README.txt file for qbsolv This directory contains the following files and directories: - README.txt: this file - License: A copy of the Apache License Version 2.0 - src: Source directory of the qbsolv program with Makefile that creates a binary read and solve "QUBO" files - doc: OpenOffice, PDF, and HTML versions of the man page, and instructions for how to change them - example: Directory of example(s) application(s) using qbsolv as a solver - tests: Directory of scripts and qubo(s) to test qbsolv - contrib.txt: Instructions for potential contributors qbsolv -i infile [-o outfile] [-m] [-T] [-n] [-S SubMatrix] [-w] [-h] [-a algorithm] [-v verbosityLevel] [-V] [-q] [-t seconds] DESCRIPTION qbsolv executes a quadratic unconstrained binary optimization (QUBO) problem represented in a file, providing bit-vector result(s) that minimizes (or optionally, maximizes) the value of the objective function represented by the QUBO. The problem is represented in the QUBO(5) file format and notably is not limited to the size or connectivity pattern of the D-Wave system on which it will be executed. The options are as follows: -i infile The name of the file in which the input QUBO resides. This is a required option. -o outfile This optional argument denotes the name of the file to which the output will be written. The default is the standard output. -a algorithm This optional argument chooses nuances of the outer loop algorithm. The default is o. 'o' for original qbsolv method. Submatrix based upon change in energy. 'p' for path relinking. Submatrix based upon differences of solutions -m This optional argument denotes to find the maximum instead of the minimum. -T target This optional argument denotes to stop execution when the target value of the objective function is found. -t timeout This optional argument stops execution when the elapsed cpu time equals or exceeds timeout value. Timeout is only checked after completion of the main loop. Other halt values such as 'target' and 'repeats' will halt before 'timeout'. The default value is 2592000.0. -n repeats This optional argument denotes, once a new optimal value is found, to repeat the main loop of the algorithm this number of times with no change in optimal value before stopping. The default value is 50. -S subproblemSize This optional argument indicates the size of the sub- problems into which the QUBO will be decomposed. A "-S 0" or "-S" argument not present indicates to use the size specified in the embedding file found in the workspace set up by DW. If a DW environment has not been established, the value will default to (47) and will use the tabu solver for subproblem solutions. If a value is specified, qbsolv uses that value to create subproblem and solve with the tabu solver. -w If present, this optional argument will print the QUBO matrix and result in .csv format. -h If present, this optional argument will print the help or usage message for qbsolv and exit without execution. -v verbosityLevel This optional argument denotes the verbosity of output. A verbosityLevel of 0 (the default) will output the number of bits in the solution, the solution, and the energy of the solution. A verbosityLevel of 1 will output the same information for multiple solutions, if found. A verbosityLevel of 2 will also output more detailed information at each step of the algorithm. This increases the output up to a value of 4. -V If present, this optional argument will emit the version number of the qbsolv program and exit without execution. -q If present, this optional argument triggers printing the format of the QUBO file. -r seed Used to reset the seed for the random number generation ------------------------ qbsolv "qubo" input file format A .qubo file contains data which describes an unconstrained quadratic binary optimization problem. It is an ASCII file comprised of four types of lines: 1) Comments - defined by a "c" in column 1. They may appear anywhere in the file, and are otherwise ignored. 2) One program line, which starts with p in the first column. The program line must be the first non-comment line in the file. The program line has six required fields (separated by space(s)), as in this example: p qubo topology maxNodes nNodes nCouplers where: p the problem line sentinel qubo identifies the file type topology a string which identifies the topology of the problem and the specific problem type. For an unconstrained problem, target will be "0" or "unconstrained." Possible, for future implementations, valid strings might include "chimera128" or "chimera512" (among others). maxNodes number of nodes in the topology. nNodes number of nodes in the problem (nNodes <= maxNodes). Each node has a unique number and must take a value in the the range {0 - (maxNodes-1)}. A duplicate node number is an error. The node numbers need not be in order, and they need not be contiguous. nCouplers number of couplers in the problem. Each coupler is a unique connection between two different nodes. The maximum number of couplers is (nNodes)^2. A duplicate coupler is an error. 3) nNodes clauses. Each clause is made up of three numbers. The numbers are separated by one or more blanks. The first two numbers must be integers and are the number for this node (repeated). The node number must be in {0 , (maxNodes-1)}. The third value is the weight associated with the node, may be an integer or float, and can take on any positive or negative value, or zero. 4) nCouplers clauses. Each clause is made up of three numbers. The numbers are separated by one or more blanks. The first two numbers must be different integers and are the node numbers for this coupler. The two values (i and j) must have (i < j). Each number must be one of the nNodes valid node numbers (and thus in {0, (maxNodes-1)}). The third value is the strength associated with the coupler, may be an integer or float, and can take on any positive or negative value, but not zero. Every node must connect with at least one other node (thus must have at least one coupler connected to it). Here is a simple QUBO file example for an unconstrained QUBO with 4 nodes and 6 couplers. This example is provided to illustrate the elements of a QUBO benchmark file, not to represent a real problem. | <--- column 1 c c This is a sample .qubo file c with 4 nodes and 6 couplers c p qubo 0 4 4 6 c ------------------ 0 0 3.4 1 1 4.5 2 2 2.1 3 3 -2.4 c ------------------ 0 1 2.2 0 2 3.4 1 2 4.5 0 3 -2 0 2 3.4 1 2 4.5 0 3 -2 1 3 4.5678 2 3 -3.22
springhser/qbsolv
Qbsolv,a decomposing solver, finds a minimum value of a large quadratic unconstrained binary optimization (QUBO) problem by splitting it into pieces solved either via a D-Wave system or a classical tabu solver. (Note that qbsolv by default uses its internal classical solver. Access to a D-Wave system must be arranged separately.)
CApache-2.0