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Constraint handler for logicor constraints (equivalent to set covering, but algorithms are suited for depth first search).
- Author
- Tobias Achterberg
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Michael Winkler
This constraint handler handles a special type of linear constraints, namely logic or constraints. These are equivalent to set covering constraints, but are handled by special algorithms which are better suited for depth first search. For a set of binary variables , a logic or constraint has the form
Definition in file cons_logicor.h.
Go to the source code of this file.
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SCIP_RETCODE | SCIPincludeConshdlrLogicor (SCIP *scip) |
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SCIP_RETCODE | SCIPcreateConsLogicor (SCIP *scip, SCIP_CONS **cons, const char *name, int nvars, SCIP_VAR **vars, SCIP_Bool initial, SCIP_Bool separate, SCIP_Bool enforce, SCIP_Bool check, SCIP_Bool propagate, SCIP_Bool local, SCIP_Bool modifiable, SCIP_Bool dynamic, SCIP_Bool removable, SCIP_Bool stickingatnode) |
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SCIP_RETCODE | SCIPcreateConsBasicLogicor (SCIP *scip, SCIP_CONS **cons, const char *name, int nvars, SCIP_VAR **vars) |
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SCIP_RETCODE | SCIPaddCoefLogicor (SCIP *scip, SCIP_CONS *cons, SCIP_VAR *var) |
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int | SCIPgetNVarsLogicor (SCIP *scip, SCIP_CONS *cons) |
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SCIP_VAR ** | SCIPgetVarsLogicor (SCIP *scip, SCIP_CONS *cons) |
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SCIP_Real | SCIPgetDualsolLogicor (SCIP *scip, SCIP_CONS *cons) |
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SCIP_Real | SCIPgetDualfarkasLogicor (SCIP *scip, SCIP_CONS *cons) |
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SCIP_ROW * | SCIPgetRowLogicor (SCIP *scip, SCIP_CONS *cons) |
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creates the handler for logic or constraints and includes it in SCIP
- Parameters
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SCIP_RETCODE SCIPcreateConsLogicor |
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SCIP * |
scip, |
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SCIP_CONS ** |
cons, |
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const char * |
name, |
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int |
nvars, |
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SCIP_VAR ** |
vars, |
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SCIP_Bool |
initial, |
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SCIP_Bool |
separate, |
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SCIP_Bool |
enforce, |
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SCIP_Bool |
check, |
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SCIP_Bool |
propagate, |
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SCIP_Bool |
local, |
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SCIP_Bool |
modifiable, |
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SCIP_Bool |
dynamic, |
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SCIP_Bool |
removable, |
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SCIP_Bool |
stickingatnode |
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) |
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creates and captures a logic or constraint
- Note
- the constraint gets captured, hence at one point you have to release it using the method SCIPreleaseCons()
- Parameters
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scip | SCIP data structure |
cons | pointer to hold the created constraint |
name | name of constraint |
nvars | number of variables in the constraint |
vars | array with variables of constraint entries |
initial | should the LP relaxation of constraint be in the initial LP? Usually set to TRUE. Set to FALSE for 'lazy constraints'. |
separate | should the constraint be separated during LP processing? Usually set to TRUE. |
enforce | should the constraint be enforced during node processing? TRUE for model constraints, FALSE for additional, redundant constraints. |
check | should the constraint be checked for feasibility? TRUE for model constraints, FALSE for additional, redundant constraints. |
propagate | should the constraint be propagated during node processing? Usually set to TRUE. |
local | is constraint only valid locally? Usually set to FALSE. Has to be set to TRUE, e.g., for branching constraints. |
modifiable | is constraint modifiable (subject to column generation)? Usually set to FALSE. In column generation applications, set to TRUE if pricing adds coefficients to this constraint. |
dynamic | is constraint subject to aging? Usually set to FALSE. Set to TRUE for own cuts which are separated as constraints. |
removable | should the relaxation be removed from the LP due to aging or cleanup? Usually set to FALSE. Set to TRUE for 'lazy constraints' and 'user cuts'. |
stickingatnode | should the constraint always be kept at the node where it was added, even if it may be moved to a more global node? Usually set to FALSE. Set to TRUE to for constraints that represent node data. |
creates and captures a logicor constraint in its most basic version, i. e., all constraint flags are set to their basic value as explained for the method SCIPcreateConsLogicor(); all flags can be set via SCIPsetConsFLAGNAME-methods in scip.h
- See also
- SCIPcreateConsLogicor() for information about the basic constraint flag configuration
- Note
- the constraint gets captured, hence at one point you have to release it using the method SCIPreleaseCons()
- Parameters
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scip | SCIP data structure |
cons | pointer to hold the created constraint |
name | name of constraint |
nvars | number of variables in the constraint |
vars | array with variables of constraint entries |
adds coefficient in logic or constraint
- Parameters
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scip | SCIP data structure |
cons | logicor constraint |
var | variable to add to the constraint |
gets number of variables in logic or constraint
- Parameters
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scip | SCIP data structure |
cons | constraint data |
gets array of variables in logic or constraint
- Parameters
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scip | SCIP data structure |
cons | constraint data |
gets the dual solution of the logic or constraint in the current LP
- Parameters
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scip | SCIP data structure |
cons | constraint data |
gets the dual Farkas value of the logic or constraint in the current infeasible LP
- Parameters
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scip | SCIP data structure |
cons | constraint data |
returns the linear relaxation of the given logic or constraint; may return NULL if no LP row was yet created; the user must not modify the row!
- Parameters
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scip | SCIP data structure |
cons | constraint data |
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