2013-08-18 19:48:02 +00:00
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Definition xor (x y : Bool) : Bool := (not x) = y
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2013-08-20 00:25:15 +00:00
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Infixr 50 ⊕ : xor
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2013-08-18 19:48:02 +00:00
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Show xor true false
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Eval xor true true
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Eval xor true false
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Variable a : Bool
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Show a ⊕ a ⊕ a
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Check Subst
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Theorem EM2 (a : Bool) : a \/ (not a) :=
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Case (fun x : Bool, x \/ (not x)) Trivial Trivial a
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Check EM2
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Check EM2 a
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