Physlib.Mathematics.LinearPMap
LinearPMap
i. Overview
In this module we collect some basic results about `LinearPMap`s.
Most important is the definition of restricted composition. The composition of two partial linear maps `g : F →ₗ.[R] G` and `f : E →ₗ.[R] F` is defined only if the range of `f` is contained in the domain of `g` (c.f. `LinearPMap.comp`). `g.compRestricted f` (`g ∘ᵣ f`) is defined to be the composition of `g` with the restriction of `f` to exactly those `x : f.domain` for which `f x ∈ g.domain`. This allows one to work with the composition of partial linear maps while having the domain implicitly accounted for.
ii. Key results
- `LinearPMap.sum` : The finite sum of partial linear maps. - `LinearPMap.compRestricted` (`∘ᵣ`) : For two partial linear maps `g : F →ₗ[R] G` and `f : E →ₗ[R] F`, the composition of `g` with `f` with natural domain `{x : f.domain | f x ∈ g.domain}`. - `LinearPMap.instMonoid` : Partial linear maps `E →ₗ.[R] E` with `compRestricted` for multiplication and the identity map for `1` comprise a monoid.
iii. Table of contents
- A. Inequalities
- B. Zero smul
- C. Finite sums
- D. Restricted composition
- E. Monoid
- F. Inverses
iv. References
A. Inequalities
B. Zero smul
C. Finite sums
D. Restricted composition
E. Monoid
Partial linear maps `E →ₗ.[R] E` with `compRestricted` for multiplication and the identity map (domain `⊤`) for `1` comprise a monoid.
F. Inverses
55 declarations
for partial linear maps
For any partial linear map , the difference of with itself is less than or equal to the zero partial linear map, i.e., . In the context of partial linear maps, the inequality means that the domain of is a subspace of the domain of and that and coincide on the domain of .
for partial linear maps
For any partial linear map , the sum of its negation and itself is less than or equal to the zero partial linear map, denoted as . In this context, the relation indicates that is an extension of (i.e., the domain of is a subspace of the domain of , and they coincide on the domain of ).
for partial linear maps
For any two partial linear maps and , the relation holds if and only if . Here, the relation denotes the extension of partial maps, where means that the domain of is a subspace of the domain of and the maps agree on the domain of .
For any two partial linear maps and , the relation holds if and only if holds. Here, the inequality denotes that the partial linear map is an extension of , and denotes the pointwise negation of the map.
for Partial Linear Maps
For any two partial linear maps and , the inequality holds. In this context, for partial linear maps and , the relation signifies that the domain of is a subspace of the domain of and coincides with on the domain of . The operations of addition and subtraction for partial linear maps are defined on the intersection of the domains of the operands.
for partial linear maps
For any partial linear maps and , the inequality holds. Here, the inequality for partial linear maps denotes that the domain of is a subspace of the domain of and the two maps agree on the domain of .
for partial linear maps
For any partial linear maps and , it holds that . In this context, the inequality denotes that is an extension of , meaning the domain of is a subspace of the domain of and for all in the domain of .
for partial linear maps
For partial linear maps , the inequality holds. In the context of partial linear maps, means that is an extension of (i.e., the domain of is a subset of the domain of and the maps agree on the domain of ).
for partial linear maps
For any partial linear maps and , the following inequality holds: where the inequality denotes that is an extension of (i.e., the domain of is a subspace of the domain of , and for all in the domain of ).
for partial linear maps
For any three partial linear maps and , it holds that . Here, the relation between partial linear maps signifies that the domain of is a subspace of the domain of and that for all in the domain of .
