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declared open · formalizederdos:130
For an infinite planar set in strong general position, how large can the chromatic and clique numbers of its positive-integer-distance graph be - in particular, can the chromatic number be infinite? Yes: there is such a set, no three collinear and no four concyclic, with infinite chromatic number.
graph theorychromatic numberN/A4 sources
declared open · formalized · $500erdos:593
Which finite triple systems occur in every triple system of uncountable chromatic number? The claimed characterization: exactly those that, after removing isolated vertices, are linear, have every hyperedge-node of their Levi graph meeting a bridge, and have every Berge cycle even.
set theorygraph theoryhypergraphsN/A4 sources
declared proved (Lean) · formalizederdos:750
True ↔ ∀ (f : ℕ → NNReal), Filter.Tendsto f Filter.atTop Filter.atTop → ∃ V G, G.chromaticNumber = ⊤ ∧ ∀ (m : ℕ) (S : Set V), 0 < m → S.ncard = m → ∃ I ⊆ S, G.IsIndepSet I ∧ ↑m / 2 - f m ≤ ↑I.ncard
graph theorychromatic numberN/A5 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 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 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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