HAC: Hybrid Access Control for Online Social Networks

Table 1

Grammar for path sentences.

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path_sentence ⩴ path_word path_word connector path_word

connector ⩴

path_word ⩴ “(” path “,” hop_count “)”

hop_count ⩴ num

Path ⩴ attr_specs attr_specs path

attr_specs ⩴ “[” rel_attr “,” pro_attr_group “]”

rel_attr ⩴ where

pro_attr_group ⩴ pro_attr_pair pro_attr_pair pro_attr_group

pro_attr_pair ⩴ “(” pro_attr_name “,” pro_attr_value “)”

pro_attr_name ⩴ PN where

pro_attr_value ⩴ PV where

num ⩴ [ - 9]+

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