On Thu, Apr 14, 2011 at 1:08 AM, Lu Zhao <[email protected]> wrote:
> On 04/13/2011 05:54 PM, Michael Norrish wrote:
>> On 14/04/11 08:35, Lu Zhao wrote:
>>> when I use SIMP_CONV (std_ss++PRED_SET_ss) [] s1, I want to get
>>> something like:
>>
>>> {(0x1w,8); (0x1w,4)} = {(0x1w,x)}
>>
>>> where x is either 8 or 4, since I don't care about it.
>>
>> This is impossible.  The cardinality of the set on the left is 2, the 
>> cardinality of the set on the right is 1.  You could trivially derive a 
>> contradiction if the equation above was a theorem.
>
> I used the above example, since I tried this:
>
> val s1 = mk_insert(e1, mk_insert(e1,``{}:(word32#num) set``))
>
> and "SIMP_CONV (std_ss++PRED_SET_ss) [] s1" gives:
>
>  > val it =  [] |- {(0x1w,4); (0x1w,4)} = {(0x1w,4)}: thm
>
> and I guessed there was something that could be done. I don't know that
> this is the cardinality issue. What I really need is an expression like
>
> !e. e IN s1 ==> something
>
> which only cares about the first element of e.

You can certainly write !e. e IN s1 ==> P (FST e1), for some predicate P...
You could also try IMAGE FST s1, to turn a set of pairs into a set of
first elements only.

>
> Since it's impossible, using a mapping seems to be the only solution now.
>
> Thanks a lot.
> Lu
>
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Benefiting from Server Virtualization: Beyond Initial Workload 
Consolidation -- Increasing the use of server virtualization is a top
priority.Virtualization can reduce costs, simplify management, and improve 
application availability and disaster protection. Learn more about boosting 
the value of server virtualization. http://p.sf.net/sfu/vmware-sfdev2dev
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