Normed (semi)groups #
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In this file we define 10 classes:
has_norm
,has_nnnorm
: auxiliary classes endowing a typeα
with a functionnorm : α → ℝ
(notation:‖x‖
) andnnnorm : α → ℝ≥0
(notation:‖x‖₊
), respectively;seminormed_..._group
: A seminormed (additive) (commutative) group is an (additive) (commutative) group with a norm and a compatible pseudometric space structure:∀ x y, dist x y = ‖x / y‖
or∀ x y, dist x y = ‖x - y‖
, depending on the group operation.normed_..._group
: A normed (additive) (commutative) group is an (additive) (commutative) group with a norm and a compatible metric space structure.
We also prove basic properties of (semi)normed groups and provide some instances.
Notes #
The current convention dist x y = ‖x - y‖
means that the distance is invariant under right
addition, but actions in mathlib are usually from the left. This means we might want to change it to
dist x y = ‖-x + y‖
.
The normed group hierarchy would lend itself well to a mixin design (that is, having
seminormed_group
and seminormed_add_group
not extend group
and add_group
), but we choose not
to for performance concerns.
Tags #
normed group
Auxiliary class, endowing a type E
with a function norm : E → ℝ
with notation ‖x‖
. This
class is designed to be extended in more interesting classes specifying the properties of the norm.
Instances of this typeclass
- seminormed_add_group.to_has_norm
- seminormed_group.to_has_norm
- normed_add_group.to_has_norm
- normed_group.to_has_norm
- seminormed_add_comm_group.to_has_norm
- seminormed_comm_group.to_has_norm
- normed_add_comm_group.to_has_norm
- normed_comm_group.to_has_norm
- non_unital_semi_normed_ring.to_has_norm
- semi_normed_ring.to_has_norm
- non_unital_normed_ring.to_has_norm
- normed_ring.to_has_norm
- normed_division_ring.to_has_norm
- normed_field.to_has_norm
- normed_ordered_add_group.to_has_norm
- normed_ordered_group.to_has_norm
- normed_linear_ordered_add_group.to_has_norm
- normed_linear_ordered_group.to_has_norm
- normed_linear_ordered_field.to_has_norm
- real.has_norm
- ulift.has_norm
- additive.has_norm
- multiplicative.has_norm
- order_dual.has_norm
- prod.has_norm
- normed_add_group_hom.has_op_norm
- complex.has_norm
- uniform_space.completion.has_norm
- continuous_linear_map.has_op_norm
- continuous_multilinear_map.has_op_norm
- continuous_multilinear_map.has_op_norm'
- norm_on_quotient
- pi_Lp.has_norm
- bounded_continuous_function.has_norm
- continuous_map.has_norm
- measure_theory.Lp.has_norm
- continuous_affine_map.has_norm
- lp.has_norm
- padic.has_norm
- padic_int.has_norm
- hamming.has_norm
Instances of other typeclasses for has_norm
- has_norm.has_sizeof_inst
Auxiliary class, endowing a type α
with a function nnnorm : α → ℝ≥0
with notation ‖x‖₊
.
Instances of this typeclass
Instances of other typeclasses for has_nnnorm
- has_nnnorm.has_sizeof_inst
- to_has_norm : has_norm E
- to_add_group : add_group E
- to_pseudo_metric_space : pseudo_metric_space E
- dist_eq : (∀ (x y : E), has_dist.dist x y = ‖x - y‖) . "obviously"
A seminormed group is an additive group endowed with a norm for which dist x y = ‖x - y‖
defines a pseudometric space structure.
Instances of this typeclass
Instances of other typeclasses for seminormed_add_group
- seminormed_add_group.has_sizeof_inst
- to_has_norm : has_norm E
- to_group : group E
- to_pseudo_metric_space : pseudo_metric_space E
- dist_eq : (∀ (x y : E), has_dist.dist x y = ‖x / y‖) . "obviously"
A seminormed group is a group endowed with a norm for which dist x y = ‖x / y‖
defines a
pseudometric space structure.
Instances of this typeclass
Instances of other typeclasses for seminormed_group
- seminormed_group.has_sizeof_inst
- to_has_norm : has_norm E
- to_add_group : add_group E
- to_metric_space : metric_space E
- dist_eq : (∀ (x y : E), has_dist.dist x y = ‖x - y‖) . "obviously"
A normed group is an additive group endowed with a norm for which dist x y = ‖x - y‖
defines a
metric space structure.
