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Implementation of a new algorithm for generating all small, (set-inclusion) minimal k-way cuts in graphs.
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This is a proof of concept implementation of CircuitCocircuit algorithm for finding all small k-way bonds in a graph. The algorithm was devised by prof. Petr Hliněný.

A detailed description of the algorithm can be found in our paper.

Installation

With GCC >= 4.8.2:

  • Install OGDF into ~/.libs/ogdf (or elsewhere but edit Makefile)
  • Run git clone git@github.com:OndrejSlamecka/mincuts.git && cd mincuts
  • Run make, the binaries will be in bin/

To install OGDF you can do:

# install cmake, if you don't have it
mkdir ~/.libs && cd ~/.libs
git clone git@github.com:ogdf/ogdf.git && cd ogdf
ccmake . # Disable OGDF_DEBUG unless you need it
make

You may need to do git reset --HARD 6e4ba4b7f2110cbead8c426eee60a483fbe8feb0 in the OGDF directory if you have downloaded newer but incompatible version of OGDF.

Input/output file specification

Input Each line contains one edge described in format <edge id>;<source node id>;<target node id>

Output Each line contains one cut: edge indicies joined by comma (e.g. 1,2,3)

Run

Generate all 3-bonds with up to 4 edges of the road network of Zlin Region:

./bin/mincuts sample-data/zlin.csv 4 3

Overview of tools

In bin/:

mincuts

Usage:    mincuts <edge_file.csv> <cut size bound> <# of components> [-b]

    <# of components> can be exact or range (e.g. 2-3)
    -b --    use bruteforcing of all combinations instead of
            CircuitCocircuit algorithm

cutcheck

Usage:    cutcheck <edge_file.csv> [-imc, --ismincut <list>] [-cc <list>]
    [-rcc <cuts file>] [-tcc[f] <cuts file>]

    -imc    -- verifies whether <list> is a cut and a minimal one
    -cc     -- computes the number of components of G\<list>
    -rcc    -- randomized cut checker
    -tcc[f] -- total cut checker, 'f' counts all failures

*list* is a comma separated list of edge indicies.

cutdiff

Usage: cutdiff <file A with cuts> [<file B with cuts> | ~]
Output:
    * Set difference A\B (note that B\A is not computed)
    * Each cut of A and B is considered a set
    * '~' replaces second file with empty set

tester

Usage:    tester <cut size bound> <# of components>
        [-r, --randomized <# of nodes> <min>-<max edges>] [-tN]

    This program tests CircuitCocircuit implementation.
    Expects graphs in nauty's graph6 format on stdin.

    First two arguments are used for any graph being tested.
    <# of components> can be exact or range (e.g. 2-3)
    -r generate random graphs (won't use stdin input)
    <max edges> is not strict (if the random graph is disconnected
        then we add edges to connect it)
    -tN use N threads (by default N == 2)

One can use this tester with program geng from package nauty to systematically test this implementation. E.g. run geng -cq 8 | tester 4 4 to test all graphs on eight nodes. For testing bigger classes of graphs (like graphs on 10 vertices) it is recommended to use the res/mod option of geng.

cutuniq

Usage:    cutuniq <file with cuts>

        Outputs to stdout the set of cuts without permutations.

Requires the boost C++ library. Build by make cutuniq. This tool is memory efficient (at the cost of being IO expensive).


In tools/:

csv2dot.sh

Reads csv file with graph (path to file given in first argument) and prints it in the dot format (used by GraphViz).

test_on_graph.sh

Compares CircuitCocircuit implementation output with cuts computed by "brute-force" algorithm generating all combinations of edges which form a minimal cut.

geng_tester.sh

Uses tool geng from package nauty to generate all the connected graphs and passes them to tester (see above in bin/). It starts from 2 vertices and continues towards 32 vertices (which would take forever to process).

names2ids.py

Converts from ClosureSim output format to mincuts format.

./tools/names2ids.py data/zlin-silnice.csv < temp/closuresim/results-2.csv > ires-2

size_split.py

Splits mincuts results file by cut size.

graph6_to_csv.py

Reads graph in graph6 format (used by nauty) and outputs a CSV to stdout. If filepath is passed as the only parameter then the output is directed into this file.

This tool uses a bit of code from the NetworkX project, which is distributed under BSD license.

Runtime measurement related tools

  • measure_k_m_var.sh -- runs mincuts with different values of k (in k-bonds) and m (max # of elements of the k-bonds)
  • measure2tex_k_m_var.sh -- formats the output of the above tool into a TeX table
  • rtm2bonds_gen_acc_to_quartile.py -- splits the records in the output of mincuts-rtm (see below "Measure runtime") by quartiles of the time axis, sums # of bonds generated by the records grouped by ranges marked by the quartiles and outputs a TeX table

Data

Graph 5

Graph 5 is good to understand how the algorithm works. It can be found in sample-data/graph5.csv.

Graph 5

Zlín Region

Road network of the Zlín Region can be found in sample-data/zlin.csv

Getting new data from OpenStreetMap

You can export data from OpenStreetMap and process them with osm4routing to get csv file.

You will probably want to select just data relevant to you. For example extract just certain roads:

$ awk -F',' 'NR > 1 {if ($5 > "1") { print $1";"$2";"$3 }}' edges_raw.csv

This excludes edges which have 0 or 1 in the fifth column and thus are forbidden for cars or they are residential streets. See osm4routing page for detailed information.

Note that if you want to analyze the road network of anything bigger than few cities then the OSM data has the problem that each small road junction has its own node which makes analysis of anything bigger impossible. (If you solve the problem and extract a graph where each node represents a single city then let me know!)

Measure runtime

One can measure the runtime of the algorithm implementation by building the program with make mincuts-rtm (this requires the boost C++ library to be installed). All runs will then produce mincuts_rtm.log file. Each line of that file contains a record about change of state when some edge e is added to X in an extendBond call (note that if your k-bonds have k > 2 then extendBond calls are nested). Line contents (tab separated):

  • current stage of the algorithm (note j-bonds are created in stage j-1)
  • time spent in the genStage call in milliseconds
  • number of bonds generated with given X union {e}

Measure lengths of paths

Compile with make mincuts-pathslengths. mincuts will output stage number, level of genStage in the stage and length of the path between V(T_r) and V_b found by shortestPath on each line, all separated by spaces.

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