Mr. White,
Two points:
(1) some people use 'heterarchy' to mean exactly the same thing as
'hierarchy' and allow more than one parent for a node in a hierarchy. In
this terminology, the restriction to one parent per node defines a
'taxonomy'.
(2) since a simple label like '1.3.54.A' traces back the path into a
hierarchy, a multiple-inheritance hierarchy (heterarchy) would require that
any given node have multiple labels of that type, each being synonymous with
the other. (01)
Another tactic to avoid multiple inheritance is to use properties to
subcategorize types - logically, having multiple necessary properties is
equivalent to having multiple parent types, where each parent type is
specified solely by requiring instances to all have that property. You can
preserve the single dot-format label that way, but need an additional
mechanism to select by properties (or facets). (02)
Pat (03)
Patrick Cassidy
MICRA, Inc.
908-561-3416
cell: 908-565-4053
cassidy@xxxxxxxxx (04)
> -----Original Message-----
> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx [mailto:ontolog-forum-
> bounces@xxxxxxxxxxxxxxxx] On Behalf Of Charles P. White
> Sent: Thursday, May 01, 2008 1:58 PM
> To: [ontolog-forum]
> Subject: [ontolog-forum] Heterarchy & Hierarchy, oh my my
>
> Hello all,
>
> This is my first chime into the conversations so I hope my topic is
> appropriate.
>
> At present, I'm working as the lead of NASA/JPL's Spacecraft Problem
> Reporting System (PRS), which is a web based application where an
> engineer or scientist can report a problem with a spacecraft that is
> in-flight, or under development. When an "anomaly" is created, it is
> then automatically dispatched to the proper team of folks that can
> triage and solve the problem, sign, and close the issue.
>
> Presently, we are using a hierarchy to define the structure of the
> individual items that make up the spacecraft. It is a typical
> parent-child-grandchild relationship. However, I am running into a
> cases where a child can have more then one non-related parents. This
> aspect is something that hurts my hierarchical mind.
>
> I have recently found the concept of heterarchy in my knowledge
> management quests and find it maybe the answer. From Wikipedia, "In
> a group of related items, heterarchy is a state wherein any pair of
> items is likely to be related in two or more differing ways. Whereas
> hierarchies sort groups into progressively smaller categories and
> subcategories, heterarchies divide and unite groups variously,
> according to multiple concerns that emerge or recede from view
> according to perspective."
>
> My challenge/question is, how would define and represent the
> heterarchy in a designator system? We all know how to express
> hierarchy as 1.3.54.A for example, but when an item has more then one
> parent, how can we express that in an equally simplistic way?
>
>
> Thanks for the bandwidth
> Charles P. White (aka Jet Burns)
> "This sentense has three erors."
>
>
>
>
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