Instances of this typeclass
Instances of other typeclasses for normed_add_group
- normed_add_group.has_sizeof_inst
- to_has_norm : has_norm E
- to_group : group E
- to_metric_space : metric_space E
- dist_eq : (∀ (x y : E), has_dist.dist x y = ‖x / y‖) . "obviously"
A normed group is a group endowed with a norm for which dist x y = ‖x / y‖
defines a metric
space structure.
Instances of this typeclass
Instances of other typeclasses for normed_group
- normed_group.has_sizeof_inst
- to_has_norm : has_norm E
- to_add_comm_group : add_comm_group E
- to_pseudo_metric_space : pseudo_metric_space E
- dist_eq : (∀ (x y : E), has_dist.dist x y = ‖x - y‖) . "obviously"
A seminormed group is an additive group endowed with a norm for which dist x y = ‖x - y‖
defines a pseudometric space structure.
Instances of this typeclass
- normed_add_comm_group.to_seminormed_add_comm_group
- order_dual.seminormed_add_comm_group
- non_unital_semi_normed_ring.to_seminormed_add_comm_group
- ulift.seminormed_add_comm_group
- additive.seminormed_add_comm_group
- prod.seminormed_add_comm_group
- pi.seminormed_add_comm_group
- mul_opposite.seminormed_add_comm_group
- add_subgroup.seminormed_add_comm_group
- submodule.seminormed_add_comm_group
- normed_add_group_hom.to_seminormed_add_comm_group
- restrict_scalars.seminormed_add_comm_group
- continuous_linear_map.to_seminormed_add_comm_group
- add_subgroup.seminormed_add_comm_group_quotient
- submodule.quotient.seminormed_add_comm_group
- pi_Lp.seminormed_add_comm_group
- bounded_continuous_function.seminormed_add_comm_group
- normed_space.dual.seminormed_add_comm_group
- SemiNormedGroup.seminormed_add_comm_group
- SemiNormedGroup₁.seminormed_add_comm_group
- hamming.seminormed_add_comm_group
Instances of other typeclasses for seminormed_add_comm_group
- seminormed_add_comm_group.has_sizeof_inst
- to_has_norm : has_norm E
- to_comm_group : comm_group E
- to_pseudo_metric_space : pseudo_metric_space E
- dist_eq : (∀ (x y : E), has_dist.dist x y = ‖x / y‖) . "obviously"
A seminormed group is a group endowed with a norm for which dist x y = ‖x / y‖
defines a pseudometric space structure.
Instances of this typeclass
Instances of other typeclasses for seminormed_comm_group
- seminormed_comm_group.has_sizeof_inst
- to_has_norm : has_norm E
- to_add_comm_group : add_comm_group E
- to_metric_space : metric_space E
- dist_eq : (∀ (x y : E), has_dist.dist x y = ‖x - y‖) . "obviously"
A normed group is an additive group endowed with a norm for which dist x y = ‖x - y‖
defines a
metric space structure.
Instances of this typeclass
- order_dual.normed_add_comm_group
- non_unital_normed_ring.to_normed_add_comm_group
- normed_ordered_add_group.to_normed_add_comm_group
- normed_lattice_add_comm_group.to_normed_add_comm_group
- punit.normed_add_comm_group
- real.normed_add_comm_group
- int.normed_add_comm_group
- rat.normed_add_comm_group
- ulift.normed_add_comm_group
- additive.normed_add_comm_group
- prod.normed_add_comm_group
- pi.normed_add_comm_group
- mul_opposite.normed_add_comm_group
- add_subgroup.normed_add_comm_group
- submodule.normed_add_comm_group
- normed_add_group_hom.to_normed_add_comm_group
- restrict_scalars.normed_add_comm_group
- complex.normed_add_comm_group
- uniform_space.completion.normed_add_comm_group
- continuous_linear_map.to_normed_add_comm_group
- continuous_multilinear_map.normed_add_comm_group
- continuous_multilinear_map.normed_add_comm_group'
- add_subgroup.normed_add_comm_group_quotient
- submodule.quotient.normed_add_comm_group
- add_circle.normed_add_comm_group
- real.angle.normed_add_comm_group
- pi_Lp.normed_add_comm_group
- bounded_continuous_function.normed_add_comm_group
- continuous_map.normed_add_comm_group
- measure_theory.Lp.normed_add_comm_group
- normed_space.dual.normed_add_comm_group
- continuous_affine_map.normed_add_comm_group
- zero_at_infty_continuous_map.normed_add_comm_group
- lp.normed_add_comm_group
- quaternion.normed_add_comm_group
- enorm.finite_subspace.normed_add_comm_group
- hamming.normed_add_comm_group
Instances of other typeclasses for normed_add_comm_group
- normed_add_comm_group.has_sizeof_inst
- to_has_norm : has_norm E
- to_comm_group : comm_group E
- to_metric_space : metric_space E
- dist_eq : (∀ (x y : E), has_dist.dist x y = ‖x / y‖) . "obviously"
A normed group is a group endowed with a norm for which dist x y = ‖x / y‖
defines a metric
space structure.
