# is.dag

From igraph v0.6.5-2
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.

##### concept

DAG

##### Examples

```
g <- graph.tree(10)
is.dag(g)
g2 <- g + edge(5,1)
is.dag(g2)
```

*Documentation reproduced from package igraph, version 0.6.5-2, License: GPL (>= 2)*

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