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import Mathlib
import OAI.SetTheory.PartitionConsistency.Algebra.ProbePresentations
namespace OAI
/-! ## Persistence of the full probe profile at successor stages -/
namespace PartitionConsistency.DiagramOrder
universe u v
/-- The full profile of a probe, with downsets taken in the entire monoid
rather than only in the base over which the probe was adjoined. -/
structure ProbeProfile {M : Type u} [Monoid M]
(a b e m : M) (n : ℕ → M) : Prop where
exit : m * b = a * e
not_divides : ¬ m ∣ a
divisors : ∀ x : M, x ∣ a ∧ x ∣ m ↔ ∃ i : ℕ, x ∣ n i
joins : ∀ x : M, x ∣ a → ¬ x ∣ m →
∀ z : M, x ∣ z ∧ m ∣ z ↔ a * e ∣ z
/-- An old gate controls both old right multiples and intersections with
old cones not containing the new element. In probe normal forms this is
exactly the first-letter exit rule. -/
structure OldGate {M : Type u} {N : Type v} [Monoid M] [Monoid N]
(f : M →* N) (w : N) (g : M) : Prop where
divides : w ∣ f g
old_multiples : ∀ x : M, w ∣ f x ↔ g ∣ x
intersections : ∀ x : M, ¬ f x ∣ w →
∀ z : N, w ∣ z ∧ f x ∣ z ↔ f g ∣ z ∧ f x ∣ z
/-- Only elements with an old right multiple need a gate. For mergers
all such elements are already old, so the second alternative is unused. -/
def HasOldGates {M : Type u} {N : Type v} [Monoid M] [Monoid N]
(f : M →* N) : Prop :=
∀ w : N, (∃ a : M, w ∣ f a) →
(∃ x : M, f x = w) ∨ ∃ g : M, OldGate f w g
namespace ProbeProfile
variable {M : Type u} {N : Type v} [Monoid M] [Monoid N]
{a b e m : M} {n : ℕ → M} (h : ProbeProfile a b e m n)
{f : M →* N} (hf : Conservative f) (hg : HasOldGates f)
include hf hg h
/-- Source `lem:mono-profile-persistence`, successor step. The new
full downward closure of the original path, not its old set of divisors,
is the profile in the extension. -/
theorem map : ProbeProfile (f a) (f b) (f e) (f m) (f ∘ n) where
exit := by rw [← f.map_mul, h.exit, f.map_mul]
not_divides hm := h.not_divides ((hf.dvd_iff m a).1 hm)
divisors x := by
constructor
· rintro ⟨hxa,hxm⟩
rcases hg x ⟨a,hxa⟩ with ⟨y,rfl⟩ | ⟨g,hg⟩
· obtain ⟨i,hi⟩ := (h.divisors y).1 ⟨(hf.dvd_iff y a).1 hxa,
(hf.dvd_iff y m).1 hxm⟩
exact ⟨i,f.map_dvd hi⟩
· obtain ⟨i,hi⟩ := (h.divisors g).1 ⟨(hg.old_multiples a).1 hxa,
(hg.old_multiples m).1 hxm⟩
exact ⟨i,hg.divides.trans (f.map_dvd hi)⟩
· rintro ⟨i,hi⟩
have hni := (h.divisors (n i)).2 ⟨i,dvd_refl _⟩
exact ⟨hi.trans (f.map_dvd hni.1),hi.trans (f.map_dvd hni.2)⟩
joins x hxa hxm z := by
rcases hg x ⟨a,hxa⟩ with ⟨y,rfl⟩ | ⟨g,hg⟩
· simpa only [f.map_mul] using hf.intersections y m (a * e)
(h.joins y ((hf.dvd_iff y a).1 hxa) (fun hy => hxm (f.map_dvd hy))) z
· have hga := (hg.old_multiples a).1 hxa
have hgm : ¬ g ∣ m := fun hgm => hxm ((hg.old_multiples m).2 hgm)
have hmx : ¬ f m ∣ x := fun hmx => h.not_divides ((hf.dvd_iff m a).1 (hmx.trans hxa))
rw [hg.intersections m hmx z]
simpa only [f.map_mul] using hf.intersections g m (a * e) (h.joins g hga hgm) z
end ProbeProfile
end PartitionConsistency.DiagramOrder
