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/******************************************************************************
* Top contributors (to current version):
* Yancheng Ou
*
* This file is part of the cvc5 project.
*
* Copyright (c) 2009-2021 by the authors listed in the file AUTHORS
* in the top-level source directory and their institutional affiliations.
* All rights reserved. See the file COPYING in the top-level source
* directory for licensing information.
* ****************************************************************************
*
* The base class for optimizers of individual cvc5 type.
*/
#ifndef CVC5__OMT__OMT_OPTIMIZER_H
#define CVC5__OMT__OMT_OPTIMIZER_H
#include "smt/optimization_solver.h"
namespace cvc5::omt {
/**
* The base class for optimizers of individual CVC type
*/
class OMTOptimizer
{
public:
virtual ~OMTOptimizer() = default;
/**
* Returns whether node supports optimization
* Currently supported: BitVectors, Integers (preliminary).
* @param node the target node to check for optimizability
* @return whether node supports optimization
**/
static bool nodeSupportsOptimization(TNode node);
/**
* Given an optimization objective,
* retrieve an optimizer specific for the optimization target
* @param objective the an OptimizationObjective object containing
* the optimization target, whether it's maximized or minimized
* and whether it's signed for BV (only applies when the target type is BV)
* @return a unique_pointer pointing to a derived class of OMTOptimizer
* and this is the optimizer for targetNode
**/
static std::unique_ptr<OMTOptimizer> getOptimizerForObjective(
smt::OptimizationObjective& objective);
/**
* Given the lhs and rhs expressions, with an optimization objective,
* makes an incremental expression stating that
* lhs `better than` rhs
* under the context specified by objective
* for minimize, it would be lhs < rhs
* for maximize, it would be lhs > rhs
*
* Note: the types of lhs and rhs nodes must match or be convertable
* to the type of the optimization target!
*
* @param nm the NodeManager to manage the made expression
* @param lhs the left hand side of the expression
* @param rhs the right hand side of the expression
* @param objective the optimization objective
* stating whether it's maximize / minimize etc.
* @return an expression stating lhs `better than` rhs,
**/
static Node mkStrongIncrementalExpression(
NodeManager* nm,
TNode lhs,
TNode rhs,
smt::OptimizationObjective& objective);
/**
* Given the lhs and rhs expressions, with an optimization objective,
* makes an incremental expression stating that
* lhs `better than or equal to` rhs
* under the context specified by objective
* for minimize, it would be lhs <= rhs
* for maximize, it would be lhs >= rhs
*
* Note: the types of lhs and rhs nodes must match or be convertable
* to the type of the optimization target!
*
* @param nm the NodeManager to manage the made expression
* @param lhs the left hand side of the expression
* @param rhs the right hand side of the expression
* @param objective the optimization objective
* stating whether it's maximize / minimize etc.
* @return an expression stating lhs `better than or equal to` rhs,
**/
static Node mkWeakIncrementalExpression(
NodeManager* nm,
TNode lhs,
TNode rhs,
smt::OptimizationObjective& objective);
/**
* Minimize the target node with constraints encoded in optChecker
*
* @param optChecker an SMT solver encoding the assertions as the
* constraints
* @param target the target expression to optimize
* @return smt::OptimizationResult the result of optimization, containing
* whether it's optimal and the optimized value.
**/
virtual smt::OptimizationResult minimize(SmtEngine* optChecker,
TNode target) = 0;
/**
* Maximize the target node with constraints encoded in optChecker
*
* @param optChecker an SMT solver encoding the assertions as the
* constraints
* @param target the target expression to optimize
* @return smt::OptimizationResult the result of optimization, containing
* whether it's optimal and the optimized value.
**/
virtual smt::OptimizationResult maximize(SmtEngine* optChecker,
TNode target) = 0;
};
} // namespace cvc5::omt
#endif /* CVC5__OMT__OMT_OPTIMIZER_H */
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