org.sosy_lab.solver.api

Interface InterpolatingProverEnvironment<T>

Type Parameters:

T - The type of the objects which can be used to select formulas for interpolant creation.

All Superinterfaces:

AutoCloseable, BasicProverEnvironment<T>

All Known Implementing Classes:

InterpolatingProverWithAssumptionsWrapper, ReusableStackInterpolatingProver

public interface InterpolatingProverEnvironment<T>
extends BasicProverEnvironment<T>

This class provides an interface to an incremental SMT solver with methods for pushing and popping formulas as well as SAT checks. Furthermore, interpolants can be generated for an unsatisfiable list of formulas.

See Also:

The non-interpolating ProverEnvironment for general notes that also apply to this interface.

Method Summary

Modifier and Type	Method and Description
BooleanFormula	getInterpolant(List<T> formulasOfA) Get an interpolant for two groups of formulas.
List<BooleanFormula>	getSeqInterpolants(List<Set<T>> partitionedFormulas) This method returns interpolants of an 'inductive sequence'.
List<BooleanFormula>	getTreeInterpolants(List<Set<T>> partitionedFormulas, int[] startOfSubTree) Compute a sequence of interpolants.
boolean	isUnsatWithAssumptions(Collection<BooleanFormula> assumptions) Check whether the conjunction of all formulas on the stack is unsatisfiable with regards to provided assumptions.
default T	push(BooleanFormula f) Add a formula to the environment stack, asserting it.

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

addConstraint, close, getModel, getModelAssignments, isUnsat, pop, push

Method Detail

push

default T push(BooleanFormula f)

Add a formula to the environment stack, asserting it. The returned value can be used when selecting the formulas for interpolant generation.

Specified by:

push in interface BasicProverEnvironment<T>

getInterpolant

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

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.

Parameters:

formulasOfA - A list of values returned by 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

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

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.

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

List<BooleanFormula> getTreeInterpolants(List<Set<T>> partitionedFormulas,
                                         int[] startOfSubTree)
                                  throws SolverException,
                                         InterruptedException

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
 

Parameters:

partitionedFormulas - of formulas

startOfSubTree - 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

isUnsatWithAssumptions

boolean isUnsatWithAssumptions(Collection<BooleanFormula> assumptions)
                        throws SolverException,
                               InterruptedException

Check whether the conjunction of all formulas on the stack is unsatisfiable with regards to provided assumptions. The implementation of this method must be consistent with AbstractSolverContext.supportsAssumptionSolving().

Throws:

SolverException

InterruptedException