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Cofinite Filter of $B$ centered at $A$ (Definition II.4.3)

  • Cofinite Filter of $B$ centered at $A$ (Definition II.4.3) #Card
    • For $A \subset B \subset X$, the filter: $$(B, A)_0 := {F \subset X : A \subset F, \operatorname{card}(B \setminus F) < \infty}$$ It decomposes as $(B, A)_0 = (B \setminus A)_0 \wedge {A}^\uparrow$.

Back

Section titled “Back”

For $A \subset B \subset X$, the filter: $$(B, A)_0 := {F \subset X : A \subset F, \operatorname{card}(B \setminus F) < \infty}$$ It decomposes as $(B, A)_0 = (B \setminus A)_0 \wedge {A}^\uparrow$.

Lean

Section titled “Lean”

本書独自構成。Lean に直接対応なし