ILOG CPLEX .NET Reference Manual

Cplex.HeuristicCallback.IsDualFeasible Method 

Returns true if a dual feasible solution is available for the current node.

public virtual bool IsDualFeasible();

Remarks

If false is returned the solution may still be dual feasible, but the algorithm has not determined the feasibility before it terminated.

See Also

Cplex.HeuristicCallback Class | ILOG.CPLEX Namespace