Interface changes between SCIP 3.0 and SCIP 3.1

New and changed callbacks

• Branching Rules:
  
  
  • new possible return value "SCIP_DIDNOTFIND" for SCIP_DECL_BRANCHEXECLP(), SCIP_DECL_BRANCHEXECPS(), and SCIP_DECL_BRANCHEXECEXT() callbacks to state that the branching rule searched, but did not find a branching.

• Domain Propagation:
  
  
  • added parameter "nmarkedconss" to SCIP_DECL_CONSPROP() callback which gives the number of constraints marked for propagation (these constraints are listed first in the conss array given as parameter).

• Message Handler:
  
  
  • New generic messagehandler output callback method SCIP_DECL_MESSAGEOUTPUTFUNC().
  • Removed parameter "msglength" from callback method SCIP_DECL_ERRORPRINTING().

• Variable Pricers:
  
  
  • Added parameter "stopearly" to callback method SCIP_DECL_PRICERREDCOST(). This boolean pointer should be used by the pricer to state whether early branching should be performed, even if new variables were added in the current pricing round.

• Primal Heuristics:
  
  
  • Added parameter "nodeinfeasible" to SCIP_DECL_HEUREXEC() callback which states whether the current subproblem was already detected to be infeasible. In this case, the current LP solution might not respect local bounds, and the heuristic must not assume that it does.

Changed interface methods

• Branching Rules:
  
  
  • Added parameter "nfracimplvars" to SCIPgetLPBranchCands()

• Constraint Handlers:
  
  
  • New method SCIPconshdlrGetStrongBranchPropTime() which returns the time used for domain propagation methods of the constraint handler during strong branching.
  • New method SCIPconsIsMarkedPropagate() which returns whether a constraint is marked for propagation.
  • New methods SCIPconsAddUpgradeLocks() and SCIPconsGetNUpgradeLocks() to increase or get the number of upgrade locks of a constraint.

• Domain Propagation:
  
  
  • New method SCIPpropGetStrongBranchPropTime() which returns the time spent by a domain propagator during strong branching.
  • New methods SCIPmarkConsPropagate() and SCIPunmarkConsPropagate to (un)mark a constraint for propagation.

• LP and Cutting Planes:
  
  
  • New methods SCIProwChgRank() and SCIProwGetRank() to change and get the rank of a cutting plane, respectively.
  • Added parameter "sidetypes" to SCIPcalcMIR() to specify the specify row side type to be used.
  • Added parameter "cutrank" to SCIPcalcMIR() and SCIPcalcStrongCG() which stores the rank of the returned cut.
  • New method SCIPisCutApplicable() which returns whether a cut is good enough to be applied.
  • Added parameter "infeasible" to SCIPaddCut() which is a pointer to store whether the cut is infeasible for the local bounds.
  • delayed cutpool
  • New methods SCIPchgRowLhsDive() and SCIPchgRowRhsDive() to change left and right hand side of a row during diving.
  • Added parameter "cutoff" to SCIPsolveDiveLP(), SCIPsolveProbingLP(), and SCIPsolveProbingLPWithPricing() which is a pointer to store whether the diving/probing LP was infeasible or the objective limit was reached.

• Message Handler:
  
  
  • New method SCIPmessageVPrintError() to print an error message.
  • Removed method SCIPmessagePrintWarningHeader().

• Parameters:
  
  
  • New method SCIPparamGetCharAllowedValues() to get the allowed values for a char parameter.

• Variables:
  
  
  • New structure to store value-based branching and inference history (see pub_history.h).
  • New method SCIPvarGetValuehistory() to get the value-based history of a variable.

• Data structures:
  
  
  • New method SCIPgmlWriteNodeWeight() to write a node section including weight to a .gml graph file.
  • New methods SCIPsparseSolGetFirstSol() and SCIPsparseSolGetNextSol() to get the first sparse solution or iterate over the sparse solutions, respectively.
  • New methods in pub_misc.h to handle a (circular) queue, e.g., SCIPqueueCreate(), SCIPqueueFree(), SCIPqueueInsert(), ...
  • New methods for hash tables: SCIPhashtableRemoveAll(), SCIPhashtableGetNElements(), SCIPhashtableGetLoad()
  • New methods in pub_misc.h to handle a resource activity, e.g., SCIPactivityCreate(), SCIPactivityFree(), SCIPactivityGetVar(), SCIPactivityGetDemand() ...
  • New methods for digraphs: SCIPdigraphResize() to resize the graph and SCIPdigraphSetNodeDatas() and SCIPdigraphGetNodeDatas() to set and get the data attached to the nodes.

• Misc:
  
  
  • New method SCIPcopyOrig() to copy the original problem. Analoguosly, use SCIPcopyOrigProb(), SCIPcopyOrigVars(), and SCIPcopyOrigConss() to copy original problem data, variables, or constraints, respectively.
  • New method SCIPcopyImplicationsCliques() to copy implications and cliques to a copied SCIP instance.
  • New method SCIPgetParam() to get the parameter with a given name.
  • New method SCIPaddOrigObjoffset() to add an offset to the objective function.
  • New method SCIPgetNCheckConss() which returns the number of checked constraints.
  • Added parameter "endptr" to SCIPparseVar() which stores the final string position after parsing.
  • Added parameter "enablepropagation" to SCIPstartStrongbranch(), which can be used to enable strong branching with domain propagation.
  • New method SCIPgetVarStrongbranchWithPropagation() which performs strong branching with propagation on a variable.
  • New method SCIPwriteCliqueGraph() to write the clique graph.
  • New method SCIPdoNotMultaggr() which returns whether multi-aggregation was disabled.
  • Added parameter "lazyconss" to SCIPwriteMIP() to swith writing removable rows as lazy constraints.
  • New method SCIPcreateFiniteSolCopy() to create a copy of a solution with infinite fixings removed.
  • New method SCIPadjustImplicitSolVals() which sets implicit integer variables to an integer value in the given solution without deteriorating its objective value.
  • New method SCIPprintDualSol() which prints the dual solution for a pure LP (works only with preprocessing disabled).
  • New method SCIPgetOpenNodesData() which returns all unprocessed nodes.
  • New method SCIPgetFirstLPTime() and SCIPgetNRootFirstLPIterations() to return time and iterations for the first LP solve and SCIPgetFirstLPDualboundRoot() and SCIPgetFirstLPLowerboundRoot() to return the first root LP dual and lower bound.
  • New method SCIPgetNLimSolsFound() returning the number of feasible primal solution respecting the objective limit.
  • Added parameter "endline" to SCIPprintDisplayLine() to switch printing a newline symbol at the end of the line.

Miscellaneous

• Moved LP solver interfaces to subdirectory src/lpi.

For further information we refer to the Release notes and the Changelog.