separates {RBGL} | R Documentation

## A function to test whether a subset of nodes separates two other subsets of nodes.

### Description

The function tests to see whether a set of nodes, `S1`, separates all nodes in `a` from all nodes in `b`.

### Usage

    separates(a, b, S1, g)

### Arguments

`a` | The names of the nodes in the from set.
`b` | The names of the nodes in the to set.
`S1` | The names of the nodes in the separation set.
`g` | An instance of the `graph` class. All nodes named in the other arguments must be nodes of this graph.

### Details

The algorithm is quite simple. A subgraph is created by removing the nodes named in `S1` from `g`. Then all paths between elements of `a` to elements of `b` are tested for. If any path exists the function returns `FALSE`, otherwise it returns `TRUE`.

### Value

Either `TRUE` or `FALSE` depending on whether `S1` separates `a` from `b` in `g1`.

### Author(s)

R. Gentleman

### References

S. Lauritzen, Graphical Models, OUP.

### See Also

`johnson.all.pairs.sp`

### Examples

      con <- file(system.file("XML/kmstEx.gxl",package="RBGL"))
      km <- fromGXL(con)
      close(con)

      separates("B", "A", "E", km)
      separates("B", "A", "C", km)

[Package RBGL version 1.60.0 Index]