SHAKEN Roles |
Here are some examples of Roles in SHAKEN.
You can see all the Roles currently defined in SHAKEN by expanding
Role in SHAKEN's Browse window. Just click on the
Although Roles look like regular Entities, there are
important differences:
Sometimes, however, there is such a strong association between an
Entity and the Role it is intended to play that it is natural
to say that the Entity is that Role. For example, a Fence is
intended to be a Barrier. It is natural to say that a Fence is a
Barrier (not just that Fences happen to be able to play the Role of Barrier).
For such examples in SHAKEN we say that the purpose of a Fence
is to be a Barrier in some Block:
Here is an example of a newly defined Role. The Role is Student, which
is a Role played by a Person in a Learn Event.
If the answer to these questions is "Yes", then "Flam" is probably a
Role. Here are some examples to help distinguish Roles and Entities.
Roles
SHAKEN divides the world into two major kinds of things: Entities
("things that are") and Events ("things that happen"). A Role
represents an Entity's participation in an Event.
symbol next to 'Role':
How to Use Roles in SHAKEN
Roles can be added to concept maps, just like Entities and Events.
They can be connected to Entities and Events using special relations.
Usually there are three things involved in representing a Role: the
Role itself, the Entity playing the Role and the Event in which the
Entity is playing the role. For example, to encode the knowledge that
a police car is being used as a barrier to block the road, you would
say that the PoliceCar is playing the Role of Barrier in a Block
(with a Road as object):
Defining Your Own Roles
As with Entities and Events, it's possible to define your own Roles
in SHAKEN:
Is It a Role or an Entity?
It is not always obvious whether a given concept should be defined as
a Role or simply as an Entity. Most new concepts you define will probably
be Entities. Here is a simple test to help determine if your concept may
be better encoded as a Role. For some new concept called "Flam":
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Sometimes a particular Entity is so strongly associated with its intended Role (its purpose) that the two seem indistinguishable. Here is a trickier example: