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(*  Title:      HOL/IMPP/Natural.thy
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    ID:         $Id$
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    Author:     David von Oheimb (based on a theory by Tobias Nipkow et al), TUM
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    Copyright   1999 TUM
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Natural semantics of commands
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*)
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Natural = Com + 
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(** Execution of commands **)
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consts	 evalc :: "(com * state *       state) set"
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       "@evalc":: [com,state,    state] => bool	("<_,_>/ -c-> _" [0,0,  51] 51)
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	 evaln :: "(com * state * nat * state) set"
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       "@evaln":: [com,state,nat,state] => bool	("<_,_>/ -_-> _" [0,0,0,51] 51)
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translations  "<c,s> -c-> s'" == "(c,s,  s') : evalc"
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              "<c,s> -n-> s'" == "(c,s,n,s') : evaln"
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consts
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  newlocs :: locals
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  setlocs :: state => locals => state
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  getlocs :: state => locals
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  update  :: state => vname => val => state	("_/[_/::=/_]" [900,0,0] 900)
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syntax (* IN Natural.thy *)
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  loc :: state => locals    ("_<_>" [75,0] 75)
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translations
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  "s<X>" == "getlocs s X"
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inductive evalc
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  intrs
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    Skip    "<SKIP,s> -c-> s"
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    Assign  "<X :== a,s> -c-> s[X::=a s]"
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    Local   "<c, s0[Loc Y::= a s0]> -c-> s1 ==>
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             <LOCAL Y := a IN c, s0> -c-> s1[Loc Y::=s0<Y>]"
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    Semi    "[| <c0,s0> -c-> s1; <c1,s1> -c-> s2 |] ==>
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             <c0;; c1, s0> -c-> s2"
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    IfTrue  "[| b s; <c0,s> -c-> s1 |] ==>
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             <IF b THEN c0 ELSE c1, s> -c-> s1"
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    IfFalse "[| ~b s; <c1,s> -c-> s1 |] ==>
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             <IF b THEN c0 ELSE c1, s> -c-> s1"
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    WhileFalse "~b s ==> <WHILE b DO c,s> -c-> s"
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    WhileTrue  "[| b s0;  <c,s0> -c-> s1;  <WHILE b DO c, s1> -c-> s2 |] ==>
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                <WHILE b DO c, s0> -c-> s2"
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    Body       "<the (body pn), s0> -c-> s1 ==>
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                <BODY pn, s0> -c-> s1"
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    Call       "<BODY pn, (setlocs s0 newlocs)[Loc Arg::=a s0]> -c-> s1 ==>
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                <X:=CALL pn(a), s0> -c-> (setlocs s1 (getlocs s0))
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                                         [X::=s1<Res>]"
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inductive evaln
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  intrs
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    Skip    "<SKIP,s> -n-> s"
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    Assign  "<X :== a,s> -n-> s[X::=a s]"
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    Local   "<c, s0[Loc Y::= a s0]> -n-> s1 ==>
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             <LOCAL Y := a IN c, s0> -n-> s1[Loc Y::=s0<Y>]"
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    Semi    "[| <c0,s0> -n-> s1; <c1,s1> -n-> s2 |] ==>
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             <c0;; c1, s0> -n-> s2"
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    IfTrue  "[| b s; <c0,s> -n-> s1 |] ==>
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             <IF b THEN c0 ELSE c1, s> -n-> s1"
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    IfFalse "[| ~b s; <c1,s> -n-> s1 |] ==>
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             <IF b THEN c0 ELSE c1, s> -n-> s1"
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    WhileFalse "~b s ==> <WHILE b DO c,s> -n-> s"
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    WhileTrue  "[| b s0;  <c,s0> -n-> s1;  <WHILE b DO c, s1> -n-> s2 |] ==>
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                <WHILE b DO c, s0> -n-> s2"
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    Body       "<the (body pn), s0> -    n-> s1 ==>
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                <BODY pn, s0> -Suc n-> s1"
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    Call       "<BODY pn, (setlocs s0 newlocs)[Loc Arg::=a s0]> -n-> s1 ==>
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                <X:=CALL pn(a), s0> -n-> (setlocs s1 (getlocs s0))
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                                         [X::=s1<Res>]"
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end
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