ENorm.map_zero
theorem ENorm.map_zero :
ā {š : Type u_1} {V : Type u_2} [inst : NormedField š] [inst_1 : AddCommGroup V] [inst_2 : Module š V]
(e : ENorm š V), āe 0 = 0
This theorem states that for any field š with a norm (a NormedField), for any additive commutative group V, and for any module V over š, if e is an extended norm (ENorm) on V over š, then the value of e at the zero element of V is zero. In other words, the extended norm of zero is always zero, regardless of the particular field, additive group, or module in question.
More concisely: For any NormedField š, any additive commutative group V as a š-module, and any extended norm e on V, we have e(0) = 0.
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ENorm.map_add_le
theorem ENorm.map_add_le :
ā {š : Type u_1} {V : Type u_2} [inst : NormedField š] [inst_1 : AddCommGroup V] [inst_2 : Module š V]
(e : ENorm š V) (x y : V), āe (x + y) ⤠āe x + āe y
This theorem states that for any normed field `š`, an additive commutative group `V`, and a module over `š` and `V`, the extended norm `e` of the sum of two elements `x` and `y` from `V` is less than or equal to the sum of the extended norms of `x` and `y` individually. In other words, the extended norm has the property of subadditivity: `e(x + y) ⤠e(x) + e(y)`.
More concisely: For any normed field `š` and normed additive commutative group `V` with module `M`, the extended norm `e` on `V` is subadditive, that is, `e(x + y) ⤠e(x) + e(y)` for all `x, y ā V`.
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ENorm.map_smul
theorem ENorm.map_smul :
ā {š : Type u_1} {V : Type u_2} [inst : NormedField š] [inst_1 : AddCommGroup V] [inst_2 : Module š V]
(e : ENorm š V) (c : š) (x : V), āe (c ⢠x) = āācāā * āe x
This theorem states that for any normed field `š`, additively commutative group `V`, and `š`-module `V`, given an extended norm `e` on `V`, a scalar `c` from `š`, and a vector `x` from `V`, the extended norm of the scalar multiplication of `c` and `x` (`c ⢠x`) is equal to the product of the nonnegative norm (or absolute value) of `c` (`ācāā`) and the extended norm of `x`. In essence, it captures the principle that scaling a vector by a factor changes its norm by the absolute value of that factor.
More concisely: For any normed field `š`, additively commutative group `V`, and `š`-module `V` with extended norm `e`, the extended norm of scalar multiplication `e(c ⢠x) = ācāā * e(x)` for all `c` from `š` and `x` from `V`.
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