Maps between real and extended non-negative real numbers #
This file focuses on the functions ENNReal.toReal : ℝ≥0∞ → ℝ and ENNReal.ofReal : ℝ → ℝ≥0∞ which
were defined in Data.ENNReal.Basic. It collects all the basic results of the interactions between
these functions and the algebraic and lattice operations, although a few may appear in earlier
files.
This file provides a positivity extension for ENNReal.ofReal.
Main theorems #
trichotomy (p : ℝ≥0∞) : p = 0 ∨ p = ∞ ∨ 0 < p.toReal: often used forWithLpandlpdichotomy (p : ℝ≥0∞) [Fact (1 ≤ p)] : p = ∞ ∨ 1 ≤ p.toReal: often used forWithLpandlptoNNReal_iInfthroughtoReal_sSup: these declarations allow for easy conversions between indexed or set infima and suprema inℝ,ℝ≥0andℝ≥0∞. This is especially useful becauseℝ≥0∞is a complete lattice.
If a ≤ b + c and a = ∞ whenever b = ∞ or c = ∞, then
ENNReal.toReal a ≤ ENNReal.toReal b + ENNReal.toReal c. This lemma is useful to transfer
triangle-like inequalities from ENNReals to Reals.
If a ≤ b + c, b ≠ ∞, and c ≠ ∞, then
ENNReal.toReal a ≤ ENNReal.toReal b + ENNReal.toReal c. This lemma is useful to transfer
triangle-like inequalities from ENNReals to Reals.
Alias of the reverse direction of ENNReal.ofReal_eq_zero.
Alias of ENNReal.ofReal_lt_natCast.
Alias of ENNReal.natCast_le_ofReal.
Alias of ENNReal.ofReal_le_natCast.
Alias of ENNReal.natCast_lt_ofReal.
Alias of ENNReal.ofReal_eq_natCast.
ENNReal.toNNReal as a MonoidHom.
Equations
- ENNReal.toNNRealHom = { toFun := ENNReal.toNNReal, map_one' := ENNReal.toNNRealHom.proof_1, map_mul' := ⋯ }
Instances For
If x ≠ ∞, then right multiplication by x maps infimum over a nonempty type to infimum. See
also ENNReal.iInf_mul_of_ne that assumes x ≠ 0 but does not require [Nonempty ι].
If x ≠ ∞, then left multiplication by x maps infimum over a nonempty type to infimum. See
also ENNReal.mul_iInf_of_ne that assumes x ≠ 0 but does not require [Nonempty ι].
supr_mul, mul_supr and variants are in Topology.Instances.ENNReal.
Alias of ENNReal.iSup_natCast.
Extension for the positivity tactic: ENNReal.ofReal.