lpexact.h

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/*         SCIP --- Solving Constraint Integer Programs                      */
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/*  Copyright (c) 2002-2025 Zuse Institute Berlin (ZIB)                      */
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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
 
/**@file   lpexact.h
 * @ingroup INTERNALAPI
 * @brief  internal methods for exact LP management
 * @author Leon Eifler
 */
 
/*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/
 
#ifndef __SCIP_LPEXACT_H__
#define __SCIP_LPEXACT_H__
 
 
#include <stdio.h>
 
#include "scip/def.h"
#include "blockmemshell/memory.h"
#include "scip/rational.h"
#include "scip/type_event.h"
#include "scip/type_lpexact.h"
#include "scip/type_misc.h"
#include "scip/type_prob.h"
#include "scip/type_rational.h"
#include "scip/type_set.h"
#include "scip/type_stat.h"
#include "scip/type_sol.h"
#include "scip/type_var.h"
#include "scip/pub_lpexact.h"
 
#ifdef __cplusplus
extern "C" {
#endif
 
/*
 * Column methods
 */
 
/** creates an LP column */
SCIP_RETCODE SCIPcolExactCreate(
   SCIP_COLEXACT**       col,                /**< pointer to column data */
   SCIP_COL*             fpcol,              /**< the corresponding fp col */
   BMS_BLKMEM*           blkmem,             /**< block memory */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_STAT*            stat,               /**< problem statistics */
   SCIP_VAR*             var,                /**< variable, this column represents */
   int                   len,                /**< number of nonzeros in the column */
   SCIP_ROWEXACT**       rows,               /**< array with rows of column entries */
   SCIP_RATIONAL**       vals,               /**< array with coefficients of column entries */
   SCIP_Bool             removable           /**< should the column be removed from the LP due to aging or cleanup? */
   );
 
/** frees an LP column */
SCIP_RETCODE SCIPcolExactFree(
   SCIP_COLEXACT**       col,                /**< pointer to LP column */
   BMS_BLKMEM*           blkmem              /**< block memory */
   );
 
/** output column to file stream */
void SCIPcolExactPrint(
   SCIP_COLEXACT*        col,                /**< LP column */
   SCIP_MESSAGEHDLR*     messagehdlr,        /**< message handler */
   FILE*                 file                /**< output file (or NULL for standard output) */
   );
 
/** adds a previously non existing coefficient to an LP column */
SCIP_RETCODE SCIPcolExactAddCoef(
   SCIP_COLEXACT*        col,                /**< LP column */
   BMS_BLKMEM*           blkmem,             /**< block memory */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_EVENTQUEUE*      eventqueue,         /**< event queue */
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_ROWEXACT*        row,                /**< LP row */
   SCIP_RATIONAL*        val                 /**< value of coefficient */
   );
 
/** deletes coefficient from column */
SCIP_RETCODE SCIPcolExactDelCoef(
   SCIP_COLEXACT*        col,                /**< column to be changed */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_ROWEXACT*        row                 /**< coefficient to be deleted */
   );
 
/** changes or adds a coefficient to an LP column */
SCIP_RETCODE SCIPcolExactChgCoef(
   SCIP_COLEXACT*        col,                /**< LP column */
   BMS_BLKMEM*           blkmem,             /**< block memory */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_EVENTQUEUE*      eventqueue,         /**< event queue */
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_ROWEXACT*        row,                /**< LP row */
   SCIP_RATIONAL*        val                 /**< value of coefficient */
   );
 
/** increases value of an existing or nonexisting coefficient in an LP column */
SCIP_RETCODE SCIPcolExactIncCoef(
   SCIP_COLEXACT*        col,                /**< LP column */
   BMS_BLKMEM*           blkmem,             /**< block memory */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_EVENTQUEUE*      eventqueue,         /**< event queue */
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_ROWEXACT*        row,                /**< LP row */
   SCIP_RATIONAL*        incval              /**< value to add to the coefficient */
   );
 
/** changes objective value of column */
SCIP_RETCODE SCIPcolExactChgObj(
   SCIP_COLEXACT*        col,                /**< LP column to change */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_RATIONAL*        newobj              /**< new objective value */
   );
 
