天天热点！ZFC9A
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2023-05-28 15:37:09
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(∀x)(∀y)(∀z)(x=y↔(z∈x↔z∈y))(∃x)(∀y)(y∉x)(∀x)(∀y)(∃z)(∀u)(u∈z↔((u=x)∨(u=y)))(∀x)(∃y)(∀z)(∃u)(z∈y↔(z∈u∧u∈x))(∀x)(∃y)(∀z)(z∈y↔(z∈x∧P(z)))
(∀x)(∃y)(∀z)(z∈y ↔ (∀u)(u∈z ∧ u∈x))(∀x)(x≠∅ → (∃y)(y∈x ∧ x∩y=∅))(∃x)(∅∈x ∧ (∀y)(y∈x → (y∪{y}∈x)))(∀x)(∃!y)P(x,y) → (∀t)(∃s)(∀u)(u∈s ↔ (∃z)(z∈t ∧ P(x,u)))
源文件链接：
https://gitee.com/wu-org/go/blob/research/foo/SetTheory/somethinguseful.md
