/**
* Check if the literal can be used to explain this clause. It checks it against the unit literal
* that should be explained by a unit clause. If the given literal "lit" has a lower stack
* position than the unit literal for which the unit clause is generated, it may not be used in
* the explanation.
*
* @param lit The literal that we would like to include in the explanation clause.
* @return true if the literal may appear in the clause.
*/
public boolean canExplainWith(Literal lit) {
DPLLAtom atom = lit.getAtom();
return atom.getStackPosition() >= 0
&& (mExplainedLiteral == null
|| mExplainedLiteral.getAtom().getStackPosition() == -1
|| atom.getStackPosition() < mExplainedLiteral.getAtom().getStackPosition());
}
/**
* Get the decide level on which all literals must live if they are allowed to appear in the
* explained clause.
*
* @return the decide level of the explained unit literal or the current decide level if a
* conflict is explained.
*/
public int getDecideLevel() {
return mExplainedLiteral == null
? mSolver.mEngine.getDecideLevel()
: mExplainedLiteral.getAtom().getDecideLevel();
}