/** changes lower bound of column */
SCIP_RETCODE SCIPcolExactChgLb(
   SCIP_COLEXACT*        col,                /**< LP column to change */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_RATIONAL*        newlb               /**< new lower bound value */
   );
 
/** changes upper bound of column */
SCIP_RETCODE SCIPcolExactChgUb(
   SCIP_COLEXACT*        col,                /**< LP column to change */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_RATIONAL*        newub               /**< new upper bound value */
   );
 
/*
 * Row methods
 */
 
/** increases usage counter of LP row */
void SCIProwExactCapture(
   SCIP_ROWEXACT*        row                 /**< LP row */
   );
 
/** output column to file stream */
void SCIProwExactPrint(
   SCIP_ROWEXACT*        row,                /**< LP row */
   SCIP_MESSAGEHDLR*     messagehdlr,        /**< message handler */
   FILE*                 file                /**< output file (or NULL for standard output) */
   );
 
/** get the index of an exact row */
int SCIProwExactGetIndex(
   SCIP_ROWEXACT*        row                 /**< LP row */
   );
 
/** return TRUE iff row is modifiable */
SCIP_Bool SCIProwExactIsModifiable(
   SCIP_ROWEXACT*        row                 /**< LP row */
   );
 
/** returns true, if an exact row for this fprow was already created */
SCIP_Bool SCIProwHasExRow(
   SCIP_LPEXACT*         lpexact,            /**< exact lp data structure */
   SCIP_ROW*             row                 /**< SCIP row */
   );
 
/** changes left hand side of exact LP row */
SCIP_RETCODE SCIProwExactChgLhs(
   SCIP_ROWEXACT*        rowexact,           /**< exact LP row */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_LPEXACT*         lpexact,            /**< current exact LP data */
   SCIP_RATIONAL*        lhs                 /**< new left hand side */
   );
 
/** changes right hand side of exact LP row */
SCIP_RETCODE SCIProwExactChgRhs(
   SCIP_ROWEXACT*        rowexact,           /**< exact LP row */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_LPEXACT*         lpexact,            /**< current exact LP data */
   SCIP_RATIONAL*        rhs                 /**< new right hand side */
   );
 
/** returns exact col corresponding to fpcol, if it exists. Otherwise returns NULL */
SCIP_COLEXACT* SCIPcolGetColExact(
   SCIP_COL*             col                 /**< SCIP col */
   );
 
/** calculates the Farkas coefficient or reduced cost of a column i using the given dual Farkas vector y */
SCIP_RETCODE SCIPcolExactCalcFarkasRedcostCoef(
   SCIP_COLEXACT*        col,                /**< LP column */
   SCIP_SET*             set,                /**< SCIP settings pointer */
   SCIP_RATIONAL*        result,             /**< rational to store the result */
   SCIP_RATIONAL**       dual,               /**< dense dual Farkas vector, NULL to use internal row-values */
   SCIP_Bool             usefarkas           /**< should the farkas coefficient be computed ? */
   );
 
/** creates and captures an LP row */
SCIP_RETCODE SCIProwExactCreate(
   SCIP_ROWEXACT**       row,                /**< pointer to LP row data */
   SCIP_ROW*             fprow,              /**< corresponding fp row */
   SCIP_ROW*             fprowrhs,           /**< rhs-part of fp-relaxation of this row if necessary, NULL otherwise */
   BMS_BLKMEM*           blkmem,             /**< block memory */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_STAT*            stat,               /**< problem statistics */
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   int                   len,                /**< number of nonzeros in the row */
   SCIP_COLEXACT**       cols,               /**< array with columns of row entries */
   SCIP_RATIONAL**       vals,               /**< array with coefficients of row entries */
   SCIP_RATIONAL*        lhs,                /**< left hand side of row */
   SCIP_RATIONAL*        rhs,                /**< right hand side of row */
   SCIP_Bool             isfprelaxable       /**< is it possible to make fp-relaxation of this row */
   );
 
