Results about division in extended non-negative reals #
This file establishes basic properties related to the inversion and division operations on ℝ≥0∞
.
For instance, as a consequence of being a DivInvOneMonoid
, ℝ≥0∞
inherits a power operation
with integer exponent.
Main results #
A few order isomorphisms are worthy of mention:
OrderIso.invENNReal : ℝ≥0∞ ≃o ℝ≥0∞ᵒᵈ
: The mapx ↦ x⁻¹
as an order isomorphism to the dual.orderIsoIicOneBirational : ℝ≥0∞ ≃o Iic (1 : ℝ≥0∞)
: The birational order isomorphism betweenℝ≥0∞
and the unit intervalSet.Iic (1 : ℝ≥0∞)
given byx ↦ (x⁻¹ + 1)⁻¹
with inversex ↦ (x⁻¹ - 1)⁻¹
orderIsoIicCoe (a : ℝ≥0) : Iic (a : ℝ≥0∞) ≃o Iic a
: Order isomorphism between an initial interval inℝ≥0∞
and an initial interval inℝ≥0
given by the identity map.orderIsoUnitIntervalBirational : ℝ≥0∞ ≃o Icc (0 : ℝ) 1
: An order isomorphism between the extended nonnegative real numbers and the unit interval. This isorderIsoIicOneBirational
composed with the identity order isomorphism betweenIic (1 : ℝ≥0∞)
andIcc (0 : ℝ) 1
.
Alias of the reverse direction of ENNReal.inv_ne_top
.
The inverse map fun x ↦ x⁻¹
is an order isomorphism between ℝ≥0∞
and its OrderDual
Equations
- OrderIso.invENNReal = { toEquiv := Equiv.trans (Equiv.inv ENNReal) OrderDual.toDual, map_rel_iff' := ⋯ }
Instances For
Equations
An order isomorphism between the extended nonnegative real numbers and the unit interval.
Equations
- ENNReal.orderIsoUnitIntervalBirational = ENNReal.orderIsoIicOneBirational.trans ((ENNReal.orderIsoIicCoe 1).trans (NNReal.orderIsoIccZeroCoe 1).symm)
Instances For
Alias of ENNReal.iSup_zero
.
Very general version for distributivity of multiplication over an infimum.
See ENNReal.mul_iInf_of_ne
for the special case assuming a ≠ 0
and a ≠ ∞
, and
ENNReal.mul_iInf
for the special case assuming Nonempty ι
.
Very general version for distributivity of multiplication over an infimum.
See ENNReal.iInf_mul_of_ne
for the special case assuming a ≠ 0
and a ≠ ∞
, and
ENNReal.iInf_mul
for the special case assuming Nonempty ι
.
If a ≠ 0
and a ≠ ∞
, then right multiplication by a
maps infimum to infimum.
See ENNReal.mul_iInf'
for the general case, and ENNReal.iInf_mul
for another special case that
assumes Nonempty ι
but does not require a ≠ 0
, and ENNReal
.
If a ≠ 0
and a ≠ ∞
, then right multiplication by a
maps infimum to infimum.
See ENNReal.iInf_mul'
for the general case, and ENNReal.iInf_mul
for another special case that
assumes Nonempty ι
but does not require a ≠ 0
.
See ENNReal.mul_iInf'
for the general case, and ENNReal.mul_iInf_of_ne
for another special
case that assumes a ≠ 0
but does not require Nonempty ι
.
See ENNReal.iInf_mul'
for the general case, and ENNReal.iInf_mul_of_ne
for another special
case that assumes a ≠ 0
but does not require Nonempty ι
.
Very general version for distributivity of division over an infimum.
See ENNReal.iInf_div_of_ne
for the special case assuming a ≠ 0
and a ≠ ∞
, and
ENNReal.iInf_div
for the special case assuming Nonempty ι
.
If a ≠ 0
and a ≠ ∞
, then division by a
maps infimum to infimum.
See ENNReal.iInf_div'
for the general case, and ENNReal.iInf_div
for another special case that
assumes Nonempty ι
but does not require a ≠ ∞
.
See ENNReal.iInf_div'
for the general case, and ENNReal.iInf_div_of_ne
for another special
case that assumes a ≠ ∞
but does not require Nonempty ι
.
Alias of ENNReal.finsetSum_iSup_of_monotone
.