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Narrowed tochromatic number ×Clear all

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61 problems · 2/2NumberSourcesGraph view
declared proved (Lean) · formalizederdos:923
True ↔ ∀ (V : Type u_1) (n : ℕ), ∃ k, ∀ (G : SimpleGraph V), ↑k ≤ G.chromaticNumber → ∃ H ≤ G, ↑n ≤ H.chromaticNumber ∧ H.CliqueFree 3
graph theorychromatic numberN/A5 sources
declared open · formalizederdos:944
True ↔ ∀ k ≥ 4, ∀ r ≥ 1, ∃ V G, Erdos944.SimpleGraph.IsErdos944 G k r
graph theorychromatic numberN/A2 sources
declared openerdos:1032
Do arbitrarily large 4-chromatic edge-critical graphs exist with minimum degree bounded below by a positive constant times the number of vertices?
graph theorychromatic numberpossible3 sources
declared open · formalizederdos:1068
True ↔ ∀ (V : Type) (G : SimpleGraph V), G.chromaticCardinal = Cardinal.aleph 1 → ∃ s, s.Countable ∧ (SimpleGraph.induce s G).InfinitelyConnected
graph theoryset theorychromatic numberN/A2 sources
declared solvederdos:1091
Erdős problem 1091
geometrychromatic numberN/A3 sources
declared disproved · formalizederdos:1092
False ↔ (fun n => ↑n) =o[Filter.atTop] fun n => ↑(Erdos1092.f 2 n)
geometrychromatic numberN/A5 sources
declared open · formalizederdos:1104
∃ c₁, 0 < c₁ ∧ c₁ ≤ 1 ∧ ∀ᶠ (n : ℕ) in Filter.atTop, c₁ * √↑n / √(Real.log ↑n) ≤ ↑(Erdos1104.triangleFreeMaxChromatic n)
graph theorychromatic numberA2925282 sources
declared openerdos:1156
Erdős problem 1156
graph theorychromatic numberN/A
declared open · formalizederdos:1175
True ↔ ∀ (κ : Cardinal.{u_1}), Cardinal.aleph0 < κ → ∃ μ, ∀ (V : Type u_1) (G : SimpleGraph V), G.chromaticCardinal = μ → ∃ H, H.coe.CliqueFree 3 ∧ H.coe.chromaticCardinal = κ
set theorychromatic numberN/A2 sources
declared not disprovable · formalizederdos:1176
True ↔ ∀ {V : Type u_1} (G : SimpleGraph V), G.chromaticCardinal = Cardinal.aleph 1 → ∃ EColor, ∃ (_ : Cardinal.mk EColor = Cardinal.aleph 1), ∃ c_edge, ∀ (VColor : Type), Cardinal.mk VColor ≤ Cardinal.aleph 0 → ∀ (c_vert : V → VColor), ∃ vc, ∀ (ec : EColor), ∃ u v, ∃ (h : G.Adj u v), c_vert u = vc ∧ c_vert v = vc ∧ c_edge ⟨s(u, v), h⟩ = ec
set theorychromatic numberN/A2 sources
declared openerdos:1177
For a finite forbidden triple system GG, what exact uncountable chromatic cardinalities occur among GG-free triple systems, and how do those spectra interact? The revised manuscript answers the three exact-cardinal questions and claims a complete spectrum dichotomy.
set theorychromatic numberhypergraphsN/A3 sources

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