Instances of this typeclass
Instances of other typeclasses for normed_comm_group
- normed_comm_group.has_sizeof_inst
Equations
Equations
Equations
- seminormed_add_comm_group.to_seminormed_add_group = {to_has_norm := seminormed_add_comm_group.to_has_norm _inst_1, to_add_group := {add := add_comm_group.add seminormed_add_comm_group.to_add_comm_group, add_assoc := _, zero := add_comm_group.zero seminormed_add_comm_group.to_add_comm_group, zero_add := _, add_zero := _, nsmul := add_comm_group.nsmul seminormed_add_comm_group.to_add_comm_group, nsmul_zero' := _, nsmul_succ' := _, neg := add_comm_group.neg seminormed_add_comm_group.to_add_comm_group, sub := add_comm_group.sub seminormed_add_comm_group.to_add_comm_group, sub_eq_add_neg := _, zsmul := add_comm_group.zsmul seminormed_add_comm_group.to_add_comm_group, zsmul_zero' := _, zsmul_succ' := _, zsmul_neg' := _, add_left_neg := _}, to_pseudo_metric_space := seminormed_add_comm_group.to_pseudo_metric_space _inst_1, dist_eq := _}
Equations
- seminormed_comm_group.to_seminormed_group = {to_has_norm := seminormed_comm_group.to_has_norm _inst_1, to_group := {mul := comm_group.mul seminormed_comm_group.to_comm_group, mul_assoc := _, one := comm_group.one seminormed_comm_group.to_comm_group, one_mul := _, mul_one := _, npow := comm_group.npow seminormed_comm_group.to_comm_group, npow_zero' := _, npow_succ' := _, inv := comm_group.inv seminormed_comm_group.to_comm_group, div := comm_group.div seminormed_comm_group.to_comm_group, div_eq_mul_inv := _, zpow := comm_group.zpow seminormed_comm_group.to_comm_group, zpow_zero' := _, zpow_succ' := _, zpow_neg' := _, mul_left_inv := _}, to_pseudo_metric_space := seminormed_comm_group.to_pseudo_metric_space _inst_1, dist_eq := _}
Equations
- normed_comm_group.to_normed_group = {to_has_norm := normed_comm_group.to_has_norm _inst_1, to_group := {mul := comm_group.mul normed_comm_group.to_comm_group, mul_assoc := _, one := comm_group.one normed_comm_group.to_comm_group, one_mul := _, mul_one := _, npow := comm_group.npow normed_comm_group.to_comm_group, npow_zero' := _, npow_succ' := _, inv := comm_group.inv normed_comm_group.to_comm_group, div := comm_group.div normed_comm_group.to_comm_group, div_eq_mul_inv := _, zpow := comm_group.zpow normed_comm_group.to_comm_group, zpow_zero' := _, zpow_succ' := _, zpow_neg' := _, mul_left_inv := _}, to_metric_space := normed_comm_group.to_metric_space _inst_1, dist_eq := _}
Equations
- normed_add_comm_group.to_normed_add_group = {to_has_norm := normed_add_comm_group.to_has_norm _inst_1, to_add_group := {add := add_comm_group.add normed_add_comm_group.to_add_comm_group, add_assoc := _, zero := add_comm_group.zero normed_add_comm_group.to_add_comm_group, zero_add := _, add_zero := _, nsmul := add_comm_group.nsmul normed_add_comm_group.to_add_comm_group, nsmul_zero' := _, nsmul_succ' := _, neg := add_comm_group.neg normed_add_comm_group.to_add_comm_group, sub := add_comm_group.sub normed_add_comm_group.to_add_comm_group, sub_eq_add_neg := _, zsmul := add_comm_group.zsmul normed_add_comm_group.to_add_comm_group, zsmul_zero' := _, zsmul_succ' := _, zsmul_neg' := _, add_left_neg := _}, to_metric_space := normed_add_comm_group.to_metric_space _inst_1, dist_eq := _}
Construct a normed_group
from a seminormed_group
satisfying ∀ x, ‖x‖ = 0 → x = 1
. This
avoids having to go back to the (pseudo_)metric_space
level when declaring a normed_group
instance as a special case of a more general seminormed_group
instance.
