R: List all minimum (s,t)-cuts of a graph

st_min_cuts {igraph} | R Documentation

## List all minimum (s,t)-cuts of a graph

### Description

Listing all minimum (s,t)-cuts of a directed graph, for given s and t.

### Usage

    st_min_cuts(graph, source, target, capacity = NULL)

### Arguments

`graph` | The input graph. It must be directed.
`source` | The id of the source vertex.
`target` | The id of the target vertex.
`capacity` | Numeric vector giving the edge capacities. If this is `NULL` and the graph has a `weight` edge attribute, then this attribute defines the edge capacities. For forcing unit edge capacities, even for graphs that have a `weight` edge attribute, supply `NA` here.

### Details

Given a G directed graph and two, different and non-ajacent vertices, s and t, an (s,t)-cut is a set of edges, such that after removing these edges from G there is no directed path from s to t.

The size of an (s,t)-cut is defined as the sum of the capacities (or weights) in the cut. For unweighed (=equally weighted) graphs, this is simply the number of edges.

An (s,t)-cut is minimum if it is of the smallest possible size.

### Value

A list with entries:

`value` | Numeric scalar, the size of the minimum cut(s).
`cuts` | A list of numeric vectors containing edge ids. Each vector is a minimum (s,t)-cut.
`partition1s` | A list of numeric vectors containing vertex ids, they correspond to the edge cuts. Each vertex set is a generator of the corresponding cut, i.e. in the graph G=(V,E), the vertex set X and its complementer V-X, generates the cut that contains exactly the edges that go from X to V-X.

### Author(s)

Gabor Csardi csardi.gabor@gmail.com

### References

JS Provan and DR Shier: A Paradigm for listing (s,t)-cuts in graphs, Algorithmica 15, 351–372, 1996.

### See Also

`st_cuts`, `min_separators`

### Examples

    # A difficult graph, from the Provan-Shier paper
    g <- graph_from_literal(s --+ a:b, a:b --+ t,
                   a --+ 1:2:3:4:5, 1:2:3:4:5 --+ b)
    st_min_cuts(g, source="s", target="t")

[Package igraph version 1.2.2 Index]