Left cancellation in nested subtractions for partial linear maps
For any partial linear maps , , and , the following inequality holds: where the subtraction of two partial linear maps is defined on the intersection of their domains, and the relation denotes that is a restriction of (i.e., the domain of is a subspace of the domain of and the maps agree on the domain of ).
for partial linear maps
Let , and be partial linear maps. If , then . Here, the inequality between partial linear maps indicates that the domain of is a subspace of the domain of and the maps coincide on the domain of .
for partial linear maps
For any partial linear maps and , the partial linear map is a restriction of , expressed as .
for partial linear maps
For any partial linear maps , and , if , then . (Here, the relation for partial linear maps denotes that the domain of the smaller map is a subspace of the domain of the larger map, and the maps coincide on the smaller domain).
for partial linear maps
Let and be partial linear maps. If , then . The relation for partial linear maps signifies that the domain of is a subspace of the domain of and the maps agree on the domain of .
for partial linear maps
Let , , and be partial linear maps. If (meaning the domain of is contained in the domain of and agrees with on the domain of ), then .
for partial linear maps
For any partial linear maps , , and , if , then . Here, the relation means that the domain of is a subspace of the domain of and is the restriction of to the domain of .
For any partial linear maps , , and , if , then . Here, the relation means that is an extension of ; that is, the domain of is a subspace of the domain of and for all in the domain of .
for partial linear maps
For any partial linear map over a scalar field , the scalar product of and is less than or equal to the zero partial linear map: In the context of partial linear maps, the relation means that the domain of is a subspace of the domain of and agrees with on that subspace.
for partial linear maps with full domain
Let be a partial linear map from to over a field . If the domain of is the entire space (denoted by ), then the scalar multiplication of by is equal to the zero partial linear map. That is, .
Finite sum of partial linear maps
Given a finite family of partial linear maps from a module to over a ring , the sum is a partial linear map . Its domain is defined as the intersection of the domains of all maps in the family, . The value of the sum at an element in this intersection is the sum of the values of each individual partial linear map, .
for partial linear maps
For a finite family of partial linear maps , the domain of their sum is the intersection of the domains of the individual maps . In mathematical notation, this is expressed as .
Given a finite family of partial linear maps , the domain of their sum is a submodule of the domain of each individual map for any .
for partial linear maps
For a finite family of partial linear maps and an element belonging to the domain of their sum , the value of the sum evaluated at is the sum of each map evaluated at : Note that belongs to the domain of the sum if and only if it belongs to the intersection of the domains of all individual maps .
Restricted composition of partial linear maps
Given partial linear maps and with domains and respectively, their restricted composition is the partial linear map from to whose domain consists of those such that . For such , the value is defined as .
Restricted composition notation for partial linear maps
The notation denotes the restricted composition of two partial linear maps and . If is a partial linear map from to and is a partial linear map from to , then is defined as the partial linear map whose domain consists of those in the domain of for which is in the domain of . The mapping is given by .
Let and be partial linear maps. The domain of their restricted composition is contained in the domain of , which is expressed as .
Domain of equals the inclusion of the preimage of under
Let and be partial linear maps with domains and . Let denote the linear map underlying , and let be the inclusion map. The domain of the restricted composition is the image under of the preimage of under :
Let and be partial linear maps. For any element , belongs to the domain of the restricted composition if and only if belongs to the domain of and its image belongs to the domain of .
Let , and be vector spaces over a ring . For partial linear maps and , an element is in the domain of the restricted composition if and only if there exists such that and there exists such that .
For partial linear maps and , if is an element of the domain of the restricted composition , then its image is contained in the domain of .
for partial linear maps
Let and be partial linear maps between modules over a ring . For any element in the domain of the restricted composition , the value of the composition is given by .
for partial linear maps
For any partial linear map between modules and over a ring , and for the zero partial linear map (whose domain is the entire module ), their restricted composition satisfies . Here, on the right-hand side denotes the zero partial linear map from to .
for partial linear maps
Let and be modules over a ring . For any partial linear maps , , and , the restricted composition is associative, meaning .
when the range of is contained in the domain of
Let , and be modules over a ring . Let and be partial linear maps. If for every in the domain of , the image is contained in the domain of , then the restricted composition is equal to the standard composition (denoted as `v.comp u h`).
