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# weakly_connected(+Graph)

Guarantees that a directed graph Graph is weakly connected.
Graph
A graph.

## Description

Guarantees that a directed graph Graph is weakly connected, i.e., that each vertex is reachable from any other one in the underlying graph of Graph.

### Fail Conditions

Fails if Graph is not a directed graph variable or if Graph can not be constrained to be strongly connected.

## Examples

```?- weakly_connected(G).
No.

?- V`::[1,2]..[1,2,3,4], E`::[]..[[1,3],[2,4],[3,1],[4,2]], dirgraph(G,V,E), weakly_connected(G).
No.

?- V`::[]..[1,2,3], E`::[]..[[1,2],[2,1]], dirgraph(G,V,E), weakly_connected(G), graph_labeling(G).
V = []
E = []
G = dirgraph([], [])
Yes ? ;

V = [3]
E = []
G = dirgraph([3], [])
Yes ? ;

V = [2]
E = []
G = dirgraph([2], [])
Yes ? ;

V = [1]
E = []
G = dirgraph([1], [])
Yes ? ;

V = [1, 2]
E = [[2, 1]]
G = dirgraph([1, 2], [[2, 1]])
Yes ? ;

V = [1, 2]
E = [[1, 2]]
G = dirgraph([1, 2], [[1, 2]])
Yes ? ;

V = [1, 2]
E = [[1, 2], [2, 1]]
G = dirgraph([1, 2], [[1, 2], [2, 1]])
Yes
```