text: 鑽石原則意味著存在。定義.已隱藏部分未翻譯內容，歡迎參與[ 翻譯]。The diamond principle "A" ∩ "α""Aα" is stationary in "ω"1.There are several equivalent forms of the diamond principle. One states that there is a countable collection "A" ∩ "α""A""α".More generally, for a given cardinal number ⟨"Aα" : "α" ∈ "S"⟩ such that"Aα"} is stationary in "κ"The principle ◊.The diamond-plus principle "C" ∩ "α" ∈ A"α".屬性和使用.The diamond principle ◊ principle and the existence of a Kurepa tree.For all cardinals 2"κ""κ"+ for stationary "κ".Shelah showed that the diamond principle solves the Whitehead problem by implying that every Whitehead group is free.
metadata.dataset: erhwenkuo/wikipedia-zhtw
metadata.title: 鑽石原則
metadata.url: https://zh.wikipedia.org/wiki?curid=8075537