Equations
- normed_group.of_separation h = {to_has_norm := seminormed_group.to_has_norm _inst_1, to_group := seminormed_group.to_group _inst_1, to_metric_space := {to_pseudo_metric_space := seminormed_group.to_pseudo_metric_space _inst_1, eq_of_dist_eq_zero := _}, dist_eq := _}
Construct a normed_add_group
from a seminormed_add_group
satisfying
∀ x, ‖x‖ = 0 → x = 0
. This avoids having to go back to the (pseudo_)metric_space
level when
declaring a normed_add_group
instance as a special case of a more general seminormed_add_group
instance.
Equations
- normed_add_group.of_separation h = {to_has_norm := seminormed_add_group.to_has_norm _inst_1, to_add_group := seminormed_add_group.to_add_group _inst_1, to_metric_space := {to_pseudo_metric_space := seminormed_add_group.to_pseudo_metric_space _inst_1, eq_of_dist_eq_zero := _}, dist_eq := _}
Construct a normed_add_comm_group
from a seminormed_add_comm_group
satisfying
∀ x, ‖x‖ = 0 → x = 0
. This avoids having to go back to the (pseudo_)metric_space
level when
declaring a normed_add_comm_group
instance as a special case of a more general
seminormed_add_comm_group
instance.
Equations
Construct a normed_comm_group
from a seminormed_comm_group
satisfying
∀ x, ‖x‖ = 0 → x = 1
. This avoids having to go back to the (pseudo_)metric_space
level when
declaring a normed_comm_group
instance as a special case of a more general seminormed_comm_group
instance.
Equations
Construct a seminormed group from a translation-invariant distance.
Equations
- seminormed_add_group.of_add_dist h₁ h₂ = {to_has_norm := _inst_1, to_add_group := _inst_2, to_pseudo_metric_space := _inst_3, dist_eq := _}
Construct a seminormed group from a multiplication-invariant distance.
Equations
- seminormed_group.of_mul_dist h₁ h₂ = {to_has_norm := _inst_1, to_group := _inst_2, to_pseudo_metric_space := _inst_3, dist_eq := _}
Construct a seminormed group from a translation-invariant pseudodistance.
Equations
- seminormed_add_group.of_add_dist' h₁ h₂ = {to_has_norm := _inst_1, to_add_group := _inst_2, to_pseudo_metric_space := _inst_3, dist_eq := _}
Construct a seminormed group from a multiplication-invariant pseudodistance.
Equations
- seminormed_group.of_mul_dist' h₁ h₂ = {to_has_norm := _inst_1, to_group := _inst_2, to_pseudo_metric_space := _inst_3, dist_eq := _}
Construct a seminormed group from a translation-invariant pseudodistance.
Equations
Construct a seminormed group from a multiplication-invariant pseudodistance.
Equations
- seminormed_comm_group.of_mul_dist h₁ h₂ = {to_has_norm := seminormed_group.to_has_norm (seminormed_group.of_mul_dist h₁ h₂), to_comm_group := _inst_2, to_pseudo_metric_space := seminormed_group.to_pseudo_metric_space (seminormed_group.of_mul_dist h₁ h₂), dist_eq := _}
Construct a seminormed group from a multiplication-invariant pseudodistance.
Equations
- seminormed_comm_group.of_mul_dist' h₁ h₂ = {to_has_norm := seminormed_group.to_has_norm (seminormed_group.of_mul_dist' h₁ h₂), to_comm_group := _inst_2, to_pseudo_metric_space := seminormed_group.to_pseudo_metric_space (seminormed_group.of_mul_dist' h₁ h₂), dist_eq := _}
Construct a seminormed group from a translation-invariant pseudodistance.
