Class SolveResult

Namespace

OptalCP

Assembly

OptalCP.dll

Holds the solution, objective, statistics, and solve status after solving.

public class SolveResult

Inheritance

object

SolveResult

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

Remarks

The result returned by Model.Solve or Solver.Solve.

Contains comprehensive information about the solve:

Solution data:

• SolveResult.Solution: The best solution found (or None if no solution exists)
• SolveResult.Objective: The objective value of the best solution
• SolveResult.ObjectiveBound: The proved bound on the objective

Solve statistics:

• SolveResult.NbSolutions: Total number of solutions found
• SolveResult.Proof: Whether optimality or infeasibility was proved
• SolveResult.Duration: Total solve time in seconds

History tracking:

• SolveResult.ObjectiveHistory: When each improving solution was found
• SolveResult.ObjectiveBoundHistory: When each bound improvement was proved

Example:

var model = new Model();
// ... build model ...
var result = model.Solve();
if (result.solution != null) {
Console.WriteLine($"Found solution with objective {result.objective}");
Console.WriteLine($"Best solution found at {result.solutionTime:F2}s");
if (result.proof)
Console.WriteLine("Solution is optimal!");
} else {
if (result.proof)
Console.WriteLine("Problem is infeasible");
else
Console.WriteLine("No solution found within time limit");
}

Properties

ActualWorkers

Number of worker threads actually used during solving.

public int ActualWorkers { get; }

Property Value

int

Worker count.

Remarks

This is the actual number of workers used by the solver, which may differ from the requested Parameters.nbWorkers if that parameter was not specified (auto-detect) or if the system has fewer cores than requested.

BoundTime

Time of the last objective bound improvement.

public double? BoundTime { get; }

Property Value

double?

The time in seconds, or None if no bound was proved.

Remarks

The time is measured from the start of the solve, in seconds.

Returns None when no bound was proved during the solve.

Cpu

CPU name detected by the solver.

public string Cpu { get; }

Property Value

string

CPU model name.

Remarks

Contains the CPU model name as detected by the operating system.

Duration

Total duration of the solve in seconds.

public double Duration { get; }

Property Value

double

Seconds elapsed.

MemoryUsed

Memory used by the solver in bytes.

public long MemoryUsed { get; }

Property Value

long

Bytes used.

NbBranches

Total number of branches explored during the solve.

public long NbBranches { get; }

Property Value

long

Branch count.

NbConstraints

Number of constraints in the model.

public int NbConstraints { get; }

Property Value

int

Constraint count.

NbFails

Total number of failures encountered during the solve.

public long NbFails { get; }

Property Value

long

Failure count.

NbIntVars

Number of integer variables in the model.

public int NbIntVars { get; }

Property Value

int

Integer variable count.

NbIntervalVars

Number of interval variables in the model.

public int NbIntervalVars { get; }

Property Value

int

Interval variable count.

NbLNSSteps

Total number of Large Neighborhood Search steps.

public long NbLNSSteps { get; }

Property Value

long

LNS step count.

NbRestarts

Total number of restarts performed during the solve.

public long NbRestarts { get; }

Property Value

long

Restart count.

NbSolutions

Number of solutions found during the solve.

public int NbSolutions { get; }

Property Value

int

Solution count.

Objective

Best objective value found (for optimization problems).

public long? Objective { get; }

Property Value

long?

The objective value, or None if not applicable.

Remarks

The value is None when:

• No objective was specified in the model (no Model.Minimize or Model.Maximize call).
• No solution was found.
• The objective expression has an absent value in the best solution.

ObjectiveBound

Proved bound on the objective value.

public long? ObjectiveBound { get; }

Property Value

long?

The objective bound, or None if no bound was proved.

Remarks

For minimization problems, this is a lower bound: the solver proved that no solution exists with an objective value less than this bound.

For maximization problems, this is an upper bound: the solver proved that no solution exists with an objective value greater than this bound.

The value is None when no bound was proved or for satisfaction problems.

ObjectiveBoundHistory

History of objective bound improvements during the solve.

public IReadOnlyList<ObjectiveBoundEntry> ObjectiveBoundHistory { get; }

Property Value

IReadOnlyList<ObjectiveBoundEntry>

Sequence of bound entries, one per bound improvement.

Remarks

Returns a sequence of ObjectiveBoundEntry objects, one for each bound improvement proved during the solve.

Each entry contains:

• ObjectiveBoundEntry.SolveTime: When the bound was proved
• ObjectiveBoundEntry.Value: The bound value

For minimization problems, these are lower bounds. For maximization problems, these are upper bounds. The entries are ordered chronologically by solve time.

ObjectiveHistory

History of objective value improvements during the solve.

public IReadOnlyList<ObjectiveEntry> ObjectiveHistory { get; }

Property Value

IReadOnlyList<ObjectiveEntry>

Sequence of objective entries, one per solution found.

Remarks

Returns a sequence of ObjectiveEntry objects, one for each solution found during the solve.

Each entry contains:

• ObjectiveEntry.SolveTime: When the solution was found
• ObjectiveEntry.Objective: The objective value of that solution
• ObjectiveEntry.Valid: Whether the solution was verified

The entries are ordered chronologically by solve time.

ObjectiveSense

Objective direction.

public string? ObjectiveSense { get; }

Property Value

string

'minimize', 'maximize', or None for satisfaction problems.

Remarks

Indicates whether the model was a minimization problem, maximization problem, or a satisfaction problem (no objective).

Proof

Whether the solve ended with a proof (optimality or infeasibility).

public bool Proof { get; }

Property Value

bool

True if the solve completed with a proof.

Remarks

When True, the solver has either:

• Proved optimality (found a solution within the bounds defined by Parameters.absoluteGapTolerance and Parameters.relativeGapTolerance), or
• Proved infeasibility (no solution exists)

When False, the solve was interrupted (e.g., by time limit) before a proof could be established.

Solution

The best solution found during the solve.

public Solution? Solution { get; }

Property Value

Solution

The best solution, or None if no solution was found.

Remarks

For optimization problems, this is the solution with the best objective value. For satisfaction problems, this is the last solution found.

Returns None when no solution was found (the problem may be infeasible or the solve was interrupted before finding any solution).

SolutionTime

Time when the best solution was found.

public double? SolutionTime { get; }

Property Value

double?

The time in seconds, or None if no solution was found.

Remarks

The time is measured from the start of the solve, in seconds.

Returns None when no solution was found.

SolutionValid

Whether the best solution was verified.

public bool? SolutionValid { get; }

Property Value

bool?

True if verified, None if verification was not performed.

Remarks

When parameter Parameters.verifySolutions is set to True (the default), the solver verifies all solutions found. The verification checks that all constraints in the model are satisfied and that the objective value is computed correctly.

Possible values:

• None - verification was not performed (parameter was not set)
• True - the solution was verified and correct

The value can never be False because, in that case, the solver would stop with an error.

Solver

Solver name and version string.

public string Solver { get; }

Property Value

string

The solver identification string.

Remarks

Contains the solver name followed by its version number.

Methods

ToString()

Returns a string that represents the current object.

public override string ToString()

Returns

string

A string that represents the current object.