Re: Priorities in SPoC

[A E Lawrence <adrian.lawrence@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>]

The first program Dennis posted is actually a bit awkward.

Denis A Nicole wrote:

[snip]
> PRI ALT
>   SKIP
>     P    ==     P
>   SKIP
>     Q
After puzzling about how to translate that into CSPP, I tried the
ordinary

ALT
  SKIP
    P
  SKIP
    Q

As far as I can see the occam{2,3} Reference manuals simply don't
specify what this means So I consulted the Michael,Bill & Brian
"Denotational Semantics for occam2". And they confirm there that SKIP
guards are really very different
from ordinary input guards. 

I am out of time, but I think that CSPP has nothing to say about the
meaning
of Skip guards. Rather we must tell it. We have a precise definition
according to Michael at al's paper for the ordinary case. When I have
understood what all those semantic functions are, it should be easy to
extend it to the PRI cases.
Of course, we all expect (will insist?) that the programs above are P
and
P |~| Q  .

In haste.

Adrian
--
Dr A E Lawrence (from home)