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(* Title: FOCUS/ex/Coind.thy
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ID: $ $
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Author: Franz Regensburger
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Copyright 1993 195 Technische Universitaet Muenchen
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Example for co-induction on streams
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*)
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Coind = Stream + Dnat +
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consts
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nats :: "dnat stream"
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from :: "dnat è dnat stream"
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defs
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nats_def "nats Ú fix`(¤h.dzero&&(smap`dsucc`h))"
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from_def "from Ú fix`(¤h n.n&&(h`(dsucc`n)))"
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end
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(*
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smap`f`Ø = Ø
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xÛØ çè smap`f`(x&&xs) = (f`x)&&(smap`f`xs)
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nats = dzero&&(smap`dsucc`nats)
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from`n = n&&(from`(dsucc`n))
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*)
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