Gram describes the structure and content of graphs, without semantics.
A graph is composed from a sequence of patterns, where each pattern is a sequence of graph elements.
The smallest graph pattern is an empty node.
()
Nodes may include properties using classic curly-braces-styled notation. This expression
is like an anonymous object that appears inside some other data structure, perhaps a list
like const people = [{name:ABK}]:
({name:"ABK"})
Nodes may self-identify themselves. This is like an object that is aware of the variable
name you've given it in a programming language -- const abk = {name:"ABK"}
(abk {name:"ABK"})
Or, the identity could be considered the representative value of the node as in these examples:
(1), (true), (`heir to the Iron Throne`)
Nodes may also provide labels to associate with other nodes. This is like having an
introspectable object in a programming language -- const abk:Person = {name:"ABK"}:
(abk:Person {name:"ABK"}), (michael:Person {name:"Michael"})
It's ok to use multiple labels, which could be subsets, singletons, or intersections:
(abk:Person:Author {name:"ABK"}), (one:Person:King:Fictional {name: "John Snow"}),
(drogon:Dragon:Fictional {name:"Drogon"})
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Annotation vs self-loop?
Q: What is the difference between an annotation and a self-loop? A: An annotation provides extra information about a single target, while a self-loop provides information about a source,target pair where either the source or target may have been different, but happen to be the same.
For example,
@physics("rigid")(a:Player)annotates a player entity with information for the physics subsystem. The information is particular to the player and not about how the player relates to itself.As a self-loop,
(a:Player)-[:MESSAGE]->(a:Player)is a message a player sent to themselves that could've been sent to another player. The message has a specific source and target, which happen to be the same.