value":"{\\displaystyle (A\\cap B)^{0}=A^{0}+B^{0}.}"}]
modifiedDouble annihilator and Galois connection (finite-dim)0454ae75fbe7
FieldFrom #2560To #3168
anchors[{"section":"Quotient spaces and annihilators","snippet":"forming the annihilator is a Galois connection on the lattice of subsets"},{"type":"math_alttext","value":"{\\displaystyle W^{00}=W}"}]
modifiedContinuous dual space134d9935446c
FieldFrom #2560To #3168
mathlib.moduleMathlib.Topology.Algebra.Module.LinearMapMathlib.Topology.Algebra.Module.ContinuousLinearMap.Basic
modifiedPolar topology on the continuous dualdd2526394bcb
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mathlib.moduleMathlib.Analysis.Normed.Module.DualMathlib.Analysis.LocallyConvex.Polar
modifiedStrong topology2505a05f94e5
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mathlib.moduleMathlib.Topology.Algebra.Module.LinearMapMathlib.Topology.Algebra.Module.ContinuousLinearMap.Basic
modifiedStrong topology is normed for normed spaces798a0dc021a7
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anchors[{"section":"Topologies on the dual","snippet":"is normed (in fact a Banach space if the field of scalars is complete)"},{"type":"math_alttext","value":"{\\displaystyle \\|\\varphi \\|=\\sup _{\\|x\\|\\leq 1}|\\varphi (x)|.}"}]
modifiedDuals of quotient and subspace via annihilator560496a1e028
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anchors[{"section":"Annihilators","snippet":"Then, the dual of the quotient"},{"type":"math_alttext","value":"{\\displaystyle \\ker(j')=W^{\\perp }}"}]
addedDouble dual spacef5862c895cc2
addedTranspose is an antihomomorphism of algebras4125652eae81
addedAnnihilator reverses inclusions840c89c902ad