internal void Refine(PRED psi)
{
if (left == null && right == null)
{
#region leaf
var phi_and_psi = solver.MkAnd(phi, psi);
if (solver.IsSatisfiable(phi_and_psi))
{
var phi_min_psi = solver.MkAnd(phi, solver.MkNot(psi));
if (solver.IsSatisfiable(phi_min_psi))
{
left = new PartitonTree <PRED>(solver, nr + 1, this, phi_and_psi, null, null);
right = new PartitonTree <PRED>(solver, nr + 1, this, phi_min_psi, null, null);
}
else // [[phi]] subset of [[psi]]
{
left = new PartitonTree <PRED>(solver, nr + 1, this, phi, null, null); //psi must true
}
}
else // [[phi]] subset of [[not(psi)]]
{
right = new PartitonTree <PRED>(solver, nr + 1, this, phi, null, null); //psi must be false
}
#endregion
}
else if (left == null)
{
right.Refine(psi);
}
else if (right == null)
{
left.Refine(psi);
}
else
{
#region nonleaf
var phi_and_psi = solver.MkAnd(phi, psi);
if (solver.IsSatisfiable(phi_and_psi))
{
var phi_min_psi = solver.MkAnd(phi, solver.MkNot(psi));
if (solver.IsSatisfiable(phi_min_psi))
{
left.Refine(psi);
right.Refine(psi);
}
else // [[phi]] subset of [[psi]]
{
left.ExtendLeft(); //psi is true
right.ExtendLeft();
}
}
else // [[phi]] subset of [[not(psi)]]
{
left.ExtendRight();
right.ExtendRight(); //psi is false
}
#endregion
}
}