/** creates and captures an exact LP row from a fp row
 *
 *  @note This may change the floating-point coefficients slightly if the rational representation is rounded to smaller
 *  denominators according to parameter exact/cutmaxdenom.
 */
SCIP_RETCODE SCIProwExactCreateFromRow(
   SCIP_ROW*             fprow,              /**< corresponding fp row to create from */
   BMS_BLKMEM*           blkmem,             /**< block memory */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_STAT*            stat,               /**< problem statistics */
   SCIP_EVENTQUEUE*      eventqueue,         /**< the eventqueue */
   SCIP_PROB*            prob,               /**< scip prob structure */
   SCIP_LPEXACT*         lpexact             /**< current LP data */
   );
 
/** populate data of two empty fp rows with data from exact row */
SCIP_RETCODE SCIProwExactGenerateFpRows(
   BMS_BLKMEM*           blkmem,             /**< block memory */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_STAT*            stat,               /**< SCIP statistics */
   SCIP_EVENTQUEUE*      eventqueue,         /**< event queue */
   SCIP_LPEXACT*         lpexact,            /**< current exact LP data */
   SCIP_PROB*            prob,               /**< SCIP problem data */
   SCIP_ROWEXACT*        row,                /**< SCIP row */
   SCIP_ROW*             rowlhs,             /**< fp row-relaxation wrt lhs */
   SCIP_ROW*             rowrhs,             /**< fp row-relaxation wrt rhs */
   SCIP_Bool*            onerowrelax,        /**< is one row enough to represent the exact row */
   SCIP_Bool*            hasfprelax          /**< is it possible to generate relaxations at all for this row? */
   );
 
/** applies all cached changes to the LP solver */
SCIP_RETCODE SCIPlpExactFlush(
   SCIP_LPEXACT*         lpexact,            /**< current exact LP data */
   BMS_BLKMEM*           blkmem,             /**< block memory */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_EVENTQUEUE*      eventqueue          /**< event queue */
   );
 
/** ensures all rows/columns are correctly updated, but changes are not yet communicated to the exact LP solver */
SCIP_RETCODE SCIPlpExactLink(
   SCIP_LPEXACT*         lpexact,            /**< current exact LP data */
   BMS_BLKMEM*           blkmem,             /**< block memory */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_EVENTQUEUE*      eventqueue          /**< event queue */
   );
 
/*
 * lp methods
 */
 
/** returns whether the success rate of the Neumaier-Shcherbina safe bounding method is sufficiently high */
SCIP_Bool SCIPlpExactBoundShiftUseful(
   SCIP_LPEXACT*         lpexact             /**< pointer to LP data object */
   );
 
/** returns whether it is possible to use project and shift bounding method */
SCIP_Bool SCIPlpExactProjectShiftPossible(
   SCIP_LPEXACT*         lpexact             /**< pointer to LP data object */
   );
 
/** checks that lp and fplp are properly synced */
SCIP_Bool SCIPlpExactIsSynced(
   SCIP_LPEXACT*         lpexact,            /**< pointer to LP data object */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_MESSAGEHDLR*     msg                 /**< message handler */
   );
 
/** creates empty LP data object */
SCIP_RETCODE SCIPlpExactCreate(
   SCIP_LPEXACT**        lpexact,            /**< pointer to LP data object */
   BMS_BLKMEM*           blkmem,             /**< block memory */
   SCIP_LP*              fplp,               /**< the normal floating point lp */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_MESSAGEHDLR*     messagehdlr,        /**< message handler */
   SCIP_STAT*            stat,               /**< problem statistics */
   const char*           name                /**< problem name */
   );
 
/** frees LP data object */
SCIP_RETCODE SCIPlpExactFree(
   SCIP_LPEXACT**        lpexact,            /**< pointer to LP data object */
   BMS_BLKMEM*           blkmem,             /**< block memory */
   SCIP_SET*             set                 /**< global SCIP settings */
   );
 
/** adds a column to the LP and captures the variable */
SCIP_RETCODE SCIPlpExactAddCol(
   SCIP_LPEXACT*         lpexact,            /**< LP data */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_COLEXACT*        col                 /**< LP column */
   );
 
/** adds a row to the LP and captures it */
SCIP_RETCODE SCIPlpExactAddRow(
   SCIP_LPEXACT*         lpexact,            /**< LP data */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_ROWEXACT*        rowexact            /**< LP row */
   );
 
