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In partition calculus, part of combinatorial set theory, which is a branch of mathematics, the Erdős–Rado theorem is a basic result, extending Ramsey's theorem to uncountable sets. ==Statement of the theorem== If ''r'' ≥ 0 is finite, ''κ'' is an infinite cardinal, then : where exp0(κ) = ''κ'' and inductively exp''r''+1(κ)=2exp''r''(κ). This is sharp in the sense that exp''r''(κ)+ cannot be replaced by exp''r''(κ) on the left hand side. The above partition symbol describes the following statement. If ''f'' is a coloring of the ''r+1''-element subsets of a set of cardinality exp''r''(κ)+, in ''κ'' many colors, then there is a homogeneous set of cardinality ''κ+'' (a set, all whose ''r+1''-element subsets get the same ''f''-value). 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Erdős–Rado theorem」の詳細全文を読む スポンサード リンク
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