org.sosy_lab.solver.reusableStack

Class ReusableStackInterpolatingProver<T>

java.lang.Object

org.sosy_lab.solver.reusableStack.ReusableStackInterpolatingProver<T>

All Implemented Interfaces:

AutoCloseable, BasicProverEnvironment<T>, InterpolatingProverEnvironment<T>

public class ReusableStackInterpolatingProver<T>
extends Object
implements InterpolatingProverEnvironment<T>

Constructor Summary

Constructors

Constructor and Description
ReusableStackInterpolatingProver(InterpolatingProverEnvironment<T> pDelegate)

Method Summary

Modifier and Type	Method and Description
T	addConstraint(BooleanFormula pConstraint) Add constraint to the context.
void	close() Closes the prover environment.
BooleanFormula	getInterpolant(List<T> pFormulasOfA) Get an interpolant for two groups of formulas.
Model	getModel() Get a satisfying assignment.
ImmutableList<Model.ValueAssignment>	getModelAssignments() Get a list of satisfying assignments.
List<BooleanFormula>	getSeqInterpolants(List<Set<T>> pPartitionedFormulas) This method returns interpolants of an 'inductive sequence'.
List<BooleanFormula>	getTreeInterpolants(List<Set<T>> pPartitionedFormulas, int[] pStartOfSubTree) Compute a sequence of interpolants.
boolean	isUnsat() Check whether the conjunction of all formulas on the stack is unsatisfiable.
void	pop() Remove one formula from the environment stack.
void	push() Create backtracking point.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.sosy_lab.solver.api.InterpolatingProverEnvironment

push

Methods inherited from interface org.sosy_lab.solver.api.BasicProverEnvironment

close, getModel, getModelAssignments, isUnsat, pop, push

Constructor Detail

ReusableStackInterpolatingProver

public ReusableStackInterpolatingProver(InterpolatingProverEnvironment<T> pDelegate)

Method Detail

addConstraint

public T addConstraint(BooleanFormula pConstraint)

Description copied from interface: BasicProverEnvironment

Add constraint to the context.

Specified by:

addConstraint in interface BasicProverEnvironment<T>

getInterpolant

public BooleanFormula getInterpolant(List<T> pFormulasOfA)
                              throws SolverException,
                                     InterruptedException

Description copied from interface: InterpolatingProverEnvironment

Get an interpolant for two groups of formulas. This should be called only immediately after an BasicProverEnvironment.isUnsat() call that returned true.

There is no direct guarantee that the interpolants returned are part of an inductive sequence', however this seems to work for most (all?) solvers as long as the same proof is used, i.e. all interpolants are computed after the same SAT-check.

Specified by:

getInterpolant in interface InterpolatingProverEnvironment<T>

Parameters:

pFormulasOfA - A list of values returned by InterpolatingProverEnvironment.push(BooleanFormula). All the corresponding formulas from group A, the remaining formulas form group B.

Returns:

An interpolant for A and B

Throws:

SolverException - if interpolant cannot be computed, for example because interpolation procedure is incomplete

InterruptedException

getSeqInterpolants

public List<BooleanFormula> getSeqInterpolants(List<Set<T>> pPartitionedFormulas)
                                        throws SolverException,
                                               InterruptedException

Description copied from interface: InterpolatingProverEnvironment

This method returns interpolants of an 'inductive sequence'. This property must be supported by the interpolation-strategy of the underlying SMT-solver! Depending on the underlying SMT-solver this method might be faster than N direct calls to getInterpolant().

The stack must contain exactly the partitioned formulas, but any order is allowed. For an input of N partitions we return N-1 interpolants.

Specified by:

getSeqInterpolants in interface InterpolatingProverEnvironment<T>

Returns:

a 'inductive sequence' of interpolants, such that the implication AND(I_i, P_i) => I_(i+1) is satisfied for all i, where P_i is the conjunction of all formulas in partition i.

Throws:

SolverException - if interpolant cannot be computed, for example because interpolation procedure is incomplete

InterruptedException

getTreeInterpolants

public List<BooleanFormula> getTreeInterpolants(List<Set<T>> pPartitionedFormulas,
                                                int[] pStartOfSubTree)
                                         throws SolverException,
                                                InterruptedException

Description copied from interface: InterpolatingProverEnvironment

Compute a sequence of interpolants. The nesting array describes the start of the subtree for tree interpolants. For inductive sequences of interpolants use a nesting array completely filled with 0.

Example:

 A  D
 |  |
 B  E
 | /
 C
 |
 F  H
 | /
 G

 arrayIndex     = [0,1,2,3,4,5,6,7]  // only for demonstration, not needed
 partition      = [A,B,D,E,C,F,H,G]  // post-order of tree
 startOfSubTree = [0,0,2,2,0,0,6,0]  // index of left-most leaf of the current element
 

Specified by:

getTreeInterpolants in interface InterpolatingProverEnvironment<T>

Parameters:

pPartitionedFormulas - of formulas

pStartOfSubTree - The start of the subtree containing the formula at this index as root.

Returns:

Tree interpolants respecting the nesting relation.

Throws:

SolverException - if interpolant cannot be computed, for example because interpolation procedure is incomplete

InterruptedException

isUnsat

public boolean isUnsat()
                throws SolverException,
                       InterruptedException

Description copied from interface: BasicProverEnvironment

Check whether the conjunction of all formulas on the stack is unsatisfiable.

Specified by:

isUnsat in interface BasicProverEnvironment<T>

Throws:

SolverException

InterruptedException

push

public final void push()

Description copied from interface: BasicProverEnvironment

Create backtracking point.

Specified by:

push in interface BasicProverEnvironment<T>

pop

public void pop()

Description copied from interface: BasicProverEnvironment

Remove one formula from the environment stack.

Specified by:

pop in interface BasicProverEnvironment<T>

getModel

public Model getModel()
               throws SolverException

Description copied from interface: BasicProverEnvironment

Get a satisfying assignment. This should be called only immediately after an BasicProverEnvironment.isUnsat() call that returned false.

Specified by:

getModel in interface BasicProverEnvironment<T>

Throws:

SolverException

getModelAssignments

public ImmutableList<Model.ValueAssignment> getModelAssignments()
                                                         throws SolverException

Description copied from interface: BasicProverEnvironment

Get a list of satisfying assignments. This is equivalent to ImmutableList.copyOf(getModel()), but removes the need for calling Model.close().

Note that if you need to iterate multiple times over the model it may be more efficient to use this method instead of BasicProverEnvironment.getModel() (depending on the solver).

Specified by:

getModelAssignments in interface BasicProverEnvironment<T>

Throws:

SolverException

close

public void close()

Description copied from interface: BasicProverEnvironment

Closes the prover environment. The object should be discarded, and should not be used after closing.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface BasicProverEnvironment<T>