Equations
Construct a normed group from a multiplication-invariant distance.
Equations
- normed_group.of_mul_dist h₁ h₂ = {to_has_norm := seminormed_group.to_has_norm (seminormed_group.of_mul_dist h₁ h₂), to_group := seminormed_group.to_group (seminormed_group.of_mul_dist h₁ h₂), to_metric_space := _inst_3, dist_eq := _}
Construct a normed group from a translation-invariant distance.
Equations
- normed_add_group.of_add_dist h₁ h₂ = {to_has_norm := seminormed_add_group.to_has_norm (seminormed_add_group.of_add_dist h₁ h₂), to_add_group := seminormed_add_group.to_add_group (seminormed_add_group.of_add_dist h₁ h₂), to_metric_space := _inst_3, dist_eq := _}
Construct a normed group from a translation-invariant pseudodistance.
Equations
- normed_add_group.of_add_dist' h₁ h₂ = {to_has_norm := seminormed_add_group.to_has_norm (seminormed_add_group.of_add_dist' h₁ h₂), to_add_group := seminormed_add_group.to_add_group (seminormed_add_group.of_add_dist' h₁ h₂), to_metric_space := _inst_3, dist_eq := _}
Construct a normed group from a multiplication-invariant pseudodistance.
Equations
- normed_group.of_mul_dist' h₁ h₂ = {to_has_norm := seminormed_group.to_has_norm (seminormed_group.of_mul_dist' h₁ h₂), to_group := seminormed_group.to_group (seminormed_group.of_mul_dist' h₁ h₂), to_metric_space := _inst_3, dist_eq := _}
Construct a normed group from a multiplication-invariant pseudodistance.
Equations
- normed_comm_group.of_mul_dist h₁ h₂ = {to_has_norm := normed_group.to_has_norm (normed_group.of_mul_dist h₁ h₂), to_comm_group := _inst_2, to_metric_space := normed_group.to_metric_space (normed_group.of_mul_dist h₁ h₂), dist_eq := _}
Construct a normed group from a translation-invariant pseudodistance.
Equations
- normed_add_comm_group.of_add_dist h₁ h₂ = {to_has_norm := normed_add_group.to_has_norm (normed_add_group.of_add_dist h₁ h₂), to_add_comm_group := _inst_2, to_metric_space := normed_add_group.to_metric_space (normed_add_group.of_add_dist h₁ h₂), dist_eq := _}
Construct a normed group from a translation-invariant pseudodistance.
Equations
- normed_add_comm_group.of_add_dist' h₁ h₂ = {to_has_norm := normed_add_group.to_has_norm (normed_add_group.of_add_dist' h₁ h₂), to_add_comm_group := _inst_2, to_metric_space := normed_add_group.to_metric_space (normed_add_group.of_add_dist' h₁ h₂), dist_eq := _}
Construct a normed group from a multiplication-invariant pseudodistance.
Equations
- normed_comm_group.of_mul_dist' h₁ h₂ = {to_has_norm := normed_group.to_has_norm (normed_group.of_mul_dist' h₁ h₂), to_comm_group := _inst_2, to_metric_space := normed_group.to_metric_space (normed_group.of_mul_dist' h₁ h₂), dist_eq := _}
Construct a seminormed group from a seminorm, i.e., registering the pseudodistance*
and the pseudometric space structure from the seminorm properties. Note that in most cases this
instance creates bad definitional equalities (e.g., it does not take into account a possibly
existing uniform_space
instance on E
).
Equations
- f.to_seminormed_add_group = {to_has_norm := {norm := ⇑f}, to_add_group := _inst_1, to_pseudo_metric_space := {to_has_dist := {dist := λ (x y : E), ⇑f (x - y)}, dist_self := _, dist_comm := _, dist_triangle := _, edist := λ (x y : E), ↑⟨has_dist.dist x y, _⟩, edist_dist := _, to_uniform_space := uniform_space_of_dist has_dist.dist _ _ _, uniformity_dist := _, to_bornology := bornology.of_dist has_dist.dist _ _ _, cobounded_sets := _}, dist_eq := _}
Construct a seminormed group from a seminorm, i.e., registering the pseudodistance and the
pseudometric space structure from the seminorm properties. Note that in most cases this instance
creates bad definitional equalities (e.g., it does not take into account a possibly existing
uniform_space
instance on E
).