/** returns the feasibility of a row for the given solution */
SCIP_RETCODE SCIProwExactGetSolFeasibility(
   SCIP_ROWEXACT*        row,                /**< LP row */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_STAT*            stat,               /**< problem statistics data */
   SCIP_SOL*             sol,                /**< primal CIP solution */
   SCIP_RATIONAL*        result              /**< result pointer */
   );
 
/** does activity computation with running error analysis for a row, return TRUE on success */
SCIP_Bool SCIProwExactGetSolActivityWithErrorbound(
   SCIP_ROWEXACT*        rowexact,           /**< LP row */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_STAT*            stat,               /**< problem statistics data */
   SCIP_SOL*             sol,                /**< primal CIP solution */
   SCIP_Real*            activity,           /**< the approximate activity */
   SCIP_Real*            errorbound          /**< the error bound */
   );
 
/** returns the activity of a row for a given solution */
SCIP_RETCODE SCIProwExactGetSolActivity(
   SCIP_ROWEXACT*        rowexact,           /**< LP row */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_STAT*            stat,               /**< problem statistics data */
   SCIP_SOL*             sol,                /**< primal CIP solution */
   SCIP_Bool             useexact,           /**< should an exact solution be used */
   SCIP_RATIONAL*        result              /**< resulting activity */
   );
 
/** decreases usage counter of LP row, and frees memory if necessary */
SCIP_RETCODE SCIProwExactRelease(
   SCIP_ROWEXACT**       row,                /**< pointer to LP row */
   BMS_BLKMEM*           blkmem,             /**< block memory */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_LPEXACT*         lpexact             /**< current LP data */
   );
 
/** frees an LP row */
SCIP_RETCODE SCIProwExactFree(
   SCIP_ROWEXACT**       row,                /**< pointer to LP row */
   BMS_BLKMEM*           blkmem,             /**< block memory */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_LPEXACT*         lpexact             /**< current LP data */
   );
 
/** ensuresr, that column array of row can store at least num entries */
SCIP_RETCODE SCIProwExactEnsureSize(
   SCIP_ROWEXACT*        row,                /**< LP row */
   BMS_BLKMEM*           blkmem,             /**< block memory */
   SCIP_SET*             set,                /**< global SCIP settings */
   int                   num                 /**< minimum number of entries to store */
   );
 
/** add constant value to a row */
SCIP_RETCODE SCIProwExactAddConstant(
   SCIP_ROWEXACT*        row,                /**< LP row */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_STAT*            stat,               /**< problem statistics */
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_RATIONAL*        addval              /**< constant value to add to the row */
   );
 
/** adds a previously non existing coefficient to an LP row */
SCIP_RETCODE SCIProwExactAddCoef(
   SCIP_ROWEXACT*        rowexact,           /**< LP row */
   BMS_BLKMEM*           blkmem,             /**< block memory */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_EVENTQUEUE*      eventqueue,         /**< event queue */
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_COLEXACT*        colexact,           /**< LP column */
   SCIP_RATIONAL*        val                 /**< value of coefficient */
   );
 
/** deletes coefficient from row */
SCIP_RETCODE SCIProwExactDelCoef(
   SCIP_ROWEXACT*        row,                /**< row to be changed */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_COLEXACT*        col                 /**< coefficient to be deleted */
   );
 
/** changes or adds a coefficient to an LP row */
SCIP_RETCODE SCIProwExactChgCoef(
   SCIP_ROWEXACT*        row,                /**< LP row */
   BMS_BLKMEM*           blkmem,             /**< block memory */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_EVENTQUEUE*      eventqueue,         /**< event queue */
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_COLEXACT*        col,                /**< LP column */
   SCIP_RATIONAL*        val                 /**< value of coefficient */
   );
 
/** increases value of an existing or nonexisting coefficient in an LP column */
SCIP_RETCODE SCIProwExactIncCoef(
   SCIP_ROWEXACT*        row,                /**< LP row */
   BMS_BLKMEM*           blkmem,             /**< block memory */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_EVENTQUEUE*      eventqueue,         /**< event queue */
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_COLEXACT*        col,                /**< LP column */
   SCIP_RATIONAL*        incval              /**< valpelue to add to the coefficient */
   );
 
