public void init() {
int nlength = lits.nVars() + 1;
activity = new double[nlength];
phaseStrategy.init(nlength);
activity[0] = -1;
heap = new Heap(activity);
heap.setBounds(nlength);
for (int i = 1; i < nlength; i++) {
assert i > 0;
assert i <= lits.nVars() : "" + lits.nVars() + "/" + i; //$NON-NLS-1$ //$NON-NLS-2$
activity[i] = 0.0;