OAI/Geometry/HyperbolicGroups/ConnectedLevels.lean

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3 declarations, 0 contain sorry, 0 declared as axioms

  1. lemma OAI.HyperbolicObstruction.PlanarRecursion.preconnected_color_constant line 14
  2. theorem OAI.HyperbolicObstruction.PlanarRecursion.connected_avoids_level line 31

    Source documentation

    A connected set avoiding an integer level cannot pass from below to above it when adjacent depths differ by at most one. Isolated/empty induced graphs are covered by Preconnected, with no global connectedness or positivity assumption.

    theorem connected_avoids_level (G : SimpleGraph V) (depth : V → ℤ)
        (hd : ∀ v w, G.Adj v w → depth v ≤ depth w+1 ∧ depth w ≤ depth v+1)
        (U : Set V) (hc : (G.induce U).Preconnected) (z : ℤ)
        (hz : ∀ v ∈ U, depth v ≠ z) :
        ∀ v ∈ U, ∀ w ∈ U, (depth v < z ↔ depth w < z) := by
    …
  3. lemma OAI.HyperbolicObstruction.PlanarRecursion.graph_dist_int_adj line 46