/** changes constant value of a row */
SCIP_RETCODE SCIProwExactChgConstant(
   SCIP_ROWEXACT*        row,                /**< LP row */
   SCIP_STAT*            stat,               /**< problem statistics */
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_RATIONAL*        constant            /**< new constant value */
   );
 
/** returns the feasibility of a row in the current LP solution: negative value means infeasibility */
SCIP_RETCODE SCIProwExactGetLPFeasibility(
   SCIP_ROWEXACT*        row,                /**< LP row */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_STAT*            stat,               /**< problem statistics */
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_RATIONAL*        result              /**< rational pointer to store the result */
   );
 
/** returns the pseudo feasibility of a row in the current pseudo solution: negative value means infeasibility */
SCIP_RETCODE SCIProwExactGetPseudoFeasibility(
   SCIP_ROWEXACT*        row,                /**< LP row */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_STAT*            stat,               /**< problem statistics */
   SCIP_RATIONAL*        result              /**< rational pointer to store the result */
   );
 
/** returns the activity of a row in the current LP solution */
SCIP_RATIONAL* SCIProwExactGetLPActivity(
   SCIP_ROWEXACT*        row,                /**< LP row */
   SCIP_STAT*            stat,               /**< problem statistics */
   SCIP_LPEXACT*         lpexact             /**< current LP data */
   );
 
/** returns the pseudo activity of a row in the current pseudo solution */
SCIP_RATIONAL* SCIProwExactGetPseudoActivity(
   SCIP_ROWEXACT*        row,                /**< LP row */
   SCIP_STAT*            stat                /**< problem statistics */
   );
 
/** enables delaying of row sorting */
void SCIProwExactDelaySort(
   SCIP_ROWEXACT*        rowexact            /**< LP rowexact */
   );
 
/** disables delaying of row sorting, sorts row and merges coefficients with equal columns */
void SCIProwExactForceSort(
   SCIP_ROWEXACT*        rowexact,           /**< LP rowexact */
   SCIP_SET*             set                 /**< global SCIP settings */
   );
 
/** recalculates the current activity of a row */
void SCIProwExactRecalcLPActivity(
   SCIP_ROWEXACT*        rowexact,           /**< LP row */
   SCIP_STAT*            stat                /**< problem statistics */
   );
 
 /** calculates the current pseudo activity of a row */
void SCIProwExactRecalcPseudoActivity(
   SCIP_ROWEXACT*        rowexact,           /**< row data */
   SCIP_STAT*            stat                /**< problem statistics */
   );
 
/** gets objective value of column */
SCIP_RATIONAL* SCIPcolExactGetObj(
   SCIP_COLEXACT*        col                 /**< LP column */
   );
 
/** gets lower bound of column */
SCIP_RATIONAL* SCIPcolExactGetLb(
   SCIP_COLEXACT*        col                 /**< LP column */
   );
 
/** gets upper bound of column */
SCIP_RATIONAL* SCIPcolExactGetUb(
   SCIP_COLEXACT*        col                 /**< LP column */
   );
 
/** gets best bound of column with respect to the objective function */
SCIP_RATIONAL* SCIPcolExactGetBestBound(
   SCIP_COLEXACT*        col                 /**< LP column */
   );
 
/** gets the primal LP solution of a column */
SCIP_RATIONAL* SCIPcolExactGetPrimsol(
   SCIP_COLEXACT*        col                 /**< LP column */
   );
 
/*
 * lp update methods
 */
 
/** updates current pseudo and loose objective value for a change in a variable's objective value */
SCIP_RETCODE SCIPlpExactUpdateVarObj(
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_VAR*             var,                /**< problem variable that changed */
   SCIP_RATIONAL*        oldobj,             /**< old objective value of variable */
   SCIP_RATIONAL*        newobj              /**< new objective value of variable */
   );
 
/** updates current root pseudo objective value for a global change in a variable's lower bound */
SCIP_RETCODE SCIPlpExactUpdateVarLbGlobal(
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_VAR*             var,                /**< problem variable that changed */
   SCIP_RATIONAL*        oldlb,              /**< old lower bound of variable */
   SCIP_RATIONAL*        newlb               /**< new lower bound of variable */
   );
 