namespace PartitionConsistency.ProbeAlgebra.Path
universe u
open DiagramOrder
variable {M : Type u} [LeftCancelMonoid M] [IsConical M] {a e : M}
(P : Path M a) (he : e ≠ 1) (b : M)
/-- The gate hypothesis of profile persistence is supplied by the actual
probe extension, including all new words, not just the adjoined generators. -/
theorem hasOldGates (hM : HasConditionalJoins (LeftDivOrder M)) :
HasOldGates (Word.oldHom (P.alphabet he) b) := by
intro w hw
classical
by_cases ho : ∃ x : M, Word.old (P.alphabet he) b x = w
· exact Or.inl ho
· obtain ⟨y,hy⟩ := hw
cases hs : Word.head (P.alphabet he) b w with
| none => exact (ho (by
obtain ⟨x,hx⟩ := (Word.head_eq_none_iff _ _ w).1 hs
exact ⟨x,hx.symm⟩)).elim
| some s =>
obtain ⟨g,hg⟩ := Word.exists_gate_of_exit (P.alphabet he) b (P.oldIntersections he b hM)
w hs hy (by intro h; cases h)
refine Or.inr ⟨g,Word.Gate.dvd _ _ hg,Word.Gate.dvd_old_iff _ _ hg,?_⟩
intro x hx z
change (w ∣ z ∧ Word.old (P.alphabet he) b x ∣ z) ↔
Word.old (P.alphabet he) b g ∣ z ∧ Word.old (P.alphabet he) b x ∣ z
simpa only [and_comm] using Word.Gate.old_intersection _ _ hg hs
(fun hd => hx ((Word.old_dvd_iff_headDiv _ _ x w).2 hd)) z
/-- The profile initially holds with all downsets in the new monoid. -/
theorem probeProfile (hM : HasConditionalJoins (LeftDivOrder M)) (hb : b ≠ 1) :
ProbeProfile (Word.old (P.alphabet he) b a) (Word.old (P.alphabet he) b b)
(Word.old (P.alphabet he) b e) (P.probe he b hb 0)
(fun i => Word.old (P.alphabet he) b (P.node i)) where
exit := P.probe_zero_mul_b he b hb
not_divides := P.probe_not_dvd_a he b hb
divisors x := by simpa only [and_comm] using P.probe_full_profile he b hb hM x
joins x hxa hxm z := P.probe_join_profile he b hb hM hxa hxm z
/-- The same profile survives a later probe operation, whose parameters
need have no relation to the parameters of the original probe. -/
theorem preserve_profile (hM : HasConditionalJoins (LeftDivOrder M))
{a₀ b₀ e₀ m₀ : M} {n₀ : ℕ → M} (h : ProbeProfile a₀ b₀ e₀ m₀ n₀) :
ProbeProfile (Word.old (P.alphabet he) b a₀) (Word.old (P.alphabet he) b b₀)
(Word.old (P.alphabet he) b e₀) (Word.old (P.alphabet he) b m₀)
(fun i => Word.old (P.alphabet he) b (n₀ i)) :=
h.map (P.oldHom_conservative he b) (P.hasOldGates he b hM)
end PartitionConsistency.ProbeAlgebra.Path
namespace PartitionConsistency.MergerAlgebra.Word
universe u v
open DiagramOrder
variable {M : Type u} {D : Type v} [Monoid M] [RightFreeAction M D]
/-- A merger introduces no new divisor of any old element. -/
theorem hasOldGates : HasOldGates (oldHom : M →* Word M D) := by
rintro w ⟨a,q,hq⟩
obtain ⟨x,y,hx,hy,hxy⟩ := factors_of_old hq.symm
exact Or.inl ⟨x,hx.symm⟩
/-- Source profile persistence for a merger successor. -/
theorem preserve_profile {a b e m : M} {n : ℕ → M} (h : ProbeProfile a b e m n) :
ProbeProfile (old a : Word M D) (old b) (old e) (old m) (fun i => old (n i)) :=
h.map oldHom_conservative hasOldGates
end PartitionConsistency.MergerAlgebra.Word
end OAI