Results on TrivSqZeroExt R M related to the norm #
This file contains results about NormedSpace.exp for TrivSqZeroExt.
It also contains a definition of the $ℓ^1$ norm,
which defines $\|r + m\| \coloneqq \|r\| + \|m\|$.
This is not a particularly canonical choice of definition,
but it is sufficient to provide a NormedAlgebra instance,
and thus enables NormedSpace.exp_add_of_commute to be used on TrivSqZeroExt.
If the non-canonicity becomes problematic in future,
we could keep the collection of instances behind an open scoped.
Main results #
TrivSqZeroExt.fst_expTrivSqZeroExt.snd_expTrivSqZeroExt.exp_inlTrivSqZeroExt.exp_inr- The $ℓ^1$ norm on
TrivSqZeroExt:TrivSqZeroExt.instL1SeminormedAddCommGroupTrivSqZeroExt.instL1SeminormedRingTrivSqZeroExt.instL1SeminormedCommRingTrivSqZeroExt.instL1IsBoundedSMulTrivSqZeroExt.instL1NormedAddCommGroupTrivSqZeroExt.instL1NormedRingTrivSqZeroExt.instL1NormedCommRingTrivSqZeroExt.instL1NormedSpaceTrivSqZeroExt.instL1NormedAlgebra
TODO #
- Generalize more of these results to non-commutative
R. In principle, under sufficient conditions we should expect(exp x).snd = ∫ t in 0..1, exp (t • x.fst) • op (exp ((1 - t) • x.fst)) • x.snd(Physics.SE, and https://link.springer.com/chapter/10.1007/978-3-540-44953-9_2).
If NormedSpace.exp R x.fst converges to e
then (NormedSpace.exp R x).snd converges to e • x.snd.
If NormedSpace.exp R x.fst converges to e
then NormedSpace.exp R x converges to inl e + inr (e • x.snd).
Polar form of trivial-square-zero extension.
More convenient version of TrivSqZeroExt.eq_smul_exp_of_invertible for when R is a
field.
The $ℓ^1$ norm on the trivial square zero extension #
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- TrivSqZeroExt.instL1NormedAlgebra 𝕜 = { toAlgebra := TrivSqZeroExt.algebra' 𝕜 R M, norm_smul_le := ⋯ }