private int minChildPos( int pos ) {
	int retVal;
	int lc = 2*pos + 1; //index of left child
	int rc = 2*pos + 2; //index of right child

	//pos is not in the heap or pos is a leaf position
	if ( pos < 0 || pos >= _heap.size() || lc >= _heap.size() )
	    retVal = -1;
	//if no right child, then left child is only option for min
	else if ( rc >= _heap.size() )
	    retVal = lc;
	//have 2 children, so compare to find least
	else if ( _heap.get(lc).getPri() < _heap.get(rc).getPri() )
	    retVal = lc;
	else
	    retVal = rc;
	return retVal;
    }//O(1)