# is_dag

From igraph v1.2.2
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.

##### Examples

```
# NOT RUN {
g <- make_tree(10)
is_dag(g)
g2 <- g + edge(5,1)
is_dag(g2)
# }
```

*Documentation reproduced from package igraph, version 1.2.2, License: GPL (>= 2)*

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