# bridges

A bridge in the graph can be described as an relationship which if deleted, creates two disjoint graph components. This algorithm finds bridges within the graph. It has various practical usages such as road or internet network design planning. A bridge can represent a bottleneck for many scenarios and it is valuable to detect it on time.

TraitValue
Module typealgorithm
ImplementationC++
Graph directionundirected
Edge weightsunweighted
Parallelismsequential

## Procedures

### `get()`

The procedure identifies a bridge relationship in the graph which if deleted, creates two disjoint graph components.

#### Input:

• `subgraph: Graph` (OPTIONAL) ➡ A specific subgraph, which is an object of type Graph returned by the `project()` function, on which the algorithm is run.

#### Output:

• `node_from: Vertex` ➡ Represents the first node in a bridge relationship.
• `node_to: Vertex` ➡ Represents the second node in a bridge relationship.

#### Usage:

To identify a bridge relationship in agraph, use the following query:

``````CALL bridges.get()
YIELD node_from, node_to;``````

## Example

### Database state

The database contains the following data:

Created with the following Cypher queries:

``````MERGE (a:Node {id: 1}) MERGE (b:Node {id: 0}) CREATE (a)-[:RELATION]->(b);
MERGE (a:Node {id: 2}) MERGE (b:Node {id: 0}) CREATE (a)-[:RELATION]->(b);
MERGE (a:Node {id: 2}) MERGE (b:Node {id: 1}) CREATE (a)-[:RELATION]->(b);
MERGE (a:Node {id: 0}) MERGE (b:Node {id: 3}) CREATE (a)-[:RELATION]->(b);
MERGE (a:Node {id: 3}) MERGE (b:Node {id: 4}) CREATE (a)-[:RELATION]->(b);``````

### Identify bridge relationships

Get the values using the following query:

``````CALL bridges.get() YIELD node_from, node_to
WITH node_from, node_to
MATCH (node_from)-[bridge]-(node_to)
RETURN bridge, node_from, node_to;``````

Results:

``````+-----------------+-----------------+-----------------+
| bridge          | node_from       | node_to         |
+-----------------+-----------------+-----------------+
| [:RELATION]     | (:Node {id: 3}) | (:Node {id: 4}) |
| [:RELATION]     | (:Node {id: 0}) | (:Node {id: 3}) |
+-----------------+-----------------+-----------------+``````