Overview

What is SCIP?

SCIP is a framework to solve constraint integer programs (CIPs) and mixed-integer nonlinear programs. In particular,

• SCIP incorporates a mixed-integer programming (MIP) solver as well as
• an LP based mixed-integer nonlinear programming (MINLP) solver, and
• is a framework for branch-and-cut-and-price.

See the web site of SCIP for more information about licensing and to download SCIP.

If you are new to SCIP and don't know where to start you should have a look at the first steps walkthrough .

Structure of this manual

This manual gives an accessible introduction to the functionality of the SCIP code in the following chapters

Setup and news

• Installing SCIP
• Frequently Asked Questions (FAQ)
• Release notes and changes between different versions of SCIP

Tutorials and guides

• First Steps Walkthrough
• Tutorial: the interactive shell
• Important programming concepts for working with(in) SCIP
• How to start a new project
• How to search the documentation and source files structure for public interface methods
• Detailed guides for adding user plugins
• Detailed guides for advanced SCIP topics

Examples and applications

• Coding examples in C and C++ in the source code distribution
• Extensions of SCIP for specific applications

References

• Supported types of optimization problems
• Readable file formats
• Interfaces
• List of all SCIP parameters
• SCIP Authors
• License
• Links to external documentation

Quickstart

Let's consider the following minimal example in LP format. A 4-variable problem with a single, general integer variable and three linear constraints

Maximize
 obj: x1 + 2 x2 + 3 x3 + x4
Subject To
 c1: - x1 + x2 + x3 + 10 x4 <= 20
 c2: x1 - 3 x2 + x3 <= 30
 c3: x2 - 3.5 x4 = 0
Bounds
 0 <= x1 <= 40
 2 <= x4 <= 3
General
 x4
End

Saving this file as "simple.lp" allows to read it into SCIP and solve it by calling the scip binary with the -f flag to solve the problem from the provided file and exit.

scip -f simple.lp

reads and optimizes this model in no time:

SCIP version 9.1.1 [precision: 8 byte] [memory: block] [mode: optimized] [LP solver: Soplex 7.1.1] [GitHash: 006db55b1d-dirty]
Copyright (c) 2002-2024 Zuse Institute Berlin (ZIB)

External libraries: 
  Readline 8.2         GNU library for command line editing (gnu.org/s/readline)
  Soplex 7.1.1         Linear Programming Solver developed at Zuse Institute Berlin (soplex.zib.de) [GitHash: 9a11f87c]
  CppAD 20180000.0     Algorithmic Differentiation of C++ algorithms developed by B. Bell (github.com/coin-or/CppAD)
  ZLIB 1.2.13          General purpose compression library by J. Gailly and M. Adler (zlib.net)
  GMP 6.2.1            GNU Multiple Precision Arithmetic Library developed by T. Granlund (gmplib.org)
  ZIMPL 3.6.2          Zuse Institute Mathematical Programming Language developed by T. Koch (zimpl.zib.de)
  AMPL/MP 690e9e7      AMPL .nl file reader library (github.com/ampl/mp)
  PaPILO 2.3.1         parallel presolve for integer and linear optimization (github.com/scipopt/papilo)
  Nauty 2.8.8          Computing Graph Automorphism Groups by Brendan D. McKay (users.cecs.anu.edu.au/~bdm/nauty)
  sassy 1.1            Symmetry preprocessor by Markus Anders (github.com/markusa4/sassy)
  Ipopt 3.14.16        Interior Point Optimizer developed by A. Waechter et.al. (github.com/coin-or/Ipopt)

user parameter file <scip.set> not found - using default parameters


read problem <doc/inc/simpleinstance/simple.lp>
============

original problem has 4 variables (0 bin, 1 int, 0 impl, 3 cont) and 3 constraints

presolving:
(round 1, fast)       2 del vars, 1 del conss, 0 add conss, 4 chg bounds, 0 chg sides, 0 chg coeffs, 0 upgd conss, 0 impls, 0 clqs
(round 2, fast)       2 del vars, 1 del conss, 0 add conss, 6 chg bounds, 0 chg sides, 0 chg coeffs, 0 upgd conss, 0 impls, 0 clqs
(round 3, fast)       2 del vars, 1 del conss, 0 add conss, 7 chg bounds, 0 chg sides, 0 chg coeffs, 0 upgd conss, 0 impls, 0 clqs
   (0.0s) running MILP presolver
   (0.0s) MILP presolver found nothing
   (0.0s) probing cycle finished: starting next cycle
   (0.0s) symmetry computation started: requiring (bin +, int +, cont +), (fixed: bin -, int -, cont -)
   (0.0s) no symmetry present (symcode time: 0.00)
presolving (4 rounds: 4 fast, 1 medium, 1 exhaustive):
 2 deleted vars, 1 deleted constraints, 0 added constraints, 7 tightened bounds, 0 added holes, 0 changed sides, 0 changed coefficients
 2 implications, 0 cliques
presolved problem has 3 variables (1 bin, 0 int, 0 impl, 2 cont) and 2 constraints
      2 constraints of type <linear>
Presolving Time: 0.00

 time | node  | left  |LP iter|LP it/n|mem/heur|mdpt |vars |cons |rows |cuts |sepa|confs|strbr|  dualbound   | primalbound  |  gap   | compl. 
t 0.0s|     1 |     0 |     0 |     - | trivial|   0 |   3 |   2 |   0 |   0 |  0 |   0 |   0 | 1.630000e+02 | 3.400000e+01 | 379.41%| unknown
t 0.0s|     1 |     0 |     0 |     - | trivial|   0 |   3 |   2 |   0 |   0 |  0 |   0 |   0 | 1.630000e+02 | 5.300000e+01 | 207.55%| unknown
p 0.0s|     1 |     0 |     0 |     - |   locks|   0 |   3 |   2 |   2 |   0 |  0 |   0 |   0 | 1.630000e+02 | 1.225000e+02 |  33.06%| unknown
  0.0s|     1 |     0 |     2 |     - |   613k |   0 |   3 |   2 |   2 |   0 |  0 |   0 |   0 | 1.252083e+02 | 1.225000e+02 |   2.21%| unknown
  0.0s|     1 |     0 |     2 |     - |   613k |   0 |   3 |   2 |   2 |   0 |  0 |   0 |   0 | 1.252083e+02 | 1.225000e+02 |   2.21%| unknown
  0.0s|     1 |     0 |     3 |     - |   617k |   0 |   3 |   2 |   3 |   1 |  1 |   0 |   0 | 1.225000e+02 | 1.225000e+02 |   0.00%| unknown
  0.0s|     1 |     0 |     3 |     - |   617k |   0 |   3 |   2 |   3 |   1 |  1 |   0 |   0 | 1.225000e+02 | 1.225000e+02 |   0.00%| unknown

SCIP Status        : problem is solved [optimal solution found]
Solving Time (sec) : 0.00
Solving Nodes      : 1
Primal Bound       : +1.22500000000000e+02 (3 solutions)
Dual Bound         : +1.22500000000000e+02
Gap                : 0.00 %

Version

9.1.1