itaps-parallel Proposal for handling queries with parts, sets, and partitions

[Tim Tautges]

But the language and constructs used to answer the questions (and to ask 
the questions) is what we call the data model.  For example, the data 
model says we pass references to entities back and forth using handles. 
  As proposed by you, the data model for parts refers to them using 
integer ids.  I think those ids could just as easily be handles, and 
your implementation could implement those handles as integers.

As for how those are actually represented underneath, I strongly agree 
we shouldn't force implementations to use one thing or another.  I'm 
just saying the handles used to refer to parts and partitions should 
also be usable in the other functions that deal with sets.  I wasn't 
very careful in making this distinction in my writeup I sent earlier.

So, to go back to my original question, and back to what we had agreed 
going out of the last bootcamp: why can't we pass part/partition handles 
into existing functions in place of set handles, and have them 
interpreted specially if they happen to be part/partition handles? 
Mark, that wouldn't force you to actually represent parts/partitions as 
sets; you could interpret set handles in a specific range as 
part/partition ids.

This would make the question of efficient booleans on the results 
completely separable from the parallel interface discussion, as well as 
allowing us to use our current function set dealing with entity sets to 
also apply to parts/partitions.

- tim

Mark Shephard wrote:
> Tim,
> 
> No that is not true!!! The questions asked by an interface do not 
> require specific information be stored. It requires the ability to 
> answer the question!!!!! We very much use a partition model without sets 
> or explicit storage of reverse classification. Reasons for this are 
> explained in various papers. However, knowing that is less the issue. 
> The reason for interface API is to allow people to answer the questions, 
> not force them to use specific structures.
> 
> Mark
> 
> Tim Tautges wrote:
>> Then why do we need functions operating on parts or partitions at all? 
>> Those are reverse classification-type queries, right?
>>
>> - tim
>>
>> Mark Shephard wrote:
>>>
>>>
>>> Since the first thing that was agreed to is that there would be the 
>>> ability to deal parts that does not require an implementation to do 
>>> things via sets (reverse classification), I sure hope we are not 
>>> getting this issue confused again. As discussed in some technical 
>>> detail at the boot camp, there are two high level approaches one 
>>> based on classification (no use of sets) and reverse classification 
>>> (what sets do well). All the SCOREC tools that are being used for 
>>> parallel adaptive simulations, and (in the past) for parallel mesh 
>>> generation, are based on a classification approach.
>>>
>>> Onkar Sahni wrote:
>>>>> So again, I go back to asking: what are the core needs that prevent us
>>>>> from using sets as both parts and partitions?  The entity set 
>>>>> mechanism
>>>>> was designed with this specific usage in mind.
>>>>
>>>> If "sets as both parts and partitions" mean using entity-sets then 
>>>> we have
>>>> already discussed this in great detail. I think the question in 
>>>> discussion
>>>> is irrespective of how one implements parts and partitions? If I
>>>> understood the question right then we need to answer queries which 
>>>> involve
>>>> a specific part and a specific entity-set (where entity-set may span 
>>>> more
>>>> than one part, may be local to a process). Now, if it is implied that
>>>> choosing entity-sets for both parts and partitions allows to use set
>>>> operations (booleans), outside the interface explicitly by 
>>>> applications,
>>>> to answer such queries well then applications might as well do it in 
>>>> other
>>>> equivalent ways (for example, loop over entities in set and ask 
>>>> residence
>>>> parts to get entities in the entity-sey belonging to a specific part).
>>>>
>>>> - Onkar
>>>>
>>>
>>>
>>
> 
> 

-- 
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"You will keep in perfect peace him whose mind is
   steadfast, because he trusts in you."               Isaiah 26:3

              Tim Tautges            Argonne National Laboratory
          (tautges at mcs.anl.gov)      (telecommuting from UW-Madison)
          phone: (608) 263-8485      1500 Engineering Dr.
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