ILOG CPLEX 11.0 User's Manual > Advanced Programming Techniques > User-Cut and Lazy-Constraint Pools > Adding User Cuts and Lazy Constraints > Reading and Writing LP Files |
Reading and Writing LP Files |
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User cuts and lazy constraints may also be specified in LP-format files, and so may be read:
read
command
CPXreadcopyprob
of the Callable Library
IloCplex::importModel
of the C++ API
IloCplex.importModel
of the Java API
Cplex.ImportModel
of the .NET API
When CPLEX writes LP-format files, user cuts and lazy constraints added through their respective add
routines or read from LP format files will be included in the output files along with their names (if any).
The general syntax rules for LP format given in the reference manual ILOG CPLEX File Formats apply to user cuts and lazy constraints.
USER CUTS
.
LAZY CONSTRAINTS
.
These sections, and the ordinary constraints section preceded by the keywords SUBJECT TO
, can appear in any order and can be present multiple times, as long as they are placed after the objective function section and before any of the keywords BOUNDS
, GENERALS
, BINARIES
, SEMI-CONTINUOUS
or END
.
Here is an example of an LP file containing ordinary constraints and lazy constraints.
Maximize obj: 12 x1 + 5 x2 + 15 x3 + 10 x4 Subject To c1: 5 x1 + x2 + 9 x3 + 12 x4 <= 15 Lazy Constraints l1: 2 x1 + 3 x2 + 4 x3 + x4 <= 10 l2: 3 x1 + 2 x2 + 4 x3 + 10 x4 <= 8 Bounds 0 <= x1 <= 5 0 <= x2 <= 5 0 <= x3 <= 5 0 <= x4 <= 5 Generals x1 x2 x3 x4 End
ILOG CPLEX stores user cuts and lazy constraints in memory separately from ordinary constraints.
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