| Ontology for self-describing networks | S-TEN D2.1 |
S-TEN uses the "possible future worlds" approach to the concept of "can". That something can happen is interpreted as meaning that it does happen in at least one possible future world.
Consider the class C_AM_WC-T_L123, as defined in The class of wind chill information. "WS_123 can do C_AM_WC-T_L123" means:
some of the possible members of C_AM_WC-T_L123 are performed by WS_123.
This can be stated using OWL as follows:
:WS_123 a [ owl:onProperty sten:performs ;
owl:someValuesFrom
[ owl:intersectionOf
( sten:possible
:C_AM_WC-T_L123
)
]
] .
Unfortunately this statement merely says that WS_123 can do a member of C_AM_WC-T_L123. It is not possible to deduce from this whether or not WS_123 can perform a member of C_AM_WC-T_L123_T456, which is the subclass of C_AM_WC-T_L123 defined by specifying a time period as follows:
:C_AM_WC-T_L123_T456 =
[ owl:intersectionOf
( :C_AM_WC-T_L123
[ owl:onProperty sten:during ;
owl:allValuesFrom [ rdfs:comment "a set of possible periods is defined" ]
]
)
] .
In order to make this deduction, a stronger version of "can" is required for which "WS_123 can do C_AM_WC-T_L123" means:
for any subclass of the possible members of C_AM_WC-T_L123 defined as an plan, some are performed by WS_123.
This statement is difficult to make in OWL, so a shorthand is defined as follows:
:WS_123 sten:can_do_plan_within :C_AM_WC-T_L123 .
If something is inevitable, then it happens in all future possible worlds.
Consider the ball intended by Prince Charming. "It is inevitable that Cinderella attends the ball" means:
Cinderella attends each the ball intended by Prince Charming in each possible future world.
:intended_by_PC = [ owl:onProperty sten:intended_by
owl:allValuesFrom :Prince_Charming ] .
:PCs_Ball rdfs:subClassOf ont:ball ;
rdfs:subClassOf :intended_by_PC .
:possible_PCs_Ball = [ owl:intersectionOf
( sten:possible
:PCs_Ball
)
] .
:possible_PCs_Ball rdfs:subClassOf [ owl:onProperty ont:attended_by ;
owl:someValuesFrom [ owl:oneOf ( :Cinderella ) ]
] .
As discussed in Meaning of "can", the weaker statement "Cinderella can attend the ball" means:
Cinderella attends the ball intended by Prince Charming in some possible future worlds.
:intended_by_PC = [ owl:onProperty sten:intended_by
owl:allValuesFrom :Prince_Charming ] .
:PCs_Ball rdfs:subClassOf ont:ball ;
rdfs:subClassOf :intended_by_PC .
:possible_PCs_Ball = [ owl:intersectionOf
( sten:possible
:PCs_Ball
)
] .
:Cinderella a [ owl:onProperty ont:attends ;
owl:someValuesFrom :possible_PCs_Ball ] .
The statement "Cinderella shall go to the ball" made by the Fairy Godmother means:
Cinderella attends the ball intended by Prince Charming, where the intension is refined by the Fairy Godmother, in each future world.
:intended_by_PC = [ owl:onProperty sten:intended_by
owl:allValuesFrom :Prince_Charming ] .
:intended_by_FG = [ owl:onProperty sten:intended_by
owl:allValuesFrom :Fairy_Godmother ] .
:PCs_Ball rdfs:subClassOf ont:ball ;
rdfs:subClassOf :intended_by_PC .
:FGs_Ball rdfs:subClassOf :PCs_Ball ;
rdfs:subClassOf :intended_by_FG .
:FGs_Ball rdfs:subClassOf [ owl:onProperty ont:attended_by ;
owl:someValuesFrom [ owl:oneOf ( :Cinderella ) ]
] .
The class of sten:device "pump" consists of all objects which are intended by the sten:device_supplier to perform a member of the class of sten:activity "pumping". It is the intension that is important, because a "pump" might never actually perform a "pumping" activity.
Hence the class of device "pump" can be defined from the class of activity "pumping" as follows:
:device_supplier_intended_pumping =
[ owl:intersectionOf
( :pumping
[ owl:onProperty sten:intended_by ;
owl:allValuesFrom sten:device_supplier ]
sten:possible
)
] .
:pump = [ owl:onProperty sten:performs ;
owl:someValuesFrom :device_supplier_intended_pumping ] .
In an emergency, a large heavy pump can be used as an anchor. A intension to do this is formed by a captain of a ship rather than a sten:device_supplier.
An object is a sten:possible if and only if it exists in a possible world.
OWL specification:
--> <owl:Class rdf:about="&sten;possible"> <rdfs:subClassOf rdf:resource="&sten;classical_object"/> <meta:defined_by rdf:resource="&D2.1;/what_is_possible.htm#possible"/> </owl:Class> <!--
An object is an sten:intended_by relationship if and only if:
OWL specification:
--> <owl:ObjectProperty rdf:about="&sten;intended_by"> <rdfs:domain rdf:resource="&sten;classical_object"/> <rdfs:range rdf:resource="&sten;classical_object"/> <meta:defined_by rdf:resource="&D2.1;/what_is_possible.htm#intended_by"/> </owl:ObjectProperty> <!--
An object is an sten:can_do_plan_within relationship if and only if:
A plan is a subclass of sten:activity which is defined so that each member satisfies a requirement. A plan may contain many possible instances of sten:activity. A plan is fulfilled if one of them happens.
NOTE 1 This relationship implies that some subclasses cannot be defined as a plan. This restriction enables the statement such as "device D can perform any plan within subclass A".
NOTE 2 This is very sordid. It says merely "if you choose D for a plan within subclass A nobody can blame you". If would be good to have something more formal.
OWL specification:
--> <owl:ObjectProperty rdf:about="&sten;can_do_plan_within"> <rdfs:domain rdf:resource="&sten;classical_object"/> <rdfs:range> <owl:Restriction> <owl:onProperty rdf:resource="rdfs;subClassOf"/> <owl:someValuesFrom rdf:resource="sten:activity"/> </owl:Restriction> </rdfs:range> <meta:defined_by rdf:resource="&D2.1;/what_is_possible.htm#can_do_plan_within"/> </owl:ObjectProperty> <!--
© S-TEN Association e.V. — Public deliverable of the S-TEN project