/** updates current pseudo and loose objective value for a change in a variable's lower bound */
SCIP_RETCODE SCIPlpExactUpdateVarLb(
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_VAR*             var,                /**< problem variable that changed */
   SCIP_RATIONAL*        oldlb,              /**< old lower bound of variable */
   SCIP_RATIONAL*        newlb               /**< new lower bound of variable */
   );
 
/** updates current root pseudo objective value for a global change in a variable's upper bound */
SCIP_RETCODE SCIPlpExactUpdateVarUbGlobal(
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_VAR*             var,                /**< problem variable that changed */
   SCIP_RATIONAL*        oldub,              /**< old upper bound of variable */
   SCIP_RATIONAL*        newub               /**< new upper bound of variable */
   );
 
/** updates current pseudo objective value for a change in a variable's upper bound */
SCIP_RETCODE SCIPlpExactUpdateVarUb(
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_VAR*             var,                /**< problem variable that changed */
   SCIP_RATIONAL*        oldub,              /**< old upper bound of variable */
   SCIP_RATIONAL*        newub               /**< new upper bound of variable */
   );
 
/** informs LP, that given variable was added to the problem */
SCIP_RETCODE SCIPlpExactUpdateAddVar(
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_VAR*             var                 /**< variable that is now a LOOSE problem variable */
   );
 
/** informs LP, that given variable is to be deleted from the problem */
SCIP_RETCODE SCIPlpExactUpdateDelVar(
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_VAR*             var                 /**< variable that will be deleted from the problem */
   );
 
/** informs LP, that given formerly loose problem variable is now a column variable */
SCIP_RETCODE SCIPlpExactUpdateVarColumn(
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_VAR*             var                 /**< problem variable that changed from LOOSE to COLUMN */
   );
 
/** informs LP, that given formerly column problem variable is now again a loose variable */
SCIP_RETCODE SCIPlpExactUpdateVarLoose(
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_VAR*             var                 /**< problem variable that changed from COLUMN to LOOSE */
   );
 
/** decrease the number of loose variables by one */
void SCIPlpExactDecNLoosevars(
   SCIP_LPEXACT*         lpexact             /**< current LP data */
   );
 
int SCIPlpExactGetNRows(
   SCIP_LPEXACT*         lpexact             /**< current LP data */
   );
 
/** stores the LP solution in the columns and rows */
SCIP_RETCODE SCIPlpExactGetSol(
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_STAT*            stat,               /**< problem statistics */
   SCIP_Bool*            primalfeasible,     /**< pointer to store whether the solution is primal feasible, or NULL */
   SCIP_Bool*            dualfeasible,       /**< pointer to store whether the solution is dual feasible, or NULL */
   SCIP_Bool             overwritefplp       /**< should the floating point values be overwritten, e.g. if fp lp was infeasible */
   );
 
/** stores LP solution with infinite objective value in the columns and rows */
SCIP_RETCODE SCIPlpExactGetUnboundedSol(
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_STAT*            stat,               /**< problem statistics */
   SCIP_Bool*            primalfeasible,     /**< pointer to store whether the solution is primal feasible, or NULL */
   SCIP_Bool*            rayfeasible         /**< pointer to store whether the primal ray is a feasible unboundedness proof, or NULL */
   );
 
/** returns primal ray proving the unboundedness of the current LP */
SCIP_RETCODE SCIPlpExactGetPrimalRay(
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_RATIONAL**       ray                 /**< array for storing primal ray values, they are stored w.r.t. the problem index of the variables,
                                              *   so the size of this array should be at least number of active variables
                                              *   (all entries have to be initialized to 0 before) */
   );
 
/** stores the dual Farkas multipliers for infeasibility proof in rows. besides
 *
 *  @note The Farkas proof is checked for validity if lp/checkfarkas = TRUE and @p valid is not NULL.
 */
SCIP_RETCODE SCIPlpExactGetDualfarkas(
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_STAT*            stat,               /**< problem statistics */
   SCIP_Bool*            valid,              /**< pointer to store whether the Farkas proof is valid  or NULL */
   SCIP_Bool             overwritefplp       /**< should the floating point values be overwritten, e.g. if fp lp was infeasible */
   );
 
