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Specification of Reactive Hardware/Software Systems - Electronic ...

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430 Pro<strong>of</strong>s <strong>of</strong> Propositions and Transformations<br />

the pro<strong>of</strong> ¨<br />

<strong>of</strong> Transformation 12.<br />

Pro<strong>of</strong> <strong>of</strong> Transformation 13<br />

It is easily shown that = £<br />

( Cc <br />

Er)¥ ¥ ¥¡ ¡ ¡ ¥ (E1 Sysp <br />

Sys § E1© ¥¡ ¡ ¥<br />

¡ ¥ © Pr ¥ §<br />

p BSpec P1 Er ,<br />

Sysp £<br />

Sys )¦ ¦ ¥ ( <br />

§ BSpece Cc ¥ envs¥ E1£ ¡ ¡ ¡£ Er¢ Sysp <br />

Sys ¥ Sys ¥<br />

)¦ ¥ ¥<br />

e p BSpec Sys is a weak bisimulation,<br />

so (i) and (ii) hold if ¢<br />

¡ is replaced by ¢<br />

. For the transformation<br />

equivalence part <strong>of</strong> (i), we observe that Reset ( Cc <br />

¥¡ ¡ ¡ ¥ (E1 Er) , , Sysp <br />

¥<br />

<br />

Sys<br />

¥¡ ¡ ¡ ¥ <br />

) =<br />

c C (E1 Er) , , Sysp Sys , . Further from context condition (13’), it follows<br />

that BSpecp ¡ ¡ ¥ Er© Pr ¡ § E1© § ¥¡ P1 B<strong>Specification</strong>s. Then, using Lemma 1, we have that<br />

Reset ( BSpecp <br />

¡ ¡ ¥ Er© Pr § E1© § ¥¡ P1 , , Sysp Sys , ) = BSpecp <br />

¡ ¡ ¥ Er© Pr § E1© § ¥¡ P1 , ,<br />

Sysp Sys ¥ . Then by (i) (where ¢<br />

¡ is replaced by ¢<br />

) the result follows. For (ii) we have<br />

that Reset( <br />

§ BSpece Cc ¥ envs¥ E1£ ¡ ¡ ¡£ Er¢ Sysp Sys ¥ ) = Cc <br />

Er)¥ ¥ ¥¡ ¡ ¡ ¥ (E1 Sysp Sys ¥ and that Reset<br />

( BSpece envs¥ ¥ Sysp Sys ¥ ) = BSpecp ¡ ¡ ¥ Er© Pr § E1© § ¥¡ P1 , <br />

, Sysp Sys<br />

¨<br />

, . The result then<br />

follows from (i).<br />

Pro<strong>of</strong> <strong>of</strong> Transformation 14<br />

The observation equivalence part <strong>of</strong> the pro<strong>of</strong> consists <strong>of</strong> £<br />

showing that<br />

= ( Cb 1 (E1<br />

<br />

¥ Er)§ f1 ¥ ¥ Sys ¥¡ ¡ ¡ p <br />

b<br />

<br />

C2 (E1 ¥¡ ¡ ¡ ¥ Er)§ f2 ¥ ¥ Sys ¥ Sys ¥<br />

p ¡ ) (1) (2)¦ ¦<br />

£<br />

¥ Sys and<br />

( <br />

S § p£ e<br />

1 Cb ¡ ¡£ Er¢ § f1 ¥ env¥ Sys<br />

1 E1£ ¡ p <br />

§ S ¥ Sys ¥ p£ e<br />

2 Cb ¡ ¡£ Er¢ § f2 ¥ env¥ Sys<br />

2 E1£ ¡ p ¡ (1)¥ ) (2) (3)¦ and is ¥ Sys a<br />

weak bisimulation. The pro<strong>of</strong> proceeds by rule induction. The transformation equivalence<br />

part directly follows from the ¨<br />

definition <strong>of</strong> Reset.<br />

Pro<strong>of</strong> <strong>of</strong> Transformation 15<br />

The pro<strong>of</strong> is similar to the pro<strong>of</strong> <strong>of</strong> Transformation 11. ¨<br />

Proposition 6<br />

A sound and complete pro<strong>of</strong> system for transformation equivalence does not exist. ¨<br />

Pro<strong>of</strong> <strong>of</strong> Proposition 6<br />

The incompleteness result is a direct consequence <strong>of</strong> Proposition 7. ¨<br />

Proposition 7<br />

There does not exist a sound pro<strong>of</strong> system for transformation equivalence that is complete with<br />

respect to all specifications that are transformation equivalent according to 6. ¨<br />

Pro<strong>of</strong> <strong>of</strong> Proposition 7<br />

Assume that is a sound pro<strong>of</strong> system for ¢<br />

that is complete with respect to ¡ all<br />

specifications that are transformation equivalent according to 6. We have to derive<br />

<br />

a<br />

contradiction. To this SSpecA(¡ end (A(¡ let ¢ B)§ c© a¥ c© b ¥<br />

p (TM))<br />

¥ Sys (TM)) Sys<br />

<br />

and<br />

(A(¡ (TM))§ c© a¥ c© b ¢ B§ c© a¥ c© b )¥<br />

p (TM))<br />

¥ Sys Sys be system SSpecB(¡ specifications,<br />

where (TM)) and B are ¡ processes. (TM) is an initialisation parameter <strong>of</strong> A denoting<br />

A(¡<br />

a (POOSL) string that represents an encoding <strong>of</strong> Turing Machine TM, see [LP81]. If the<br />

NoComChange(¡ transformation condition (TM)) is SSpecA(¡ satisfied, specification (TM))<br />

can be SSpecB((¡ transformed into (TM)) by 6:

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