# Intersyndication Ontology
#
#      Aug 19          EST 2002
#	Jan Gylta : final draft
#
#  Thu Dec 19 20:51:23 EST 2002
#	\rho : Adaption to AsTMa! 0.4

# Notes:
#
#    - the AsTMa constraints may be used by a validator to display
#      a warning/error message

#--- basic taxonomy

channel
bn: syndication channel
in: a channel can convey a set of news headline, similar to RSS

channel-item
bn: news item
in: consists usually of a title, a link forming headline information

channel-image (image)
bn: channel image
in: a channel may have a logo, usually that of the news agency

channel-ontology (ontology)
bn: channel ontology
in: a channel may also carry information according to other ontologies with it

#--- application specific constraints

# In the channel / item concept there has to be one but only one
# channel. This constraint restricts the number of channel topics to
# exactly one.

exists{1} [ * ( channel ) ] is-reified-by there-must-be-one-channel-A

there-must-be-one-channel-A (astma-constraint)
bn: There must be a channel

# The channel should also have a title, represented by the base name,
# a link to the originating site represented by an occurrence and a
# description represented by the inline description. These fields are
# however not required.

forall $t [ * ( channel ) ] 
   => suggested exists $t [ bn : *  
                            oc : ?is_url 
                            in : * ] is-reified-by channel-should-have-link-name

channel-should-have-link-name (astma-constraint)
bn: It is suggested that a channel has a title, link and description

# There can be one image present but it is not required.

exists {0,1} [ * ( channel-image ) ] is-reified-by can-be-an-image

can-be-an-image (astma-constraint)
bn: Too many images

# if it is there, it should have some information

forall $i  [ * ( channel-image ) ]
   => suggested exists $i [ bn : *
                            in : *
                            oc ( link ) : ?is_url ] is-reified-by suggest-image-data

suggest-image-data (astma-constraint)
bn: It is suggested that an image has a name, description and a link

# If it is present however, it has to be associated with the channel
# as well as have a link to the actual image.

forall [ $i ( channel-image ) ]
   => exists [ * ( channel ) ]       
      AND 
      exists [ ( is-associated-with )
               image     : $i 
               channel   : $c ] is-reified-by image-must-be-with-channel-A

image-must-be-with-channel-A (astma-constraint)
bn: Image has to be associated with the channel

# The channel, item and image can have additional properties
# associated with them. These properties exists in the form of
# associations. They must have values for its field, property,
# ontology and holder roles.

forall [ (is-property-of) ]
   => exists ] (is-property-of)
                value    : $v
                property : $p
                ontology : $o
                holder   : $h [
      AND
      (
         exists [ $h (channel) ]
         OR
         exists [ $h (channel-item) ]
         OR
         exists [ $h (channel-image) ]
      )
      AND
      exists [ $o (ontology) ] 
      AND
      exists [ $v (property-value) ]
      AND
      exists [ $p (property-field) ]is-reified-by properties-must-belong-A

properties-must-belong-A (astma-constraint)
bn: A property must be associated with a value, property, ontology and a holder topic

# Each of these topics also have to have a base name for the value

forall $t [ * ( property-value ) ] 
   => exists $t [bn: * ] is-reified-by property-must-have-value

property-must-have-value (astma-constraint)
bn: Property must have a value

forall $t  [ * ( property-field ) ]
   => exists $t [ bn: *  ] is-reified-by property-must-have-name

property-must-have-name (astma-constraint)
bn: Property must have a field name

# Each property must be associated with an ontology. These ontologies
# need a namespace in the form of an URI

forall $t [ * ( channel-ontology ) ] 
   => exists $t [ oc : ?is_uri ] is-reified-by ontology-must-have-namespace

ontology-must-have-namespace (astma-constraint)
bn: An ontology must have a namespace

# There can be any number of items.

suggested exists{0,} [ * ( channel-item ) ] is-reified-by suggest-any-number-items

suggest-any-number-items (astma-constraint)
bn: there may be any number of items

# It is also recommended that an item has a title, link and
# description.

forall $i [ * ( channel-item ) ] 
   => suggested exists $i [ bn: *  
                            oc: *  
                            in: * ] is-reified-by item-should-have-data

item-should-have-data (astma-constraint)
bn: An item should have a title, link and a description

# Each item should also be associated with the channel.

forall [ $i ( channel-item ) ] 
   => exists [ $c ( channel ) ] 
      => exists  [ (  belongs-to ) 
                   item    :  $i
                   channel :  $c ] is-reified-by item-associated-with-channel

item-associated-with-channel (astma-constraint)
bn: An item must be associated with a channel