# is_dag

From igraph v1.0.0
by Gabor Csardi

##### Directed acyclic graphs

This function tests whether the given graph is a DAG, a directed acyclic graph.

- Keywords
- graphs

##### Usage

`is_dag(graph)`

##### Arguments

- graph
- The input graph. It may be undirected, in which case
`FALSE`

is reported.

##### Details

`is_dag`

checks whether there is a directed cycle in the graph. If not,
the graph is a DAG.

##### Value

- A logical vector of length one.

##### Examples

```
g <- make_tree(10)
is_dag(g)
g2 <- g + edge(5,1)
is_dag(g2)
```

*Documentation reproduced from package igraph, version 1.0.0, License: GPL (>= 2)*

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