def
definition
IdentityOn
show as:
view math explainer →
open explainer
Generate a durable explainer page for this declaration.
open lean source
IndisputableMonolith.Foundation.DomainBootstrap on GitHub at line 65.
browse module
All declarations in this module, on Recognition.
explainer page
depends on
used by
formal source
62variable {K : Type*}
63
64/-- Identity, generic field version. -/
65def IdentityOn [Zero K] [LT K] (C : ComparisonOperatorOn K) : Prop :=
66 ∀ x : K, 0 < x → C x x = 0
67
68/-- Non-contradiction, generic field version. -/
69def NonContradictionOn [LT K] [Zero K] (C : ComparisonOperatorOn K) : Prop :=
70 ∀ x y : K, 0 < x → 0 < y → C x y = C y x
71
72/-- Scale invariance, generic field version. -/
73def ScaleInvariantOn [Zero K] [LT K] [Mul K] (C : ComparisonOperatorOn K) : Prop :=
74 ∀ x y lam : K, 0 < x → 0 < y → 0 < lam →
75 C (lam * x) (lam * y) = C x y
76
77/-- Distinguishability, generic field version. -/
78def DistinguishabilityOn [Zero K] [LT K] (C : ComparisonOperatorOn K) : Prop :=
79 ∃ x y : K, 0 < x ∧ 0 < y ∧ C x y ≠ 0
80
81/-! ## 2. The bootstrap theorem
82
83The Law of Logic on an ambient field `K` plus Archimedean +
84Dedekind-completeness implies `K ≃+*o ℝ`. The proof is by reduction
85to Mathlib's classical characterization of `ℝ`.
86
87The completeness hypothesis is the standard analytic input that makes
88"continuous comparison" non-vacuous; without it, the comparison
89operator could live on `ℚ` or any incomplete subfield. With it, `K`
90is forced to be `ℝ`.
91-/
92
93/-- A linearly ordered field is **Logic-supported** when a comparison
94operator on it satisfies the four Aristotelian conditions plus scale
95invariance and distinguishability. We package the ordered-field