/** get number of iterations used in last LP solve */
SCIP_RETCODE SCIPlpExactGetIterations(
   SCIP_LPEXACT*         lpexact,            /**< current exact LP data */
   int*                  iterations          /**< pointer to store the iteration count */
   );
 
/** gets objective value of current LP
 *
 *  @note This method returns the objective value of the current LP solution, which might be primal or dual infeasible
 *        if a limit was hit during solving. It must not be used as a dual bound if the LP solution status is
 *        SCIP_LPSOLSTAT_ITERLIMIT or SCIP_LPSOLSTAT_TIMELIMIT.
 */
void SCIPlpExactGetObjval(
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_RATIONAL*        res                 /**< result pointer to store rational */
   );
 
/** gets the pseudo objective value for the current search node; that is all variables set to their best (w.r.t. the
 *  objective function) local bound
 */
void SCIPlpExactGetPseudoObjval(
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_RATIONAL*        res                 /**< result pointer to store rational */
   );
 
/** removes all columns after the given number of cols from the LP */
SCIP_RETCODE SCIPlpExactShrinkCols(
   SCIP_LPEXACT*         lpexact,            /**< LP data */
   SCIP_SET*             set,                /**< global SCIP settings */
   int                   newncols            /**< new number of columns in the LP */
   );
 
/** removes and releases all rows after the given number of rows from the LP */
SCIP_RETCODE SCIPlpExactShrinkRows(
   SCIP_LPEXACT*         lpexact,            /**< LP data */
   BMS_BLKMEM*           blkmem,             /**< block memory */
   SCIP_SET*             set,                /**< global SCIP settings */
   int                   newnrows            /**< new number of rows in the LP */
   );
 
/* deletes the marked rows from the LP and the LP interface */
SCIP_RETCODE SCIPlpExactDelRowset(
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   BMS_BLKMEM*           blkmem,             /**< block memory buffers */
   SCIP_SET*             set,                /**< global SCIP settings */
   int*                  rowdstat            /**< deletion status of rows:  1 if row should be deleted, 0 if not */
   );
 
/** resets the LP to the empty LP by removing all columns and rows from LP, releasing all rows, and flushing the
 *  changes to the LP solver
 */
SCIP_RETCODE SCIPlpExactReset(
   SCIP_LPEXACT*         lpexact,            /**< LP data */
   BMS_BLKMEM*           blkmem,             /**< block memory */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_STAT*            stat,               /**< problem statistics */
   SCIP_EVENTQUEUE*      eventqueue          /**< event queue */
   );
 
/** removes all columns and rows from LP, releases all rows */
SCIP_RETCODE SCIPlpExactClear(
   SCIP_LPEXACT*         lpexact,            /**< LP data */
   BMS_BLKMEM*           blkmem,             /**< block memory */
   SCIP_SET*             set                 /**< global SCIP settings */
   );
 
/** forces an exact lp to be solved in the next exact bound computation */
void SCIPlpExactForceExactSolve(
   SCIP_LPEXACT*         lpexact,            /**< exact LP data */
   SCIP_SET*             set                 /**< global SCIP settings */
   );
 
/** forces the next exact bound computation to be executed even in probing mode */
void SCIPlpExactForceSafeBound(
   SCIP_LPEXACT*         lpexact,            /**< exact LP data */
   SCIP_SET*             set                 /**< global SCIP settings */
   );
 
/** allows an exact lp to be solved in the next exact bound computation */
void SCIPlpExactAllowExactSolve(
   SCIP_LPEXACT*         lpexact,            /**< exact LP data */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_Bool             allowexact          /**< TRUE if next safe bounding call should be allowed to be exact, FALSE otherwise */
   );
 
/** gets solution status of current exact LP */
SCIP_LPSOLSTAT SCIPlpExactGetSolstat(
   SCIP_LPEXACT*         lpexact             /**< current LP data */
   );
 
/** sets the upper objective limit of the exact LP solver */
SCIP_RETCODE SCIPlpExactSetCutoffbound(
   SCIP_LPEXACT*         lpexact,            /**< current exact LP data */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_Real             cutoffbound         /**< new upper objective limit */
   );
 
