itaps-parallel Neighbor definition

[Tim Tautges]

A question arose in yesterday's telecon on what constitutes a part 
neighbor.  After some discussion, we came up with the following 
definition and rationale.

Def: for a given part, a part neighbor of dimension d is any other part 
which shares mesh entities of dimension d with that part (i.e. the 
entity is represented on both parts).

Rationale:
- it is desirable to tie the definition of a part neighbor with 
information intrinsic to the mesh, i.e. one could derive information 
about part neighbors using only information about the mesh entities and 
the partition of entities over processors

- in general, applications will have other criteria determining which 
other processors a given processor communicates with; that information 
can be stored in iMesh using sets and tags already, and applications 
will presumably be able to pass those things to communication functions 
in the itaps parallel interface (thus driving the application-specific 
communication patterns)

Question: are ghosted/copied entities between parts considered shared? 
I would assert that ghosting/copying should be between processors, not 
parts, so this question is not relevant with respect to part neighbors.

- tim

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"You will keep in perfect peace him whose mind is
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              Tim Tautges            Argonne National Laboratory
          (tautges at mcs.anl.gov)      (telecommuting from UW-Madison)
          phone: (608) 263-8485      1500 Engineering Dr.
            fax: (608) 263-4499      Madison, WI 53706