Let and be modules over a ring . Let and be partial linear maps. For any submodule of , let denote the restriction of to the subdomain . If the image of is contained in the domain of (i.e., ), then the composition is less than or equal to the restricted composition . Here, means that and for all , and the restricted composition is the partial linear map with domain .
Left Monotonicity of Restricted Composition:
Let and be modules over a ring . Let be a partial linear map, and let be partial linear maps. If , then the restricted compositions satisfy . Here, denotes that the domain of is a submodule of the domain of and for all , and denotes the restricted composition.
Right Monotonicity of Restricted Composition:
Let and be modules over a ring . Let be a partial linear map, and let be partial linear maps. If , then the restricted compositions satisfy . Here, the relation means that the domain of is a submodule of the domain of and for all , and denotes the restricted composition.
Given partial linear maps and , the restricted composition of the negation of with is equal to the negation of the restricted composition of with , which is expressed as .
Let and be partial linear maps between modules over a ring . The restricted composition of with the negation of is equal to the negation of the restricted composition of and , that is, .
For partial linear maps and , the restricted composition of the sum with is equal to the sum of the restricted compositions of and with : where the restricted composition is the partial linear map with domain , and the sum of two partial linear maps has a domain equal to the intersection of their respective domains.
For partial linear maps and , the restricted composition of the difference with is equal to the difference of the restricted compositions: where the restricted composition is the partial linear map whose domain is .
for partial linear maps
For any partial linear maps from to and from to , the sum of the restricted compositions and is less than or equal to the restricted composition of with the sum : In the context of partial linear maps, the inequality means that the domain of is a subset of the domain of , and the maps agree on the domain of .
for partial linear maps
For any partial linear maps from to and from to , the difference of the restricted compositions of with and is less than or equal to the restricted composition of with the difference : where the inequality between partial linear maps signifies that is a restriction of (i.e., and for all ).
for non-zero
Let be a division ring and be modules over . Given partial linear maps and , and a non-zero scalar , the restricted composition of with the scalar multiple is equal to the scalar multiple of the restricted composition of with . That is, where the restricted composition of two partial linear maps is defined on the domain .
for partial linear maps
Let be a monoid and be modules over a ring . Suppose has a distributive action on that commutes with the action of . For any scalar and any partial linear maps and , the restricted composition of with is equal to the scalar multiple of the restricted composition of with : where the restricted composition is defined on the domain .
Monoid of partial linear maps under restricted composition
Let be a module over a ring . The set of partial linear maps from to itself forms a monoid. The multiplication operation is the restricted composition , whose domain is , and the identity element is the identity linear map defined on the entire space .
for partial linear maps
For any two partial linear maps from a module to itself, their product in the monoid of partial linear maps is equal to their restricted composition . The restricted composition is defined on the domain .
The domain of the identity partial linear map is
Let be a module over a ring . In the monoid of partial linear maps from to itself, the domain of the identity element is the entire module , denoted by .
The underlying linear map of the identity partial linear map is the canonical map from to .
Let be a module over a ring . The identity element in the monoid of partial linear maps from to itself (under restricted composition) is defined such that its underlying linear map is equal to the canonical linear map from the universal submodule of to .
The underlying function of the identity partial linear map is the identity map on
Let be a module over a ring . The function underlying the identity element in the monoid of partial linear maps from to itself is equal to the function of the linear map identifying the top submodule (the entire space ) with .
For any partial linear map , the kernel of its inverse partial linear map is the trivial subspace .
The inverse of the inverse of a partial linear map is
For any partial linear map , the inverse of the inverse of is equal to . A partial linear map is defined as a linear map whose domain is a submodule of the total space.
equals the identity map on the domain of
Let be a partial linear map with domain . The restricted composition of the inverse of and , denoted , is equal to the identity map restricted to .
equals the identity on the domain of
For any partial linear map , the restricted composition of with its inverse (denoted ) is equal to the identity map restricted to the domain of . That is, .