/** solves the LP with simplex algorithm, and copy the solution into the column's data */
SCIP_RETCODE SCIPlpExactSolveAndEval(
   SCIP_LPEXACT*         lpexact,            /**< LP data */
   SCIP_LP*              lp,                 /**< LP data */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_MESSAGEHDLR*     messagehdlr,        /**< message handler */
   BMS_BLKMEM*           blkmem,             /**< block memory buffers */
   SCIP_STAT*            stat,               /**< problem statistics */
   SCIP_EVENTQUEUE*      eventqueue,         /**< event queue */
   SCIP_PROB*            prob,               /**< problem data */
   SCIP_Longint          itlim,              /**< maximal number of LP iterations to perform, or -1 for no limit */
   SCIP_Bool*            lperror,            /**< pointer to store whether an unresolved LP error occurred */
   SCIP_Bool             usefarkas           /**< are we aiming to prove infeasibility? */
   );
 
/** stores exact LP state (like basis information) into LP state object */
SCIP_RETCODE SCIPlpExactGetState(
   SCIP_LPEXACT*         lpexact,            /**< exact LP data */
   BMS_BLKMEM*           blkmem,             /**< block memory */
   SCIP_LPISTATE**       lpistate            /**< pointer to LP state information (like basis information) */
   );
 
/** loads exact LP state (like basis information) into solver */
SCIP_RETCODE SCIPlpExactSetState(
   SCIP_LPEXACT*         lpexact,            /**< exact LP data */
   BMS_BLKMEM*           blkmem,             /**< block memory */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_EVENTQUEUE*      eventqueue,         /**< event queue */
   SCIP_LPISTATE*        lpistate,           /**< LP state information (like basis information) */
   SCIP_Bool             wasprimfeas,        /**< primal feasibility when LP state information was stored */
   SCIP_Bool             wasprimchecked,     /**< true if the LP solution has passed the primal feasibility check */
   SCIP_Bool             wasdualfeas,        /**< dual feasibility when LP state information was stored */
   SCIP_Bool             wasdualchecked      /**< true if the LP solution has passed the dual feasibility check */
   );
 
/** frees exact LP state information */
SCIP_RETCODE SCIPlpExactFreeState(
   SCIP_LPEXACT*         lpexact,            /**< exact LP data */
   BMS_BLKMEM*           blkmem,             /**< block memory */
   SCIP_LPISTATE**       lpistate            /**< pointer to LP state information (like basis information) */
   );
 
/** starts exact LP diving and saves bounds and objective values of columns to the current nodes's values */
SCIP_RETCODE SCIPlpExactStartDive(
   SCIP_LPEXACT*         lpexact,            /**< current exact LP data */
   BMS_BLKMEM*           blkmem,             /**< block memory */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_STAT*            stat                /**< problem statistics */
   );
 
/** quits exact LP diving and resets bounds and objective values of columns to the current node's values */
SCIP_RETCODE SCIPlpExactEndDive(
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   BMS_BLKMEM*           blkmem,             /**< block memory */
   SCIP_SET*             set,                /**< global SCIP settings */
   SCIP_STAT*            stat,               /**< problem statistics */
   SCIP_EVENTQUEUE*      eventqueue,         /**< event queue */
   SCIP_VAR**            vars,               /**< array with all active variables */
   int                   nvars               /**< number of active variables */
   );
 
/** writes exact LP to a file */
SCIP_RETCODE SCIPlpExactWrite(
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   const char*           fname               /**< file name */
   );
 
/** overwrites the dual values stored in the fp lp with exact values */
void SCIPlpExactOverwriteFpDualSol(
   SCIP_LPEXACT*         lpexact,            /**< current LP data */
   SCIP_Bool             dualfarkas          /**< TRUE if farkas proof, FALSE if dual sol? */
   );
 
/** synchronizes the exact LP with cuts from the floating-point LP */
SCIP_RETCODE SCIPlpExactSyncLPs(
   SCIP_LPEXACT*         lpexact,            /**< LP data */
   BMS_BLKMEM*           blkmem,             /**< block memory */
   SCIP_SET*             set                 /**< global SCIP settings */
   );
 
#ifdef __cplusplus
}
#endif
 
#endif