## Description

This function implements algorithm 4.2.1 of Gross and Yellen. The
input is a `graph`

and a `node`

to start from. It returns a
standard vertex labeling of `graph`

. This is a vector with
elements corresponding to the nodes of `graph`

and with values
that correspond to point in the depth first search the node is
visited.
## Usage

DFS(object, node, checkConn=TRUE)

## Arguments

object

An instance of the `graph`

class.

node

A `character`

indicating the starting node.

checkConn

A `logical`

indicating whether the connectivity
of the graph should be checked.

## Value

A vector with names given by the nodes of `graph`

whose values
are `0`

to one less than the number of nodes. These indices
indicate the point at which the node will be visited.

## Details

This function implements algorithm 4.2.1 of Gross and Yellen. Specific
details are given there. It requires that the graph be connected. By default, this is checked,
but since the checking can be expensive it is optional.

A faster and mostly likely better implementation of depth first
searching is given by `dfs`

in the RBGL
package.

## References

*Graph Theory and its Applications*, J. Gross and J. Yellen. ## Examples

RNGkind("Mersenne-Twister")
set.seed(123)
g1 <- randomGraph(letters[1:10], 1:4, p=.3)
RNGkind()
DFS(g1, "a")