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Counting connected contours

5 fully proved

A. Failure of the origin bound

DefinitionTwo-site set \(\{0, p\}\)#✓fully proved

The two-site set {0, p}.

noncomputable def pcc_pairCluster (p : Site d) : Finset (Site d) := {origin d, p}
Uses 2

B. Connected clusters

DefinitionNearest-neighbour graph restricted to a set#✓fully proved

The nearest-neighbour graph restricted to K.

noncomputable def latticeOn (K : Set (Site d)) : SimpleGraph (Site d) where
  Adj x y := (hypercubicLattice d).Adj x y ∧ x ∈ K ∧ y ∈ K
  symm := ⟨fun _ _ ⟨h1, h2, h3⟩ => ⟨h1.symm, h3, h2⟩⟩
  loopless := ⟨fun _ h => (hypercubicLattice d).irrefl h.1⟩
Uses 2 · Used by 7

DefinitionConnected cluster through the origin in the nearest-neighbour graph#✓fully proved

K is connected in the nearest-neighbour graph.

def IsConnectedCluster (K : Finset (Site d)) : Prop :=
  origin d ∈ K ∧ ∀ x ∈ K, (latticeOn (↑K : Set (Site d))).Reachable (origin d) x
Uses 3 · Used by 8

DefinitionConnected clusters in the box containing the origin#✓fully proved

The connected finite sets of sites in Λ_n containing the origin.

noncomputable def connClusterFamily (n : ℕ) : Finset (Finset (Site d)) :=
  (clusterFamily (d := d) n).filter (fun K => IsConnectedCluster K)
Uses 3 · Used by 8

DefinitionPeierls series bound on the connected-cluster contour sum#✓fully proved

The sum of e^{-2β |∂K|} over connected clusters is at most the Peierls series.

def ConnectedContourCountBound (d n : ℕ) (β : ℝ) : Prop :=
  ∑ K ∈ connClusterFamily (d := d) n,
      Real.exp (-(2 * β) * (contourLen (↑K) (bondFinsetTouch d n) : ℝ))
    ≤ peierlsBound d β
Uses 5

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