Equations
- f.to_seminormed_group = {to_has_norm := {norm := ⇑f}, to_group := _inst_1, to_pseudo_metric_space := {to_has_dist := {dist := λ (x y : E), ⇑f (x / y)}, dist_self := _, dist_comm := _, dist_triangle := _, edist := λ (x y : E), ↑⟨has_dist.dist x y, _⟩, edist_dist := _, to_uniform_space := uniform_space_of_dist has_dist.dist _ _ _, uniformity_dist := _, to_bornology := bornology.of_dist has_dist.dist _ _ _, cobounded_sets := _}, dist_eq := _}
Construct a seminormed group from a seminorm, i.e., registering the pseudodistance and the
pseudometric space structure from the seminorm properties. Note that in most cases this instance
creates bad definitional equalities (e.g., it does not take into account a possibly existing
uniform_space
instance on E
).
Equations
Construct a seminormed group from a seminorm, i.e., registering the pseudodistance*
and the pseudometric space structure from the seminorm properties. Note that in most cases this
instance creates bad definitional equalities (e.g., it does not take into account a possibly
existing uniform_space
instance on E
).
Construct a normed group from a norm, i.e., registering the distance and the metric space
structure from the norm properties. Note that in most cases this instance creates bad definitional
equalities (e.g., it does not take into account a possibly existing uniform_space
instance on
E
).
Equations
- f.to_normed_group = {to_has_norm := seminormed_group.to_has_norm f.to_group_seminorm.to_seminormed_group, to_group := seminormed_group.to_group f.to_group_seminorm.to_seminormed_group, to_metric_space := {to_pseudo_metric_space := seminormed_group.to_pseudo_metric_space f.to_group_seminorm.to_seminormed_group, eq_of_dist_eq_zero := _}, dist_eq := _}
Construct a normed group from a norm, i.e., registering the distance and the metric
space structure from the norm properties. Note that in most cases this instance creates bad
definitional equalities (e.g., it does not take into account a possibly existing uniform_space
instance on E
).
Equations
- f.to_normed_add_group = {to_has_norm := seminormed_add_group.to_has_norm f.to_add_group_seminorm.to_seminormed_add_group, to_add_group := seminormed_add_group.to_add_group f.to_add_group_seminorm.to_seminormed_add_group, to_metric_space := {to_pseudo_metric_space := seminormed_add_group.to_pseudo_metric_space f.to_add_group_seminorm.to_seminormed_add_group, eq_of_dist_eq_zero := _}, dist_eq := _}
Construct a normed group from a norm, i.e., registering the distance and the metric
space structure from the norm properties. Note that in most cases this instance creates bad
definitional equalities (e.g., it does not take into account a possibly existing uniform_space
instance on E
).
Equations
Construct a normed group from a norm, i.e., registering the distance and the metric space
structure from the norm properties. Note that in most cases this instance creates bad definitional
equalities (e.g., it does not take into account a possibly existing uniform_space
instance on
E
).
Equations
- f.to_normed_comm_group = {to_has_norm := normed_group.to_has_norm f.to_normed_group, to_comm_group := _inst_1, to_metric_space := normed_group.to_metric_space f.to_normed_group, dist_eq := _}
Equations
- punit.normed_add_comm_group = {to_has_norm := {norm := function.const punit 0}, to_add_comm_group := punit.add_comm_group, to_metric_space := punit.metric_space, dist_eq := punit.normed_add_comm_group._proof_1}
Alias of dist_eq_norm_sub
.
Alias of dist_eq_norm_sub'
.
In a (semi)normed group, inversion x ↦ x⁻¹
tends to infinity at infinity. TODO: use
bornology.cobounded
instead of filter.comap has_norm.norm filter.at_top
.
In a (semi)normed group, negation x ↦ -x
tends to infinity at infinity. TODO: use
bornology.cobounded
instead of filter.comap has_norm.norm filter.at_top
.
Alias of norm_le_norm_add_norm_sub
.
Alias of the forward direction of bounded_iff_forall_norm_le
.
The norm of a seminormed group as a group seminorm.
Equations
- norm_group_seminorm E = {to_fun := has_norm.norm seminormed_group.to_has_norm, map_one' := _, mul_le' := _, inv' := _}
The norm of a seminormed group as an additive group seminorm.
