Transitive closure

Transitive closures of relations follow the well-known syntax of regular expressions where patterns to be repeated are enclosed in parentheses with a quantifier appended. The possible quantifiers are:

+ : 1-to-n repetitions.
* : 0-to-n repetitions.
? : 0-to-1 repetitions.
{n} : exactly n repetitions,
{n,m} : n-to-m repetitions.
{n,} : least n repetitions.

Transitive closures can be applied on combined path predicates. E.g. (-branch-> b:B (-successor->)*, (b.prod > 0))* matches all paths which traverse a branch edge and a possibly empty sequence of successor edges alternatingly. In addition, target nodes of branch edges have to be of type B and fulfill the condition b.prod > 0.

Note: Using transitive closure it is possible to find the same node several time.

Example

query	description
`A (>)+ B`	All B's that have a A above connected by one successor edges or more
`A (>)* +> B`	All B's that have a A above connected by one or more successor edges and one branch-edge directly before the B
`A ((>)* +>)+ B`	All B's conntected to A by one or more repetition of the pattern above
`A (>)* +> (>)* B`	As many sucessors followed by a branch followed by as many successors
`A (-->)* C (-->)* B`	All B' that have an ancestor of the type A and an ancestor of the type C with C between the A and the B
`A (>){2} B`	All B's conntected to an A by two incoming successor edge

GroIMP wiki

Table of Contents

Transitive closure

Example