Graph Pattern Notation

Graph pattern railroad diagram, a comma-separated list of PatternElement

About Notation

The GraphRAG pattern catalog uses a graph notation to describe logical graph structures called patterns that are composed of nodes, relationships and subjects.

PatternElement is a Node, Relationship or Subject

Nodes

Node is delimted by parentheses

Nodes are individual records in a graph.

(a)

• a single node identified as a

(a:Thing)

• a single node labeled as a Thing

(a:Thing:Special)

• single node with two labels

(a:Thing {k:"v"})

• labeled node with a record defining property k to be "v"

(a:Thing {k::string})

• record declaring k to be a string, but with an undefined value

(a:Thing {x@"meta"})

• record with metadata about property x
• metadata is extra information

Relationships

Relationship starts with a Node, then an Arrow followed by a Path Arrow looks like an arrow Path is either a node or a Relationship (which starts with a Node)

Relationships pair two nodes, a ‘from’ and a ‘to’ node.

(a)-[:KNOWS]->(b)

• a relationship from a to b labeled as :KNOWS

(a)-[:KNOWS {confidence:0.8}]

• a relationship with a record

Subjects

Subject is delimted by square brackets

Subjects compose multiple graph elements.

[a]

• subject about itself
• equivalent: (a)

[a | i]

• subject about another element, an “annotation”
• equivalent: (a)-->(i)

[a | i,j,k]

• a subject about 3 other elements, like set-builder notation
• equivalent: (a)-->(i), (a)-->(j), (a)-->(k)

[a |:R| i,j,k]

• a subject about 3 other elements, like set-builder notation
• equivalent: (a)-[:R]->(i), (a)-[:R]->(j), (a)-[:R]->(k)

[a:R -> i,j]

• a subject composing 2 elements into a sequence, a relationship
• equivalent: (i)-[:a:R]->(j)

[a:R {k:"v"} -> i,j,k]

• a subject composing 3 elements into a sequence, a described path
• equivalent: (i)-[a:R {k:"v"}]->(j)-[a:R {k:"v"}]->(k)

[:R {seq:1...} --> i,j,i,k]

• a described path with an applied range value
• equivalent: (i)-[:R {seq:1}]->(j)-[:R {seq:2}]->(i)-[:R {seq:3}]->(k)

[a:R {k:"v"} |-> i,j,k]

• a subject about 3 elements, which are in a sequence
• equivalent: (:a:R {k:"v"}), (a)-->(i), (a)-->(j), (a)-->(k), (i)-[a:R]->(j)-[a:R]->(k)

Further reading

• See gram-data/nearley-gram for full EBNF
• See gram-data/tree-sitter-gram for a parser