davidzemancz / mff-linprog

Intro

Program for generating MathProg scripts for glpk solver.

Requirements

• .NET SDK for .NET 6 needed for build.

Usage

• Use linprog vstup-XXX.txt vystup-XXX.mod -d -r command.
• In general linprog [-h --help] [inputFileName] [outputFileName] [-r --run] [-d --debug].
• If outputFileName is not specified, output.mod is used.

Build

• Use dotnet build command.
• Program builds to ./bin/Debug/net6.0/ directory

Options

• -h|--help - Display help informations.
• -r|--run - Run glpsol automatically.
• -d|--debug - Display debug informations during run.

Program structure

• Program
  • Main(string[] args) : void - Entry point.
  • WriteHelpInfo() : void - Write help informations to output.
  • ReadWeightedDirectedGraph(string firstLine, StreamReader reader) : Graph - Read input to Graph object instance and return it.
  • WriteGlpkScript(Graph graph, StreamWriter writer) : void - Write data from Graph instance to .mod file using MathProg language.
  • RunGlpSol(string outputFile) : void - Automatically run glpsol -m outputFile.mod command.
• Graph
  • Directed graph object that stores dictionary of vertices and of their neighbors.
• Vertex
  • Only holds its Id.
• Edge
  • Oriented edge object that holds its first and second vertex.

Output

• set Edges := {(v1,v2,weight),...}; - List of edges.
• var r{(i, j, w) in Edges}, >= 0, <=1, integer; - Variable r(i,j,w) for each edge in {0,1} indicating, whether edge shoud be removed or not.
• minimize obj: sum{(i, j, w) in Edges} r[i, j, w]*w; - Minimizing objective function.
• c0: r[v1,v2,w1] + r[v2,v3,w2] + r[v3,v1,w3] >= 1; - Condition for each cycle of lenth three of four. Means that at least one edge must be removed (r[v1,v2,w] set to 1).