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(A can be mapped 1-1 into a proper subpart of itself)

Dedekind's formulation of infinite class

Who Cites Dedekind infinite?
Dedekind_infiniteDef  Dedekind-Infinite(A) == a:A, f:(AA). Inj(A; A; f) & (x:A. f(x) = a)
Thm*  A:Type. Dedekind-Infinite(A)  Prop
notDef  A == A  False
Thm*  A:Prop. (A)  Prop
injectDef  Inj(A; B; f) == a1,a2:A. f(a1) = f(a2)  B  a1 = a2
Thm*  A,B:Type, f:(AB). Inj(A; B; f)  Prop

Syntax:Dedekind-Infinite(A) has structure: Dedekind_infinite(A)

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WhoCites Definitions DiscreteMath Sections DiscrMathExt Doc