Equations
- norm_add_group_seminorm E = {to_fun := has_norm.norm seminormed_add_group.to_has_norm, map_zero' := _, add_le' := _, neg' := _}
A homomorphism f
of seminormed groups is Lipschitz, if there exists a constant C
such that
for all x
, one has ‖f x‖ ≤ C * ‖x‖
. The analogous condition for a linear map of
(semi)normed spaces is in normed_space.operator_norm
.
A homomorphism f
of seminormed groups is Lipschitz, if there exists a constant C
such that for all x
, one has ‖f x‖ ≤ C * ‖x‖
. The analogous condition for a linear map of
(semi)normed spaces is in normed_space.operator_norm
.
Alias of the forward direction of lipschitz_on_with_iff_norm_div_le
.
Alias of the forward direction of lipschitz_on_with_iff_norm_div_le
.
Alias of the forward direction of lipschitz_with_iff_norm_div_le
.
Alias of the forward direction of lipschitz_with_iff_norm_div_le
.
A homomorphism f
of seminormed groups is continuous, if there exists a constant C
such that
for all x
, one has ‖f x‖ ≤ C * ‖x‖
.
A homomorphism f
of seminormed groups is continuous, if there exists a constant C
such that for all x
, one has ‖f x‖ ≤ C * ‖x‖
Alias of the reverse direction of monoid_hom_class.isometry_iff_norm
.
Alias of the reverse direction of monoid_hom_class.isometry_iff_norm
.
Alias of nndist_eq_nnnorm_sub
.
Alias of nnnorm_le_nnnorm_add_nnnorm_sub
.
Special case of the sandwich theorem: if the norm of f
is eventually bounded by a real
function a
which tends to 0
, then f
tends to 1
. In this pair of lemmas (squeeze_one_norm'
and squeeze_one_norm
), following a convention of similar lemmas in topology.metric_space.basic
and topology.algebra.order
, the '
version is phrased using "eventually" and the non-'
version
is phrased absolutely.
Special case of the sandwich theorem: if the norm of f
is eventually bounded by a
real function a
which tends to 0
, then f
tends to 1
. In this pair of lemmas
(squeeze_zero_norm'
and squeeze_zero_norm
), following a convention of similar lemmas in
topology.metric_space.basic
and topology.algebra.order
, the '
version is phrased using
"eventually" and the non-'
version is phrased absolutely.
Special case of the sandwich theorem: if the norm of f
is bounded by a real
function a
which tends to 0
, then f
tends to 0
.
Special case of the sandwich theorem: if the norm of f
is bounded by a real function a
which
tends to 0
, then f
tends to 1
.
A helper lemma used to prove that the (scalar or usual) product of a function that
tends to zero and a bounded function tends to zero. This lemma is formulated for any binary
operation op : E → F → G
with an estimate ‖op x y‖ ≤ A * ‖x‖ * ‖y‖
for some constant A instead
of multiplication so that it can be applied to (*)
, flip (*)
, (•)
, and flip (•)
.
A helper lemma used to prove that the (scalar or usual) product of a function that tends to one
and a bounded function tends to one. This lemma is formulated for any binary operation
op : E → F → G
with an estimate ‖op x y‖ ≤ A * ‖x‖ * ‖y‖
for some constant A instead of
multiplication so that it can be applied to (*)
, flip (*)
, (•)
, and flip (•)
.
A helper lemma used to prove that the (scalar or usual) product of a function that tends to one
and a bounded function tends to one. This lemma is formulated for any binary operation
op : E → F → G
with an estimate ‖op x y‖ ≤ ‖x‖ * ‖y‖
instead of multiplication so that it
can be applied to (*)
, flip (*)
, (•)
, and flip (•)
.
A helper lemma used to prove that the (scalar or usual) product of a function that
tends to zero and a bounded function tends to zero. This lemma is formulated for any binary
operation op : E → F → G
with an estimate ‖op x y‖ ≤ ‖x‖ * ‖y‖
instead of multiplication so that
it can be applied to (*)
, flip (*)
, (•)
, and flip (•)
.
If ‖y‖→∞
, then we can assume y≠x
for any
fixed x
If ‖y‖ → ∞
, then we can assume y ≠ x
for any fixed x
.