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(* Title: HOL/Hoare/ExamplesAbort.thy
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Author: Tobias Nipkow
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Copyright 1998 TUM
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*)
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72990
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section \<open>Some small examples for programs that may abort\<close>
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theory ExamplesAbort
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imports Hoare_Logic_Abort
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begin
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lemma "VARS x y z::nat
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{y = z & z \<noteq> 0} z \<noteq> 0 \<rightarrow> x := y div z {x = 1}"
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by vcg_simp
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lemma
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"VARS a i j
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{k <= length a & i < k & j < k} j < length a \<rightarrow> a[i] := a!j {True}"
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by vcg_simp
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lemma "VARS (a::int list) i
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{True}
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i := 0;
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WHILE i < length a
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INV {i <= length a}
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DO a[i] := 7; i := i+1 OD
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{True}"
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by vcg_simp
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end
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