COIN-OR: Open-source software for Operations Research


	SYMPHONY Overview (from Ted)
	SYMPHONY is a black box solver, callable library, and solver framework
	for MILPs that evolved from the COMPSys framework of Ralphs and
	Lad\'anyi \cite{ladanyi:96,ralphs:95}. The source code for packaged
	releases, with full documentation and examples, is available for
	download \cite{download.symphony:04} and is licensed under the Common
	Public License (CPL). The latest source is also available from the CVS
	repository of the COIN-OR Foundation \cite{coin:04}. SYMPHONY is fully
	documented and seven different specialized solvers built with SYMPHONY
	are available for download as examples of how to use the code. There is
	a step by step example showing how to build a simple branch-and-cut
	solver in SYMPHONY for the matching problem \cite{trick.guzelsoy:04},
	which is summarized in Section \ref{sec:case-studies}. The core solution
	methodology of SYMPHONY is a customizable branch and cut algorithm that
	can be executed sequentially or in
	parallel~\cite{ralphs.ladanyi.saltzman:03}. SYMPHONY calls on several
	other open source libraries for specific functionality, including
	COIN-OR's Cut Generation Library, Open Solver Interface, and MPS file
	parser components, GLPK's GMPL file parser, and a third-party solver for
	linear-programming problems (LPs), such as COIN-OR's LP Solver (CLP).

	There are several unique features of SYMPHONY that are worthy of
	mention. First, SYMPHONY contains a generic implementation of the WCN
	algorithm described in \cite{ralphs.saltzman.wiecek:04} for solving
	bicriteria MILPs, and methods for approximating the set of Pareto
	outcomes. The bicriteria solver can be used to examine tradeoffs
	between competing objectives, and for solving parametric MILPS, a form
	of global sensitivity analysis. SYMPHONY also contains functions for
	local sensitivity analysis based on ideas suggested by Schrage and
	Wolsey~\cite{schrage.wolsey:85}. Second, SYMPHONY has the capability to
	warm start the branch-and-bound process from a previously calculated
	branch-and-bound tree, even after modifying the problem data.
	These capabilities are described in more detail in the paper of Ralphs
	and Guzelsoy~\cite{ralphs.guzelsoy:04}. The \textbf{target audience} for
	SYMPHONY is similar to that of MINTO---users who require the power of a
	sophisticated solver framework, primarily for implementing custom branch
	and cut algorithms, with a relatively simple C-style interface, or users
	who require other advanced features such as parallelism, the ability to
	solve multi-criteria instances, or the ability to warm start solution
	procedures.

	Symphony Users
	Quite a few
	- Cincinnati Children's Hospital Research Foundation's Biomedical Informatics division. They have been using SYMPHONY for solving some bioinformatics problems.
	- I know SYMPHONY is being used by at least one airline,
	- a wireless services provider
	- a company that makes routing software,
	- a company that makes scheduling software for the mining industry,
	- and a major pharmaceutical company

	Relationship between BCP and SYMPHONy from Ted’s FAQs:
	What is the relationship of SYMPHONY and COIN/BCP? COIN/BCP is a C++ framework based roughly on an ancestor of SYMPHONY, so they take substantially the same approach and have similar functionality. COIN/BCP was developed at IBM and is currently part of the COIN-OR software repository. Currently, SYMPHONY is easier to use "out of the box" and is a better choice for beginners. It is also more efficient for performing pure branch and cut (without column generation). COIN/BCP has improved on SYMPHONY in some areas, however, such as support for branch and price. SYMPHONY's support for branch and price is limited. COIN/BCP is missing some features that SYMPHONY has, such as an implementation of global cut pools. SYMPHONY and COIN/BCP may be combined into a third-generation framework currently under development.